The Plant Cell: In Brief

If you’ve ever grown cucumbers (Cucumis sativus) at home, you know that at some point over the summer, those cucumbers will probably produce a bounty of fruit and only your trusted pickle recipe will help manage the massive number of cucumbers. Rather than being overwhelmed commercial growers want…

F1 plants resulting from crosses between parents of different strains often exhibit improved fitness, known as heterosis, or also hybrid vigor. Hybrids are heavily used in modern agriculture and could be part of the solution to address the challenge of feeding an ever-growing world population. However,…

Development involves a delicate patterning of cell division and differentiation in three dimensions. This is beautifully illustrated in leaves, where three axes are visible: proximo-distal (from base to tip), medio-lateral (from the midvein to the margin/edge of the blade) and adaxial-abaxial (from upper…

Cereal grains accumulate large amounts of proteins and starch and are a major source of dietary calories for humans and animals. In maize (Zea mays), most of the storage compounds are synthesized during the grain-filling period of kernel development. Several key transcription factors (TFs) that regulate…

It's not just human relationships that may require a chaperone to prevent inappropriate interactions. Numerous proteins in organisms from Escherichia coli to us, especially hydrophobic membrane proteins, also require chaperones in aqueous environments to prevent inappropriate interactions such as aggregation…

In plants, small interfering RNAs (siRNAs) serve as key regulators of gene expression. While 24-nucleotide (nt) siRNAs are produced by DCL3 and mediate transcriptional silencing of transposons and pericentromeric chromatin through RdDM (Borges and Martienssen, 2015), 22-nt siRNAs are processed by DCL2…

“Deep learning” is a buzz term that seems to be cropping up in plant biology research these days. Originally reserved, perhaps, for computer nerds rather than us biology ones, deep learning is a type of machine learning used in the field of artificial intelligence. Modeled on the human brain, deep…

The constant evolutionary arms race with pathogens has equipped plants with a layered immune system. As the first line of defense, membrane-localized pattern recognition receptors perceive microbe-associated molecular patterns and activate pattern-triggered immunity (PTI). In parallel, R proteins –…

Moving around taught me two essential skills, only one being relevant here: how to put up wallpaper, and how critical it is to label boxes to help the moving company drop them at their intended location. Now think of a cell: the boxes are vesicles, their contents are proteins and metabolites, and the…

Lignin is a major functional component of plant secondary cell walls and the second most abundant biological polymer on Earth after cellulose. Understanding the biosynthesis of lignin has huge practical implications because lignin is a major by-product of processes that use cellulosic biomass for industrial…

Sweet ripe strawberries (Fragaria spp.) come in colors ranging from deep burgundy to white and everything in between. Such variation attracts consumers and gardeners alike, making fruit color an important breeding target. Strawberry fruit receptacles vary in color due to different levels of anthocyanins.…

Plant floral organ development is orchestrated by master regulatory genes that control the differentiation of meristem tissue. According to the ABC(DE) model of flower development (Bowman et al., 1989; nicely summarized by Irish, 2017), different floral organs form in concentric whorls (verticils) in…

High levels of soil salinity lead to toxic accumulation of sodium (Na+) and chloride (Cl-) ions in plants, which adversely affect plant growth and yield. Plants use several strategies to cope with salt stress. These include removal and compartmentalization of toxic ions, and maintenance of growth and…

Fatty acid (FA) desaturases have long been recognized as key enzymes in synthesizing lipids containing unsaturated FAs, which constitute the majority of seed oil. As a major class of FA desaturases, stearoyl-acyl carrier protein desaturases (SADs) catalyze the first desaturation step, producing the monounsaturated…

The plasma membrane (PM) is an exquisitely dynamic structure. It has to be, since it serves as the interface between the cell and the ever-changing environment. PM-associated signaling proteins shuttle quickly between the PM and the cell’s interior to help the organism respond to whatever comes its…

The plant cell wall is vital for plant survival—it mediates defence against pathogens, provides structural stability and controls growth to produce final plant form. Plant cell walls are composite structures formed mainly from cellulose, hemicelluloses, and pectins, and the interactions of these components…

Protein analysis relies heavily on the production of ‘tagged’ proteins, i.e. recombinant proteins that contain both a functional peptide sequence and a peptide or chemical label (the ‘tag’). Common tags include fluorescent proteins (FPs), which make tagged proteins easier to detect, as well as…

The movement of electrons between molecules and organelles via redox reactions is a cornerstone of cellular metabolism. Electron carriers such as nicotinamide adenine dinucleotide (NAD) and its phosphorylated form NADP mediate reduction or oxidation reactions via their own conversion between reduced…

Circadian clocks act as universal timekeepers to harmonize internal processes with external day-night rhythms. Genetic feedback loops gear these inner clocks by approximating time in response to dawn-dusk cycles. In plants, development, growth, hormone action, metabolism and other downstream events are…

Plant viruses are a major threat to global food security. The large family of geminiviruses has a broad pathogenic impact on economically important crops such as maize, tomato, and cassava and causes millions of tons of losses per year worldwide (Rojas et al., 2005). Geminiviruses possess a circular…

Arabidopsis (Arabidopsis thaliana) chloroplast-division mutants that have abnormally large chloroplasts have been around for quite some time, not only because they can be identified relatively easily through screening (Pyke & Leech 1991) and because their spectacular morphology sparks intrigue, but…

Tissues are composed of specialized cell types. As a cell matures, it acquires the characteristics associated with a specific identity, or fate. This process is called cell differentiation and is crucial for proper organ development. However, after a differentiation program is initiated, the mechanisms…

Arabinogalactan proteins (AGPs) are a family of extracellular proteoglycans that existed in land plants and algae (Johnson et al., 2017). AGPs are part of the hydroxyproline-rich glycoprotein (HRGP) superfamily that also includes extensins and proline-rich proteins. Based on the protein sequence, a glycosylphosphatidylinositol…

Seedling growth and development rely on the successful integration of information from external signals, such as light and temperature, and endogenous processes, such as the rhythmic ticking of the circadian clock. Together, these signaling pathways tune hypocotyl elongation to allow seedlings to escape…

Gamete formation in sexually reproducing plants begins with formation of a “mother cell” that undergoes meiosis to generate haploid spores. Haploid spores further develop into gametophytes within which gametes differentiate. In flowering plants (angiosperms), including crop systems, the female mother…

When we cut out cookies from rolled-out dough, we often end up with unwanted dough scraps, and sometimes the dough sticks to the cookie-cutter, resulting in misshapen cookies. Just like these misshapen cookies, faulty or aberrant RNAs can arise in cells due to mistakes during transcription, RNA processing,…

From the flat white sheets of our favourite weed Arabidopsis thaliana to the colourful cups and spirals of orchids, petals come in a spectacular array of shapes, sizes, colours and textures. These elaborate forms have often evolved to attract pollinators. For example, bee orchids produce petals that…

Plant RNA-dependent RNA polymerases (RDRs) are essential for the biogenesis of small, interfering RNAs (siRNAs). These polymerases function by converting single-stranded RNA transcripts into double-stranded RNAs, which are processed by Dicer-like ribonucleases into 21- to 24-nucleotide siRNAs (reviewed…

Being a multicellular organism is not an easy task. Proper functioning of individual cell types with different functions requires coordination of gene expression to determine cell identity, but also regulatory mechanisms to respond to environmental cues. The root may appear simple at first sight, but…

Plant seeds store nutrients in the form of protein, starch, and oil to support seed germination and seedling establishment. The seed nutrient reserves are supplied with carbon and nitrogen assimilated in vegetative tissues, where primary metabolism oscillates in a circadian manner (Farré and Weise,…

Rubisco catalyzes the key carboxylation step in photosynthetic CO2 fixation and is probably the most abundant protein on Earth. The enzyme is famous for inefficient catalysis and the habit of binding oxygen instead of CO2 in one out of every four binding events, leading to photorespiration reactions…

Plant defenses against herbivore or pathogen attack involve the coordination of multiple hormone-mediated signalling networks, including the jasmonate (JA) and brassinosteroid (BR) pathways. Jasmonate is an oxylipin phytohormone that triggers the transcription of defence-related proteins and secondary…

Most macro-molecular components of plant cells (e.g., proteins, lipids, and even entire organelles) are subject to an ongoing process of recycling to both rejuvenate aging structures and optimize the allocation of cellular nutrients. A major recycling route is autophagy, which occurs under normal conditions…

Transposable Elements (TEs) are mobile genetic elements and major constituents of eukaryotic chromosomes. TEs promote genetic and epigenetic variation within genomes and are a major source of evolutionary novelty and adaptation (Lisch, 2013). In plants, TEs represent from 20% of the genomic content in…

The endoplasmic reticulum (ER) is an organelle that is vital for many cellular processes such as protein and lipid synthesis, calcium signaling, detoxification, and movement of other organelles. It forms an intricate meshwork in the cell cortex that is comprised of highly dynamic interconnected tubules…

Nitrogen (N) is the most abundant element in Earth’s atmosphere. However, plants must capture this essential element from soil through their roots. To do this, legume roots forge symbioses with rhizobia to initiate nodule development. Root nodules provide rhizobia an environment suitable for converting…

When I was a kid, I remember keeping a bottle of wite-out with my pens for the inevitable spelling mistake. Now, in the digital age, I either let my word processor autocorrect spelling errors or wait for the red squiggly line under suspicious words. On any given day, a single (plant) cell by far out-writes…

Storage and remobilization of sugar molecules play important roles for the growth and survival of living organisms. Besides a few exceptions, animals store carbohydrates in the form of soluble glycogen while green plants and algae bank glucans as insoluble starch. Starch forms the basis of human nutrition…

Physical access to regulatory DNA, including cis-regulatory sequences found within proximal promoters and distal enhancer elements, is a vital property of chromatin.  In turn, their access is determined by nucleosome occupancy and post-translational modification of histone proteins. A continuum of chromatin…

ADP-RIBOSYLATION FACTOR (ARF) proteins play essential roles in vesicle trafficking by regulating the formation of membrane vesicles that move cargo throughout the cell. Their activity is controlled by specific guanine exchange factors (ARF-GEFs) that activate ARFs by catalyzing a GDP to GTP exchange…

Cellulose, hemicellulose, and pectin are the brick and mortar of the plant kingdom, and how they are laid has substantial impacts on plant morphology.  Plant cell shape is dictated by the interplay between turgor pressure and heterogeneity in cell wall composition, whereby localized cell wall loosening…

Bacteria use stomatal pores as a point of entry to invade plant leaves. As a first line of defense, plants attempt to counteract this attack by restricting bacterial entry simply by closing the stomata. This happens via reduction in turgor pressure of the two guard cells flanking the stomatal pore, the…

The plant immune system is largely centered around immune receptors that monitor for pathogen-derived signatures. Extracellular immunity is afforded through cell-surface receptors recognizing common microbial motifs like bacterial flagellin or fungal chitin (Boutrot and Zipfel, 2017). By contrast, intracellular…

A single genome gives rise to different cell types and organs in response to precise temporal and spatial regulation of gene expression, driven by developmental and environmental cues. These expression patterns are orchestrated by cis-regulatory elements, distal enhancers and gene-proximal promoters.…

The control of gene expression is of fundamental importance for cellular life. In Eukaryotes, linear DNA is wrapped around nucleosomes that constitute a physical barrier to active transcription. Chromatin remodeling complexes modulate the composition, stability and positioning of nucleosomes therefore…

Membrane vesicle trafficking is the process of moving and distributing signaling molecules from their place of synthesis or capture to target locations inside or outside the cell. Vesicles, mobile membrane compartments produced from the endoplasmic reticulum, carry proteins and other molecules to an…

By now, you would think we’d know everything about cellulose, given its status as the most abundant biopolymer on Earth and its simple chemical composition. Cellulose is composed of β-1,4-D-glucose units assembled into straight chain polymers. These rod-like molecules are packed into strong microfibrils…

During development, seeds pack away large amounts of storage nutrients in the form of starch, proteins, and lipids (typically triacylglycerides), but the ratios of these storage products vary tremendously between seed types. Because of the obvious agricultural implications, researchers have long sought…

Regulation of stomatal opening and closing in plants in response to environmental cues continues to be well studied (García-León et al., 2019; Li et al., 2020), as it is important for balancing the intake of carbon dioxide for photosynthesis (PS) with the release of water during transpiration. But…

MYB proteins are a group of transcription factors that are highly conserved in all vertebrates and were first implicated in avian myeloblastosis (leukemia). Subsequently, they were shown to be cellular proto-oncogenes that regulate production of blood cells in animals. MYB proteins contain a DNA-binding…

Translation of RNA information into protein is a fundamental process ensuring the production of functional proteins in cells. Transfer RNA (tRNA) is a vital component of the translation machinery as it delivers the correct amino acids to the elongating peptide chain based on codon-anticodon recognition.…

The root epidermis presents an elegant model to study cell differentiation. Based on positional cues, Arabidopsis distinguishes two epidermal cell types. Cells in the H position, adjacent to the junction of two cortex cells, have the capacity of developing root hair identity, whereas the non-hair cells…

Plant cell walls provide mechanical support to plant cells, determine their size and shape, and influence plant development and stress responses. The plant cell wall is composed mainly of polysaccharides, including cellulose, hemicellulose and pectins, with smaller amounts of phenolic polymers and proteins…

Decades of research in evolutionary genetics has shown that genomic plasticity, in particular variation in gene copy number, is a favored mechanism to provide rapid adaptation to adverse environmental conditions through increase in gene dosage. Gene amplification has been observed across kingdoms and…

Over 450 million years of land plant evolution has led to the acquisition of diverse and often overlapping sets of defense responses that limit pathogen infection. Decades of research has uncovered canonical immune pathways that provide resistance to specialist (hemi)-biotrophic pathogens relying on…

Nitrogen is an essential component of amino acids, nucleic acids, and even chlorophyll. Plants cannot grow without it. However, acquiring nitrogen is difficult as plants cannot use the most common form, atmospheric nitrogen (N2). To solve this, a select group of flowering plants have evolved to harness…

Seed size is a major component of seed yield. Unveiling the control of seed size provides a theoretical foundation for developing new strategies to boost crop production in the context of global food security. How plants determine their seed size is also a fascinating question in developmental biology.…

Tightly controlled genetic programs regulate developmental phase transitions within distinct tissues and cells. This is especially true for the vegetative-to-reproductive and reproductive-to-seed developmental phase changes that ensure the production of gametes capable of generating viable seed upon…

In a world full of herbivores and mechanical stresses, the ability to sense and respond to wounding is crucial for plants, as injuries open doors for phytopathogen entry and allow uncontrolled evaporation. Wounding triggers local and systemic defenses that heal injuries, make plants taste unpleasant…

Besides making our daily lives sweeter, sugars are the most important energy source in all organisms. Balancing their availability and regulating their partitioning between tissues are major determinants for growth and development. In plants, sucrose is the main product of photosynthesis and is transported…

Gibberellins (GAs) and abscisic acid (ABA) affect plant development in an opposite manner. GA is generally considered a growth promoting hormone, whereas ABA signaling, triggered in response to stress, counteracts the GA effects and restricts growth under suboptimal conditions (Vanstraelen and Benkova,…

Contrary to animals, sex chromosomes in flowering plants (angiosperms) have evolved at least hundreds of times independently, providing an opportunity to unravel the mechanisms underlying their repeated evolution. In the XY system, the Y chromosome dominantly confers male identity: XY individuals…

Linking genotype to phenotype is a major challenge in plant biology. Phenotypic variation observed between individuals of a same plant species is the consequence of a vast array of genetic variation, including Single Nucleotide Polymorphisms (SNPs) and small or large structural variants including Copy…

Shoot architecture is a key ecological and agricultural trait that impacts biomass, the potential to harvest light, planting density, and the reproductive success of a plant. Branching is a prominent feature of plant shoot architecture. A shoot branch develops from an axillary bud, which is located in…

Eukaryotic gene expression is largely governed by transcription factors (TFs), the nuclear proteins that bind to specific DNA sequences and determine when and where genes are turned on. Transcriptional gene regulatory networks (GRNs) that modulate developmental processes and environmental responses consist…

Flowering plants have witnessed multiple cycles of whole-genome duplication (WGD) over the past 200 million years of evolution. Typically, WGD increases genome size and gene content, followed by gene loss, or fractionation, depending on functional categories. Certain classes of genes are retained as…

Plant cell walls are one of the great engineering feats of nature, providing immense structural strength and durability. The core components of plant cell walls (pectin, hemicellulose, and cellulose) can occur in different proportions and vary in their structure and assembly, thus allowing cell walls…

Plants that fail to flower at the right time will lose out on seed production. Hence, the transition from vegetative growth to the reproductive phase depends strongly on environmental signals. Cold winter temperatures and long days are seasonal cues that stimulate flowering through vernalization and…

Many filamentous pathogens invade living plant cells with specialized intracellular infection structures (haustoria) that promote microbial growth. Cytological studies demonstrate that the haustoria of fungal and oomycete pathogens are separated from host cell cytoplasm by a highly differentiated and…

In the legume-rhizobium root nodule, nitrogen fixing rhizobia are accommodated inside plant cells. In the Medicago – Sinorhizobium model system, the internalization of rhizobia into the host plant is triggered by Nod factors secreted from the symbiotic bacteria. The signals are perceived by the host…

In all multicellular organisms, tissue patterning and organogenesis are governed by asymmetric cell divisions (ACDs) and the cellular exchange of positional cues. Plants, unlike animals, undergo post-embryonic organogenesis due to the maintenance of stem cells in specialized niches. One such niche, the…

In eukaryotes, active import of large signaling molecules and proteins over 40kD in the nucleus is mediated by aptly named “importin” proteins. As there are considerably fewer importins than there are cargos, determining how cargo-transporter specificity is mediated constitutes a challenging issue…

Genetic recombination is the process by which novel genotypes are generated from the genetic material of both parents. In eukaryotes, homologous chromosomes synapse and recombine during meiotic prophase I, during which double-stranded breaks (DSBs) are formed by DNA topoisomerases such as SPO11. If large…

Early during seedling development and throughout their lives, plants sense and adapt to their constantly changing environment. Germinated seedlings perceive light which triggers a major developmental switch ultimately leading to photoautotrophic growth. This complex process, referred to broadly as photomorphogenesis,…

Every manufacture relies on a quality control process to ensure that the released product is without defects. Similarly, each transcript leaving the eukaryotic nucleus is subjected to mRNA surveillance, which helps to ensure that only flawless mRNAs are directed to translation. For example, transcripts…

If the planet does not turn to ash before 2050, farmers will need to produce twice as much on roughly the same available arable land to feed the ever-growing world population. But since the Green Revolution of the 1950s and 1960s, progress in crop yield has been incremental. And for good reason: most…

Precise trafficking of proteins to their proper destinations in the cell, whether to an organelle, a membrane, or the cytoplasm, is required for optimal cellular function. Because most plastid proteins are nucleus-encoded and translated in the cytoplasm, proper targeting and import relies on the presence…

In eukaryotes and archaea, protein-coding DNA is transcribed to messenger RNA (mRNA) via a preinitiation complex (PIC) composed of over 100 proteins, among them regulatory proteins, numerous transcription factors, and RNA polymerase II—the enzyme that produces precursor messenger RNA (pre-mRNA). Although…

Successful development of the maize (Zea mays) kernel requires proper nutrient transport and signaling among its genetically distinct components: the embryo that gives rise to the next generation, the endosperm that nourishes the embryo, and the maternal tissues that surround the embryo and the endosperm…

R-loops are three-stranded nucleic acid structures composed of a DNA-RNA hybrid and a displaced single-stranded DNA. R-loops are stable structures as they form an intermediate A/B conformation of the RNA-DNA hybrid that is more stable than the B form of dsDNA or A form of the dsRNA. Recent evidence reveals…

Acyl lipids are a wide range of compounds that have diverse functions in membrane synthesis, energy storage, and signal transduction. Fatty acids are key building blocks of acyl lipids that are synthesized by the fatty acid synthase complex via sequential condensation of two-carbon units to reach lengths…

Stomata, from the Greek “mouths,” are tiny pores in the epidermis of many plant aerial tissues that are “fed” carbon dioxide for making sugar. But plants also lose water through these same pores via transpiration. Stomatal aperture regulation in response to environmental cues is therefore of…

Wheat (Triticum spp.), one of the oldest cultivated cereals, is a major food crop grown in many regions with temperate climates. At present, wheat is grown over a wider area than any other commercial crop. Given its importance, extensive marker-assisted breeding of wheat varieties has been undertaken…

The gibberellin (GA) hormone signaling pathway is a key regulator of major plant developmental processes such as seed germination, cell elongation, and flowering time. The influence of GA is mediated by DELLA repressor proteins which, in the absence of GA, inhibit the activity of transcription factors.…

Plant-viral interactions, like other plant-pathogen interactions, involve a molecular arms race. When plants mount a defense response against an unwanted viral invasion, the invaders eventually evolve mechanisms to thwart or sabotage the defense response, thus placing plants back under pressure to evolve…

Reactive oxygen species (ROS) production is a common early response to biotic or abiotic stresses. While an important messenger in both plants and animals, unrestricted accumulation of ROS has deleterious consequences such as cell death. Thus, the production of ROS is tightly controlled. A main component…

RNA degradation mechanisms control the quality and quantity of mRNAs and are crucial for plant cell viability. The major pathways for RNA degradation involve 5’-3’ or 3’-5’ exonucleolytic cleavage by exoribonucleases or the exosome complex, respectively, whereas targets of miRNAs are cleaved…

During cell division, accurate tethering and release of newly replicated sister chromatids is essential for ensuring that each daughter cell receives a full set of chromosomes. To accomplish this, cells use cohesins that act as the “chromosomal glue”. These cohesins are a group of ring-shaped protein…

At least five RNA polymerases (Pol I to Pol V) are known to exist in plant cells. Pol IV produces short transcripts that are converted into double-stranded RNAs by RNA-dependent RNA polymerase 2 (RDR2) and processed into 24-nucleotide (nt) small interfering RNAs (siRNAs) by DICER-LIKE 3 (DCL3). These…

To survive nutrient scarcity, unicellular organisms establish a reversible quiescent state in which cells cease growth and division and switch metabolism to an energy-conserving mode. When nutrients become available again, cells exit from quiescence and resume growth and division. The mechanistic details…

Land plants (embryophytes) evolved from a freshwater charophycean algal predecessor over 450 million years ago and have since separated into the diversity of plant lineages observed today. A key factor in the expansion of plant life on land was the evolution of rooting structures and a vasculature that…

Root hairs are tubular outgrowths of a subset of root epidermal cells serving multiple roles, including plant anchorage in the soil, water and nutrient absorption, and symbiotic interactions with nitrogen fixing bacteria in legumes (Salazar-Henao et al., 2016). Root hairs form an interface between the…

It has been known for several decades, and suggested as early as the 1930s (Caldwell 1931), that viruses move their proteins and other molecules from one plant cell to the next by altering and regulating plasmodesmata (PD), the tiny doors connecting the cytoplasm between plant cells. And only in the…

For such an important structure, the centromere certainly is hard to pin down, particularly in regard to the relationship between its sequence composition and epigenetic state and its functions in chromosome pairing and kinetochore formation. In addition to undergoing rapid sequence evolution, centromeres…

When seeds germinate underground, the emerging seedlings must push upward through the soil to reach sunlight and begin photoautotrophic growth.  As the hypocotyl emerges from the seed, mechanical pressure against the soil induces production of ethylene, which accumulates and promotes hypocotyl curling.…

Polyubiquitination, the sequential attachment of the small 8kDa globular protein ubiquitin (Ub) to target proteins, represents a major post-translational modification that ultimately determines the substrate’s cellular fate. Ub conjugation is an extremely versatile form of protein regulation since…

‘Senescence’ originates from the Latin word senescere, to grow old. However, the process of leaf senescence is not simply the passive death of the leaf but instead represents an active and highly regulated process of nutrient remobilization from older leaves into developing parts of the plant to…

Numerous proteins coordinate the synthesis, delivery, and assembly of cell wall components during cell wall biosynthesis (McFarlane et al., 2014). KORRIGAN1 (KOR1) is a membrane-anchored endo-β1,4-glucanase glycoprotein involved in the cellulose biosynthesis of primary and secondary cell walls. KOR1…

The fungal pathogen Fusarium virguliforme invades a wide spectrum of host plants, ranging from eudicots to monocots. Interestingly, fungal root colonization results in disease-producing phenotypes only in certain eudicot hosts (Kolander et al., 2012). For instance, F. virguliforme causes sudden death…

Plants have veins too. As in animals, the plant vasculature facilitates the circulation of water and nutrients across tissues and organs. Unlike animals, it originates from a self-renewing population of meristematic cells forming the (pro)cambium ring within stems and tree trunks and roots. Local signals…

In addition to promoting plant growth and development, the colonization of roots by beneficial microorganisms often provides aboveground tissues with enhanced resistance to pathogen attack. This form of resistance, referred to as ‘induced systemic resistance’ (ISR), relies on the long-distance movement…

Iron is a cofactor of numerous plant proteins that function in processes ranging from redox reactions during photosynthesis to respiration. Typical soils contain approximately 1–5% iron, but much of this iron is not readily accessible to plants due to low solubility. Nongraminaceous plants help solubilize…

Plant cell growth is often limited by the availability of two key nutrients, phosphorus (P) and nitrogen (N). As in mammals and yeast, a kinase known as TOR (target of rapamycin) is a key nutrient-responsive regulator of primary metabolism and cell growth in plants (Gonzalez and Hall, 2017; Dobrenel…

Stalk lodging, a structural failure in which crop stalks break prior to harvest, can result in high grain moisture, reduce grain quality, and cause harvesting difficulties. For the popular high-yielding cereal maize (Zea mays), lodging may result in global annual yield reductions of approximately 5-20%…

An enduring goal of biologists is to link variation in the genome to phenotype. The discovery of easily measurable genetic markers in the recent past has led to the identification of variants controlling different traits through linkage analysis. Subsequently, advances in high-throughput sequencing have…

When your fort is under attack during battle, and the wall is breached, you can choose to fight, flee, or forgo. Plants, on the other hand, are left with little choice: they must fight. Winning any battle, though, depends on a multitude of factors, most notably your available arsenal, soldiers, and importantly,…

Floral scent, a blend of volatile organic compounds (VOCs), is a communication signal central to plant interactions. For example, VOCs attract pollinators when flowers are opened (Muhleman et al., 2015). However, some plants do not cross-pollinate and depend less on VOCs. Flowers are fragile structures…

Fixed carbon derived from photosynthates serves critical roles as both a chemical energy reservoir and a building block for anabolic processes.  Environmental constraints that place limitations on a plant’s fixed-carbon economy, such as prolonged darkness and photosynthetic stress, can therefore be…

Chloroplast development in germinating seedlings initiates upon illumination. Whereas chloroplasts in true leaves develop directly from proplastids, chloroplasts in cotyledons of dark-grown seedlings develop from an intermediate type of plastid called an etioplast. During development, etioplasts accumulate…

One of the key aspects of pathogenesis is the ability to sabotage host defenses and, to this end, plant pathogens produce a remarkable set of effector proteins that target host defenses at multiple levels. Plants, in turn, have defenses to counteract these effectors; one key aspect of this is the ability…

Photosystem biogenesis in the chloroplast requires a concerted effort between synthesis and assembly of components including protein subunits, pigments, and other cofactors that varies both temporally and spatially. Sun, Valente-Paterno et al. (2019) investigate the translation zone (T-zone) of unicellular…

MicroRNAs (miRNAs) are a class of small (~21 nucleotide) non-coding RNAs that function as post-transcriptional repressors of gene expression. In plants, miRNAs recognize their target mRNAs based on perfect, or near-perfect, sequence complementarity, ultimately mediating their cleavage and/or translational…

Carotenoid pigments not only produce the vibrant yellows and oranges of flowers, fruits, and autumn leaves, but they also are important in both plant and human health. They act both as accessory pigments in photosynthetic light harvesting and as photoprotectants that absorb excess energy during photosynthesis. …

Following formation of a polyploid plant, cells need to manage issues such as gene dosage and chromosome pairing/segregation to help the formerly separate genomes get along in the same nucleus. As the genomes adjust, chromosomes may undergo recombination, rearrangements, gene loss, and other perturbations,…

An excellent way to explore the function of a gene is to knockout its expression and see what happens. The development of the targeted gene editing system CRISPR (clustered regularly interspaced short palindromic repeats) has triggered scores of gene knockout studies. CRISPR is based on a defense system…

Carotenoids are tetraterpenoid (C40) lipophilic compounds that are widely distributed in nature and play key roles in pigmentation, photosynthesis, and development (Nisar et al., 2015). Detailed biochemical and genetic analyses have uncovered the carotenoid biosynthetic pathway, which generates a diverse…

Saffron spice is prized for its aroma, flavor, and color. The latter derives from highly concentrated apocarotenoid glycosides called crocins.  Accumulation of specialized metabolites like crocins often requires their sequestration in the vacuole to prevent cellular toxicity, feedback inhibition of…

When plants are under attack, they activate defense programs including the biosynthesis of chemical defense compounds. The biosynthesis of these phytochemicals has to occur rapidly and represents a major sink of nutrients and amino acids. How plants optimize the mass production of chemical weapons remains…

Transcription factors (TFs) act through TF binding sites (TFBSs) to control the transcription of associated genes. TFBSs are short and degenerate sequences that are often depicted using a Position Weight Matrix, which contain invariant nucleotides that are crucial for TF binding and variable nucleotides…

Flowering plants integrate endogenous and external cues to accurately time the transition from vegetative to reproductive growth (Cho et al., 2017). Many plants, including Arabidopsis thaliana, sense changes in day length (photoperiod) to transition to flowering as the season changes. Decades of careful…

Arabidopsis thaliana seedlings exposed to heat stress (>42ºC) suffer high lethality rates unless exposed to milder heat (37ºC) beforehand. This pre-exposure distinguishes basal from acquired thermotolerance and has been extensively studied over the years. However, experimental conditions used to…

Identifying natural genetic variation, understanding how it influences traits, and utilizing it for crop improvement is a major objective in plant science. Miller et al. (2019) have identified genetic variation in the promoter region of BnaUPL3.C03 from a panel of Brassica napus accessions that can influence…

Nearly every aspect of growth, morphogenesis, physiology, and stress response is influenced by cell/tissue-type specific gene expression. Transcription factors (TFs) recognize cis-regulatory elements and signal transcription machinery for gene regulation, and the interaction between TFs and their target…

By Jennifer Mach, Science Editor I don’t know how polyploids get their chromosomes paired correctly in meiosis— I can’t even sort my socks. Sometimes I give up and pair random socks, but plants can’t go with random pairings, because that’s a route to death, and with genomes in the dozens…

By Gregory Bertoni Symbiotic associations with microorganisms are widespread among both woody and herbaceous plant species, including most agronomic crops (Brundrett and Tedersoo, 2018). Mycorrhizal fungi provide their hosts with mineral nutrients absorbed from the soil in exchange for fixed carbon…

The lipidic phytohormone jasmonyl-isoleucine (JA-Ile) is a key mediator of stress-versus-growth signaling in vascular plants. Upon it’s accumulation, JA-Ile is detected by the F box receptor protein COI1 (CORONATINE INSENSITIVE1), which in turn leads to the ubiquitination and proteasomal degradation…

The environment plays a major role in determining whether, when, and how growth occurs, and resource allocation towards growth is an important factor in many contexts. For example, plants whose defenses against pathogens are activated often grow less, and plants that must grow taller to reach the light…

Disease resistance (R) receptors detect pathogen effector-mediated host manipulation and induce effector-triggered immunity (ETI) that is often associated with programmed cell death. R proteins are generally conserved across plants, consisting of nucleotide-binding site and leucine rich repeat (NBS-LRR)…

The Golgi apparatus is the central sorting station of the eukaryotic secretory pathway. Protein and lipid cargoes are received at its cis face from the endoplasmic reticulum (ER) and may undergo various modifications including glycosylation before being trafficked onwards from the trans face to their…

Plants have armed themselves with a battalion of photoreceptors to cope with changes in light quantity, quality and direction. Light perception is especially critical when the seedling first emerges from the darkness of the soil and engages the red/far-red light photoreceptors phytochromes (phys). An…

The cell cycle is a tightly coordinated dance with the ultimate goal of dividing one cell into two. Eukaryotic cells tend to divide in the same general pattern, broadly reduced to four phases; cells increase organelle content in the G1 phase, DNA replication occurs in S phase, cells grow in size and…

In Arabidopsis thaliana and related species within the Mustard family (Brassicaceae), the tryptophan (trp)-derived antimicrobial metabolite camalexin (3-thiazol-2-yl-indole) plays a central role in defense against bacterial, fungal, and oomycete pathogens. Upon pathogen attack, cytochrome P450 monooxygenases…

Senescence results from two ineluctable laws of nature: every living entity will eventually die and when it does, nothing will be lost, as everything will be recycled. At the organism level, senescence is an integral part of the plant life cycle, under strict age-dependent genetic control.  This dismantlement…

Modern-day chloroplasts are the descendants of a photosynthetic cyanobacterium that took up residence inside the cytoplasm of a eukaryotic cell. Since this initial cohabitation agreement, the cyanobacterial endosymbiont has dumped most of its genome into the host eukaryotic genome. This creates an engineering…

Techniques to isolate the RNA molecules bound to a specific protein, via co-immunoprecipitation, for instance, have been available for years. The converse—methods to identify the proteins bound to a specific RNA—have been harder to come by, in part because of difficulty in elucidating the determinants…

The discovery of Mediator began with the observation that two transcriptional activators could interfere with each other’s function in vitro, even though they did not bind to the same promoter (Kelleher, Flanagan and Kornberg, 1990). The hypothesis, since then well-validated, was that each transcription…

Adaptive developmental plasticity, in which changing environmental conditions modulate morphogenesis, can help organisms survive harsh conditions. Common examples include the protection of shoot apical meristems by transient arrest and sequestration into bud-like structures in wintering evergreens (e.g.…

Plants have evolved highly sophisticated signalling systems that enable them to coordinate growth and development and respond rapidly to environmental fluctuations. These long-range signals can take the form of mobile small molecules such as phytohormones and RNAs, but can also be electrical signals…

Plants blindly probe the soil for ever-changing pockets of water and nutrients and continuously adjust their root system architecture (RSA) accordingly. Whether they invest more energy in growing existing roots or sending out new lateral roots depends on both genetic programs and environmental factors.…

Genome sequencing has become (relatively) cheap and easy, but assigning functions to the genes identified remains challenging—even in exhaustively studied species such as Arabidopsis thaliana, where functions of ~30% of genes remain unknown. Many of these genes likely have functions that are essential,…

The allotetraploid species white clover (Trifolium repens) resulted from hybridization of two diploid European species whose extant relatives are found only in limited regions–– T. occidentale is a creeping clover found only in saline areas near the shores of Western Europe and T. pallescens is found…

The development of the seed is a complex dance of cell division and differentiation, including transcriptional and genomic repatterning. Measuring gene expression by high-throughput RNA-Seq is routine in laboratories, and numerous seed transcriptomes and microarrays have long been published for maize…

In flowering plants, seed viability is dependent upon the endosperm, a triploid tissue produced by fertilization of a diploid central cell by a haploid sperm. Most endosperm genes are expressed in a 2:1 maternal to paternal ratio reflecting the genomic DNA content. Consequently, balance between maternal…

Plants can adjust their growth and reproduction cycles according to the local climate they experience, but how will they respond when ambient temperatures rise? Most Arabidopsis accessions respond by increasing cell elongation and accelerated flowering, but some cannot cope with higher temperatures and…

Autophagy is the conserved eukaryotic mechanism by which cytoplasmic components such as macromolecular complexes, organelles, and cytosol are degraded in the lysosome or vacuole (Reggiori and Klionsky, 2013). Basal autophagy ensures that obsolete organelles and misfolded proteins are removed from the…

The compounds that give wasabi (Eutrema japonicum) its kick and bok choy (Brassica rapa ssp. chinensis) its distinctive flavor are breakdown products of glucosinolates derived from not so pungent amino acids. These zesty phytochemicals help Brassica plants adapt to their many environmental niches worldwide…

Variegation in different organ types has been of great interest to biologists. The study of pigment variegation in maize kernels led to the discovery of transposable elements (McClintock, 1950), whereas the study of eye pigment variegation in Drosophila has led to interesting insights into chromatin…

The auspicious timing of seasonal germination is crucial to plant fitness and survival. Consequently, seed dormancy is tightly regulated by both developmental and environmental cues, which are integrated via crosstalk between several phytohormone signaling pathways including gibberellins, abscisic acid…

Many of the polysaccharides that make up the plant cell wall carry acetate side groups. Notably, the degree of such acetylation is not always the same—even within the same species, it changes over the course of development and is different between tissues. While the mechanism for adding acetyl groups…

The sub-functionalization and neo-functionalization of duplicated MADS-domain containing transcription factor coding genes has driven angiosperm evolution. These transcription factors control almost every facet of reproductive development in plants and are key breeding targets for crop yield improvement.…

For the past 10 years, a popular method to study global gene expression changes has been RNA sequencing of bulk tissues. However, an inherent limitation of this approach is the confounding of multiple cell types or multiple developmental stages. By contrast, new technologies enable transcriptional profiling…

When thinking about adaptive processes, the concept of genetic innovation comes to mind. At the genomic scale, a lot of attention has been given to gene introgression, duplication, and novel functionalization to uncover the bases of adaptation. However, as the majority of genes are non-essential, both…

All photosynthetic organisms, from cyanobacteria to flowering plants, must continuously adjust to changing light conditions to maximize photosynthetic efficiency while protecting their delicate photochemical centers. During photosynthesis, light energy is preferentially captured by photosystem I (PSI)…

Abiotic stresses constitute a global threat to agricultural crop production and natural ecosystems. One of the most prominent abiotic stresses is drought, which dramatically alters plant physiology and morphology. Studies in model organisms have shed light into how plants respond to drought stress, including…

Plants constantly face the threat of attack from many directions. Organisms like bacteria, viruses, and fungi must be blocked from entering a plant’s cells, or quickly targeted for destruction once inside. Within the plant genome itself, transposable elements lie in wait for reactivation. In addition,…

Plant and animal cells produce various types and sizes of extracellular vesicles (EVs). Mammalian EVs function in intercellular communication and plant EVs carry defense compounds, defense-related proteins, and RNAs and participate in the defense against fungal pathogens (reviewed in Hansen and Nielsen,…

Brassinosteroids (BR) are the only plant hormones with an animal counterpart: steroid hormones. Analysis of BR signaling demonstrated that steroid receptors could reside at the plasma membrane and modulate growth and gene expression, an observation that is now becoming appreciated in non-plant systems…

Small RNAs regulate gene expression and epigenetic modifications (via RNA-directed DNA methylation), and therefore play key roles in plant development (reviewed in Borges and Martienssen, 2015). Moreover, emerging evidence indicates that small RNAs may have a role in the repair of double-stranded breaks…

Fertilizer use in agriculture is one of the essential strategies in improving crop productivity and ensuring global food security. Two primary nutrients in fertilizers are potassium (K+) and nitrate (NO3-), which are vital for proper plant function. In order to formulate better approaches in optimizing…

A foundation of modern biotechnology is the ability to stably introduce foreign DNA into an organism. The two most widely used methods, Agrobacterium-mediated transformation and biolistics, are both steeped in a rich history of creative exploration into the molecular unknown. Agrobacterium research accelerated…

Plants compete with each other over finite resources like water and nutrients, but also for sunlight when they grow in each other’s shadow. Light filtered through leaves is rich in far-red light and initiates responses, known as shade avoidance syndrome (SAS), that aim to out-compete neighbors by promoting…

MicroRNAs (miRNAs) are short (typically 21–22 nucleotide), single-stranded noncoding RNAs that regulate gene expression, mainly via posttranscriptional gene silencing. The miRNA biogenesis pathway is complex, involving numerous proteins, and is highly conserved in plants. If this pathway is hampered,…

When animals are stressed by unfavorable environmental conditions, they will typically move to a more favorable location to reduce that stress. Unfortunately for plants, they are quite literally rooted to the ground and thus must manage the stress where they stand. In order to deal with adverse environmental…

Legumes associate with beneficial soil bacteria called rhizobia to acquire plant-usable ammonia in a process called root nodule symbiosis (RNS). This association is so valuable for nitrogen starved legumes that they form specialized new organs to house them. These de novo organs, called nodules, develop…

Although a vineyard full of decaying grapes infected with noble rot is a blessing for sweet wine producers, the causal agent, Botrytis cinerea (gray mold), causes huge crop losses. Unlike most plant pathogens, individual isolates of the necrotrophic fungus can infect an extremely broad range of plants,…

To optimize their fitness in the field, plants need to respond rapidly, specifically and dynamically to an ever-changing and often hostile environment. By integrating external environmental cues with endogenous developmental programs, phytohormones play a critical role in the cross-talk between signal…

Invasion of plant tissues by pathogens is well known to activate localized reactive oxygen species (ROS) production and cell death.  However, the sources of ROS production and their role in triggering cell death are enigmatic. A recent study by Dangol et al. (2018) shows that, in rice (Oryza sativa),…

Plants need to strike a fine balance between the production, transport, and degradation of stress signals in order to optimize growth in fluctuating environmental conditions. The signal 3’phosphoadenosine 5’phosphate (PAP) accumulates during drought and light stress and induces stress-responsive…

Abiotic stresses constitute a global threat to agricultural crop production and natural ecosystems. One of the most prominent abiotic stresses is drought, which dramatically alters plant physiology and morphology. Studies in model organisms have shed light into how plants respond to drought stress, including…

Of all plant behaviors, ectopic embryogenesis (reviewed in Radoeva and Weijers, 2014) might be one of the coolest. Zygotic embryogenesis begins with fertilization, followed by an asymmetric cell division that generates two cells with distinct fates. The small apical cell gives rise to the pro-embryo,…

Plant stomatal aperture regulation via guard cells is an example of how plants dynamically process environmental signals to induce a physiological response. The drought stress hormone abscisic acid (ABA) is a well-characterized signal that induces stomatal closure, preventing water loss. ABA acts via…

The phytohormone abscisic acid (ABA) regulates a variety of processes in plants including seed dormancy, seedling growth, and response to environmental stresses. A fascinating study by Ni et al. (2018) shows that ABA responses in rice are regulated by an interaction between the DMI3 kinase, which activates…

Anyone who works on plants should be dazzled by the complexity and versatility of plant metabolism. In fact, why restrict this to plant biologists? We all love plant metabolites, whether we’re enjoying the caffeine in our morning cup of tea, or the capsaicin heat in the pepper flakes on our lunchtime…

Resurrection plants have the unique ability to survive extreme dehydration (desiccation), lying dormant for months or sometimes years until rehydration is possible. This formidable survival strategy has independently evolved several times across the land plant phylogeny, and several phylogenetically…

The soil-borne pathogen Plasmodiophora brassicae can infect most members of the Brassicaceae family. The infections, which can lead to extensive crop losses, typically involve development of galls in the underground tissues of the plant, giving the pathogen its common name, ‘clubroot’. Although…

Calcium (Ca2+) is a versatile second messenger that controls a range of cellular processes—from pollen tube growth to stress responses—by regulating the activity of various proteins. Although Ca2+ is present at millimolar concentrations in the cell wall and vacuole, a set of channels, pumps, and…

The endosperm of maize (Zea mays) seeds undergoes a complicated developmental program that ends with the production of massive amounts of storage compounds, particularly carbohydrates, but also including zein storage proteins (reviewed in Li and Berger, 2012; Hannah and Boehlein, 2017; Larkins et al.,…

A pollen grain lands on a stigma, swells with water, and sprouts a pollen tube, which races through the style to deliver sperm to the ovule below. When the pollen arises from the flower itself, this process often stops in its tracks. Self-incompatibility (SI) between pollen and pistil promotes outcrossing…

Thousands of years of artificial selection have produced rice plants (Oryza sativa) that are vastly different from their wild progenitor species in terms of architecture, yield, and resilience. Most of the genetic changes linked to rice domestication involved genes encoding transcription factors. However,…

Although secondary cell walls represent the bulk of plant biomass, the mechanism by which cellulose, hemicellulose, and lignin assemble into a functional three-dimensional matrix is unknown. Cortical microtubules are thought to guide cellulose deposition in the plasma membrane by defining the trajectories…

Plants balance CO2 uptake with water loss via a complex network of signals regulating stomatal aperture size. Stomata close in response to a number of stimuli, including drought, low light intensity, low air humidity, elevated intercellular CO2 concentration, pathogens, and certain air-borne chemicals…

Most chloroplast proteins are encoded by the nuclear genome and synthesized on cytosolic ribosomes. N-terminal transit peptides serve as targeting sequences to direct precursors of chloroplast proteins to receptors on the chloroplast surface. These receptors are part of the translocase of the outer envelope,…

To survive, organisms must sense their nutritional status (including nutrient availability and quality) and regulate their growth and metabolism accordingly. In plants, animals, and fungi, the Target of Rapamycin (TOR) kinase regulates metabolism, nutrient sensing, and growth (reviewed in Dobrenel et…

Sorghum (Sorghum bicolor) is the fifth most important cereal crop globally and is considered to be the “camel among crops” due to its ability to flourish in low-nutrient soils and to withstand prolonged drought. Cultivated varieties are phenotypically and morphological diverse. Consequently, sorghum…

The plant immune system is effective in conferring resistance to various invading pathogens and pests. Membrane-localized pattern recognition receptors (PRRs) and intracellular nucleotide-binding domain, leucine-rich repeat proteins (NLRs) recognize pathogen-associated molecular patterns and pathogen…

Going grocery-shopping on an empty stomach is a bad idea. You’re bound to make poor decisions, not based on nutritional content of the food but based on temporary cravings that will leave you asking for more later. Plants face this nutritional puzzle every day, since they eat where they shop, and shop…

Plants must accommodate many stresses in order to grow and reproduce normally. Heat stress in particular can negatively affect anther development in flowering plants, leading to male-sterile flowers that produce indehiscent anthers and sterile pollen, and consequently are not capable of sexual reproduction.…

Studies of flower development have lots of information about petals, carpels, and stamens, but let’s not forget the birds and the bees—and the flies and moths—and what draws pollinators to insect-pollinated flowers, including flower color, shape, and rewards that provide energy. For example, to…

Finding genes that function in plant development often requires mutant screening, but probing the wealth of natural variation can provide important insights as well. A major focus of developmental biology is uncovering the mechanism behind cell polarity, that is, how components are deposited asymmetrically…

Every plant organ, from tuber to tepal, is formed by cells that divide along precisely placed cell plates. While much is known about the molecular biology behind cell plate formation (e.g., Gu et al., 2016), why cells divide where they do is much less clear. Dividing cells have much in common with soap…

Once viewed merely as inert packets of metabolic energy that are mobilized during postgerminative growth, lipid droplets (LDs) have emerged as dynamic organelles with important roles in processes ranging from stress responses to hormone signaling (Pyc et al., 2017). LDs consist of a core of neutral lipids…

Most proteins within a cell are encoded in the nucleus and then translated in the cytosol, but how do they end up where they need to be? With the exception of the few proteins expressed within the chloroplast, the process of shipping nucleus-encoded proteins into the chloroplast is dependent on N-terminal…

As plant biologists, we do love to consider the physiological adaptations plants have made to being sessile organisms—unlike animals, plants cannot move away from adverse environmental conditions such as high temperature, etc. We commonly consider such responses for organisms, but what about genes?…

Plants integrate signals in the form of light, humidity, temperature, CO2 concentrations and daily circadian rhythms. In addition, plants encounter pathogens, pests, herbivores and other stressors. Physiological processes like responding to stimuli, plant growth and development are usually governed and…

Global climate change is one of the most pressing issues facing our world today. The impact of increasing temperatures can be felt in diverse areas, including human health and disease, natural ecosystems, and food security. In the agricultural sector, deciphering how plants respond to changing environmental…

Apple (Malus x domestica) is a major fruit crop worldwide that faces production losses due to many pathogens. Among them, Alternaria alternata is a fungal pathogen that causes necrotic leaf spots (see Figure), defoliation, and moldy fruit cores and constitutes a serious threat to orchards. Different…

The ATP synthase complex of chloroplasts is an elegant example of the union of structure and function at the molecular level (Junge and Nelson, 2015). This enzyme complex consists of an integral membrane CFo component that transports protons and an extrinsic CF1 component that synthesizes ATP (Hahn et…

Given the importance of branch angle in determining overall plant form, we know surprisingly little about how those angles are controlled. Branch angle clearly has genetic underpinnings but also responds strongly to light and gravity, as well as to water availability and other stimuli (reviewed in Roychoudhry…

The microtubule (MT) cytoskeleton is a dynamic network of self-assembling highways that, together with the help of motor proteins, promotes intracellular transport and the formation of magnificent structures such as the preprophase band, mitotic spindle, and phragmoplast (Nebenführ and Dixit, 2018). …

Some proteins are put to work in more than one job, in a form of evolutionary improvization. They are often described as "moonlighting" proteins, referring to the practice of people taking a second job, typically after dark, to help pay the bills.  A classic example of a moonlighting protein is the…

Plants in temperate regions experience near-freezing temperatures that allow them to develop a cold response prior to freezing. This cold acclimation process involves changes to chromatin structure, transcription, RNA processing, translation, post-translational modifications and protein stability. Genome-wide…

Humans have domesticated crops for thousand of years by artificially selecting plants for numerous traits including morphology, lower toxicity or higher yield. As a result, plant domestication often altered plant fitness and resistance to stress under controlled conditions (Meyer & Purugganan 2013).…

Nutrients are rarely distributed homogenously in soil. Consequently, plants have local and long-distance signaling systems in place to monitor and coordinate both demand and supply of essential macronutrients such as nitrogen (N). The “N-demand” long distance signal emanates from a section of the…

How often does evolution repeat itself? When the same evolutionary strategy arises multiple times, how often are these strategies built on the same genetic foundations? Addressing this question allows us to understand the relative roles of constraint and contingency in the history of life, but (without…

Pollen tubes are remarkable vehicles that deliver immobile sperm nuclei from the stigma to the ovule during angiosperm reproduction. Their journey delicately balances turgor pressure with the precise spatiotemporal regulation of polarized growth machinery to navigate pollen tubes and their cargo to the…

Inorganic phosphate (PPi) is a byproduct of many metabolic reactions, including those involved in sucrose, sugar nucleotide, and cellulose biosynthesis. Although PPi is an important phosphate donor and source of cellular energy, high levels of cytosolic PPi are toxic, disrupting the metabolic reactions…

The story behind m6A (methylation of the N6 position of adenosine), the most common internal mRNA modification in eukaryotes, has long been a source of intrigue. This epitranscriptomic mark is deposited at specific mRNA sequences by m6A writers and removed by m6A erasers. The m6A marks recruit and anchor…

Crosstalk, crosstalk— it’s a word that keeps coming up. Indeed, and perhaps not surprisingly, plant hormone signaling pathways all seem to affect each other to some extent. For example, the MYC2 transcription factor plays roles in abscisic acid (ABA) and jasmonic acid (JA) signaling in the response…

Cell division is essential for growth and reproduction. The cell cycle machinery is well conserved between yeast and animals, but whether this conservation extends to the plant lineage is not clear, having diverged over two billion years ago: ample time and opportunity for divergence in sequence and…

By Peter Ulvskov and Jesper Harholt For the first time in a very long time, a new polysaccharide is reported in plants. Roberts et al. (2018) discovered an arabinoglucan in the moss Physcomitrella patens. This discovery came about not as a result of biochemical characterization of the moss cell…

From the human perspective, separate sexes are the norm while hermaphroditism is an exotic concept. For plants, hermaphroditism is the norm. Dioecy, separate male and female individuals, is rare and dispersed in the angiosperm phylogeny (Käfer et al 2017, Renner 2014). In fact, dioecy is rare enough…

Although they lack eyes, plants can differentiate between colors with a full complement of photoreceptors. Phytochromes (phys) are such photoreceptors dedicated to the visible light spectrum ranging from red light (600-700 nm) to far-red light (700-750 nm). phys are some of the most studied genes and…

When plants have plenty of room, they can maximize the incoming light by spreading their leaves. However, in modern agricultural fields, plants that hold their leaves upright to decrease mutual shading can be grown at high density. Leaves serve as a reservoir for nitrogen that can be re-mobilized to…

Fungal pathogens such as Botrytis cinerea can cause devastating losses to agricultural crops – ask any strawberry, grape, or tomato grower. To prevent these losses, plants can summon a variety of immune responses by recognizing specific molecules associated with pathogen attack and/or internal damage.…

Eukaryotic genes contain protein-coding exons interspersed with non-coding introns. While introns are usually spliced out of mRNA (often in conjunction with various exons), intron retention usually causes mRNA to remain in the nucleus instead of being exported to the cytoplasm for translation. This process…

Eukaryotes use two major systems for getting rid of unwanted proteins: the ubiquitin proteasome system and autophagy. The proteasome degrades ubiquitinated proteins. Autophagosomal vesicles encapsulate cellular waste and either deliver it to the vacuole or fuse with a lysosome. Animal cells use autophagy…

By C. Robin Buell Unlike molecular biology techniques that are routinely used in individual investigator labs, the high cost of infrastructure historically has resulted in genome sequencing being performed at genome centers in which quality control and quality assessments are a mainstay, and it is…

Approaches to improve final grain production must consider yield stability, that is ways to prevent yield losses. For example, flowering time affects yield and yield stability-- if grains mature late, they may be literally caught out in the cold, as late-season weather turns. Indeed, the application…

In the decades since Agrobacterium tumefaciens was first used as a vector to deliver genetic material into plants (Zambryski et al., 1983), this powerful tool has provided important insights into the biological functions of countless gene products. However, this approach has its shortcomings; in addition…

There are several models we use to conceptualize how plants respond to environmental signals through transcriptional regulation. In perhaps the best-understood model, the perception of some environmental signal flows through one or several mechanisms to a master regulator, often a transcription factor…

Meiosis takes a single, diploid cell and turns it into four haploid spores. The equal distribution of genetic material is critical for genome stability across generations, and relies heavily on proper pairing of chromosomes and their timely release. During the first meiotic division, crossovers (COs)…

Partner selection is a critical step that must occur early during establishment of Root Nodule Symbiosis (RNS). RNS refers to the mutualistic interaction between legumes and some non-legumes with soil bacteria that help convert atmospheric nitrogen into plant usable ammonia. In legumes such as Medicago…

As a biotrophic fungus, Ustilago maydis (corn smut fungus) relies on living plant tissues for sustenance. Once U. maydis cells of compatible mating types fuse on a leaf surface, they produce a dikaryotic filament with a specialized infection structure—the appressorium—that penetrates epidermal cells.…

Cyclins and cyclin-dependent protein kinases (CDKs) are critical regulators of cell cycle progression. Although CDK1 is essential for mitosis in animals and fungi, CDKA, the plant and algal ortholog of CDK1, is not essential for cell division in Arabidopsis (Nowack et al., 2012). By contrast, CDKB is…

Approximately half of all ethylene-responsive genes are downregulated in the presence in ethylene (Chang et al, 2013), but this repression has received relatively little attention compared to the ethylene-mediated activation of expression. The known positive regulators of ethylene signaling include ETHYLENE…

Histones undergo myriad covalent modifications - more than 100 types have been identified in the 50+ years since Allfrey, Faulkner, and Mirsky (1964) found that increased histone acetylation was associated with genomic regions of active transcription (reviewed in Zentner and Henikoff, 2013). Enzymes…

Roots grow into new regions of the soil in their constant quest for water and dissolved minerals. This crucial task is made possible by the root meristem and stem cell niche, where neatly arranged stem cells quickly divide beneath a protective root cap. Stem cells give rise to transit amplifying cells,…

Polycomb-group (PcG) proteins are part of an epigenetic memory system that regulates global gene expression throughout development in multicellular eukaryotes (Butenko and Ohad, 2011). Sophisticated mechanisms recruit high molecular weight complexes of PcG proteins to specific targets in the genome.…

In plants, the balance between stem cell renewal and loss is carefully maintained by intricate regulatory networks. Although the root and shoot apical meristems can in principle continue to grow and self-renew indefinitely, the floral meristem is terminated once flower formation is completed. The precise…

Polarization may be bad for civil discourse, but sometimes polarization can be good—for example, if you’re a multicellular organism setting its body axes. In many organisms, polarity within the zygote sets the stage for an asymmetric cell division that defines the apical-basal polarity of the developing…

Plants have two major ways of dealing with drought stress. First, when water levels are low, the phytohormone abscisic acid (ABA) induces stomatal closure. Soon after, growth, flowering, and fruit development take a back seat to plant survival. This suppressed growth is mediated by decreased activity…

The C-terminal domain (CTD) of RNA polymerase II (Pol II) extends from the catalytic core and consists of repeats of a seven-amino acid motif. The CTD functions in the regulation of Pol II function and is subject to just about every protein modification you can think of, including methylation, acetylation,…

The assassin who injects a bead of poison by stabbing his victim with the tip of his umbrella has got nothing on plant pathogenic bacteria such as Pseudomonas syringae, which injects dozens of effector proteins into plant cells. These effectors act as tiny assassins to take out host defenses by diverse…

What do photosynthesis, neonatal jaundice, and a next-generation solar cell have in common? All involve tetrapyrroles, complex molecules with four linked pyrrole rings, each ring containing one nitrogen and four carbon atoms. Tetrapyrroles exist in either cyclic or linear form and have a wide variety…

The next generation of next-generation sequencing is upon us. Third-generation sequencing aims to provide long stretches of sequence – ultimately to the chromosome level – at bargain basement prices. Progress is being made toward those goals with the emergence of long-read sequencing techniques and…

A beam of sunlight sends Chlamydomonas reinhardtii scrambling. This tiny, biflagellate alga senses light with its eyespot and adjusts its movements accordingly, depending on photosynthetic needs. In the eyespot, a membranous structure of reddish, carotenoid-filled granules that reflect light and two…

Fans of the television show The Magic Schoolbus might remember that the teacher/heroine, Ms. Frizzle used to tell her students “Your job, as scientists, is to look for connections!” Ms. Frizzle would love the Mos4-associated Complex (MAC), because MAC has connections all over the place. Indeed, research…

Plant growth and development are extremely adaptable to changes in the external environment, including nutrient status, light quality and intensity, and temperature. Thanks to their developmental plasticity, plants can also initiate new organs from differentiated tissue following wounding, to the benefit…

The energetically costly tendency of the carbon fixing enzyme RuBisCO to, every now and then, fix oxygen instead of carbon dioxide has led to the evolution of various carbon concentrating mechanisms in plants and algae. One such mechanism, Crassulacean acid metabolism (CAM), involves primary CO2 fixation…

Aphids are highly destructive insect pests—in addition to robbing plants of sugar-rich phloem sap, they carry viruses that can be deadly to the plant. To reach the phloem sap, aphids must penetrate the plasma membrane of sieve elements. Mature sieve elements, which are virtually empty, translocate…

A hallmark of xylem development is the deposition of secondary cell wall material in specific patterns (reviewed in Patrick et al, 2007). These cell wall deposits structurally reinforce the xylem to withstand negative pressure during water transport and differ in different xylem cell types. While it…

We all know that DNA is the stable nucleic acid, in comparison to its flighty, unstable cousin RNA, right? Well, unusual things happen when metabolic processes require DNA to unwind from its stable, redundant double-helical form. For example, during transcription, the RNA that exits RNA polymerase can…

Folates are soluble B9 vitamins with essential functions in all kingdoms of life—both in organisms that produce these vitamins de novo (fungi, plants, and most microorganisms) and in those that do not (animals). As essential cofactors in one-carbon transfers, different folate species mediate the biosynthesis…

The ability to acclimate to high temperatures that are normally lethal is common to virtually all organisms on the planet. A short exposure to milder heat stress informs organisms that they should ready themselves in case they experience even warmer conditions. Acquired thermo-tolerance in plants is…

The ever-increasing amount of data available to researchers has come with similarly increasing cognitive loads in efforts to use these data. Even when data sets are stored in well-curated databases, it can be time-consuming to master the specific tools harbored at each site and cumbersome to move between…

Carbon and nitrogen metabolism are intricately linked in all organisms and are tightly regulated to maintain growth, homeostasis, and other cellular activities. In plants and algae, photosynthesis provides both carbon skeletons and the reductant needed for assimilation of inorganic NO3¯ by nitrate reductase…

The canonical auxin-response pathway in plants begins with auxin sensing by F-box proteins, triggering degradation of AUX/IAA proteins that act as transcriptional repressors via their interaction with sequence-specific DNA-binding AUXIN RESPONSE FACTORS (ARFs; reviewed in Weijers and Wagner, 2016).  Recently,…

During meiosis, recombination between allelic sequences on pairs of homologous chromosomes forms crossovers; these crossovers help make sure that the homologs segregate accurately (reviewed in Zhang et al., 2014). However, cells must suppress recombination between non-allelic sequences, as ectopic recombination…

Ornamental grasses with a sprawling growth habit may be welcome in the garden, but grasses such as maize (Zea mays) give the highest yields when they exhibit upright leaf architecture, allowing them to be planted at high density while maximizing their exposure to sunlight. The maize leaf is composed…

A lot of effort goes into making a flower. Suites of genes must function in the right place at the right time. If not, stamens might grow where sepals should be, and so on, yielding homeotic mutant flowers. In general, flower parts are arranged in four concentric whorls of organs, including (from outside…

Isoprenoids are a huge group of compounds that include primary metabolites such as carotenoids, chlorophylls, and hormones, as well as a plethora of specialized secondary metabolites. In addition to their importance in the physiology of plants (and of other kingdoms of life), isoprenoids have drawn attention…

One of the central players in the complex regulation of flowering, CONSTANS (CO) functions as a center for integration of the various signals that determine the timing of flowering. As output, CO regulates the expression of FLOWERING LOCUS T (FT) and other genes (reviewed by Shim et al., 2017). CO contains…

Systemic acquired resistance (SAR)—a plant-wide heightened state of defense following localized exposure to a pathogen—is characterized by increased salicylic acid (SA) and ROS levels and elevated expression of pathogenesis-related genes. SAR depends on ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), which…

Eukaryotic pathogens are responsible for devastating plant diseases that threaten food supplies globally – think potato blight caused by the oomycete Phytophora infestans, rice blast caused by the fungus Magnaporthe oryzae, and wheat stem rust caused by the fungus Puccinia graminis f. sp. tritici.…

Obtaining genomics and other –omics datasets is now routine and widely used across all biological systems, including plants. As a consequence, a wide range of plant species are being interrogated at the genome, epigenome, transcriptome, translatome, and proteome level, leading to new hypotheses about…

Soon after dicots germinate, the hypocotyl arches into a hook-like structure that protects the shoot apical meristem as the seedling grows through the soil. Once the seedling emerges from the ground and senses light, the hypocotyl straightens. The asymmetric growth that results in apical hook formation…

Once seen as potential sequencing artifacts, long, non-coding RNAs (lncRNAs, >200 nucleotides) have gained recognition as important regulatory factors. LncRNAs are transcribed from a variety of genomic locations (introns, intergenic spaces, and coding regions) from the sense or antisense strand (reviewed…

During vegetative growth, the shoot apical meristem (SAM) produces lateral organ primordia but remains roughly the same size, as WUSCHEL–CLAVATA signaling modulates the balance between cell division and differentiation. During the transition to reproductive growth in many species, the SAM expands in…

Plants produce scores of specialized metabolites (SMs) to attract or repel the organisms around them and to cope with life in a variable environment. For thousands of years, we have been exploiting these compounds to feed, heal, and adorn us. Many more SMs remain to be discovered: the chemical constituents…

Tender green leaves and tasty tubers, roots, and stems are vulnerable to a wide range of pathogens, pests, and herbivores. Perhaps it should not be surprising that they have evolved an equally wide range of defense mechanisms. This issue of The Plant Cell includes reviews of just a few of the many facets…

Most soybean seeds you see, whether in bins at the store, or in train cars as a commodity crop, have a yellow seed coat that may have only a tiny fleck of dark pigment at the hilum, where the seed attaches to the pod. The predominant yellow color results from silencing of chalcone synthase (CHS) genes…

IN BRIEF by Jennifer Lockhart [email protected] Plant cell components that are no longer needed are degraded in the vacuole, but they don’t get there by magic. Sack-like double-membrane structures called autophagosomes engulf this cellular rubbish and neatly transport it to the vacuole for degradation.…

IN BRIEF by Gregory Bertoni [email protected] Proper localization of proteins in the plasma membrane is critical for proper functioning of plant cells, but the underlying mechanisms are poorly understood (Łangowski et al, 2016). This is especially true for transporter proteins that move necessary…

IN BRIEF by Nancy R. Hofmann [email protected] The economy of living cells includes energy production, energy utilization, and energy storage. Thus, a plant’s energy budget must connect the decision to produce lipids (for energy storage) with its overall energy status. Energy sensor kinases, such…

IN BRIEF by Jennifer Mach [email protected] To navigate its essential function of producing mRNAs, RNA polymerase II (Pol II) must navigate the thread of DNA, which winds around thousands of nucleosomes. If you’ve ever tried to use a sewing machine but got your bobbin thread tangled, then the task faced…

IN BRIEF by Gregory Bertoni [email protected] Autophagy, or "self eating," is the process cells use to consume unwanted intracellular structures such as damaged organelles, excess membranes, and unneeded cellular proteins (Mizushima and Komatsu, 2011). Typically, the unwanted structure becomes surrounded…

IN BRIEF by Jennifer Lockhart [email protected] The interior of a plant cell is supported by the actin cytoskeleton, a complex network of yarn-like fibers whose form changes as the cell develops, grows, and divides. Actin fibers readily come apart (sever) and join back together, depending on the…

IN BRIEF: Nancy R. Hofmann [email protected] Plant development and responses to the environment hinge on the ability to target proteins to different areas of the plasma membrane within a cell. Indeed, the establishment of polar distributions of proteins such as PIN auxin transporters is among the…

IN BRIEF by Kathleen L. Farquharson [email protected] Limiting shoot growth is an important survival strategy for plants during times of drought; smaller leaves mean that less water is lost through transpiration and more is retained in the soil. As drought stress restricts both cell division and…

IN BRIEF by Jennifer Lockhart [email protected] DNA is sculpted by several types of epigenetic modifications with profound effects on gene expression, development, and stress responses. Much less is known about the more than 100 chemical modifications shaping plant RNA, a topic explored in the newly…

IN BRIEF by Jennifer Mach [email protected] Green may have been the Pantone Color of the Year for 2013 (http://www.pantone.com/color-of-the-year-2013), but 2016 was a great year for papers on chlorophyll research, at The Plant Cell and beyond. In this year, we saw a pile of interesting papers examining…

IN BRIEF by Jennifer Lockhart [email protected] Most plants are hermaphrodites, producing perfect flowers with both male and female functions. In roughly 6% of plants, however, male (usually XY) plants produce only male flowers and female (XX) plants produce only female flowers. These dioecious plants…

IN BRIEF by Kathleen L. Farquharson [email protected] Alternative splicing (AS) regulates gene expression and greatly expands the coding capacity of complex genomes. By regulating which elements of an mRNA transcript are removed or retained, AS produces multiple transcripts from a single gene. Some…

IN BRIEF by Nancy R. Hofmann [email protected] A new study calls into question whether phytochrome B (phyB) must directly interact with phytochrome-interacting factors (PIFs) to promote light responses. Phytochrome photoreceptors mediate responses to red light in part by inducing the degradation of…

IN BRIEF by Gregory Bertoni [email protected] RNA metabolism is key to a number of crucial processes in the cell, including transcription, RNA splicing, translation, and gene regulation. For efficient translation, mature mRNAs must have a 7-methylguanosine cap on the 5′ end to help recruit the translation…

IN BRIEF by Nancy R. Hofmann  [email protected] Plant cell walls consist of cellulose microfibrils embedded in a matrix of polymers including hemicelluloses. As one of the main hemicelluloses in the cell walls of dicots, xyloglucan is an important target of study to understand plant cell walls…

IN BRIEF by Jennifer Mach [email protected] Plants can dispose of organs such as leaves and recycle the nutrients in these organs into new leaves, seeds, or storage organs. However, when separated from its photosystem proteins, chlorophyll can be phototoxic, absorbing light and producing high-energy…

IN BRIEF by Jennifer Lockhart [email protected] Heat and drought stress greatly restrict crop productivity, but most of what we know about a plant’s response to these stresses comes from controlled laboratory studies. This factor, along with the complex nature of these responses, has hampered efforts…

IN BRIEF by Nancy Hofmann [email protected] The ability to generate transgenic plants without regard to cultivar or genotype can be considered a holy grail of cereal crop transformation. Despite years of effort, it has been remarkably difficult to develop efficient methods for transformation of…

IN BRIEF by Jennifer Mach [email protected] Assessing protein-protein interactions remains a fundamental challenge for plant biologists. Current methods such as coimmunoprecipitation (co-IP), yeast two-hybrid, bimolecular fluorescence complementation (BiFC), and others can produce artifacts and also yield…

IN BRIEF by Kathleen L. Farquharson [email protected] Polysaccharide-rich cell walls are a distinguishing feature of plants that influence many aspects of growth and development, including cell division. Whereas contractile rings pinch dividing cells into two daughter cells in other eukaryotes,…

IN BRIEF by Nancy Hofmann [email protected] Most bacteria have a peptidoglycan layer between the inner and outer membranes (reviewed in Typas et al., 2012). The cyanobacterial endosymbiont that gave rise to plastids would have contained such a peptidoglycan wall including d-amino acids. Indeed, peptidoglycan…

IN BRIEF by Jennifer Lockhart [email protected] When a deer eats the primary shoot of a plant, this can activate a nearby dormant axillary bud, causing it to form a secondary shoot. Genetic and environmental factors also affect shoot architecture, which strongly influences crop productivity. Changes…

IN BRIEF by Jennifer Mach [email protected] Movement of macromolecules through the plant phloem provides a mechanism for long-distance signaling that plants use in development, disease resistance, and other adaptive responses (reviewed in Spiegelman et al., 2013). For example, full-length RNAs, such…