Tag: Photosynthesis

Photosynthesis is fundamental to life on Earth and a topic that all plant biologists should have a good understanding of, but it is also an incredibly complex set of processes, reactions and structures spanning great temporal and spatial distances. In this new Commentary by Eckardt et al., several experts…

Pyrenoids are structures that concentrate carbon dioxide around Rubisco, most commonly studied in green algae such as Chlamydomonas. However, hornworts, one of the three types of bryophytes (along with liverworts and mosses) also have a pyrenoid-based CO2-concentrating mechanism (pCCM), unique among…

In the dazzling dance of plant cellular life, chloroplasts must groove in harmony with growth to sidestep the perils of photooxidative damage. This harmony between photosynthesis and photooxidative damage is orchestrated by the guanosine tetraphosphate (ppGpp) signalling pathway which traces its roots…

Xin et al. determined the cryo-EM structure of HQNO-bound Alternative Complex III from the anoxygenic phototrophic bacterium Chloroflexus aurantiacus. The Plant Cell (2024) https://doi.org/10.1093/plcell/koae029 By Xiaoling Xu at Hangzhou Normal University, Hangzhou, China Background: Photosynthesis…

Photosynthesis is the process by which plants assimilate carbon by using light energy. However, with the solar energy conversion efficiency of many crop plants less than 1%, it is inefficient. Therefore, there is interest in manipulating photosynthesis for increased efficiency. Here, Croce et al. identifying…

In woody plants, we know much less about how photosynthesis functions in stems than in leaves. This study by Natale et al. focused on how chloroplasts in Fraxinus ornus stems of different ages work. The authors looked at oxygen production rates in whole stems, bark, and wood using various methods like…

Healthy plants require access to several mineral nutrients, which are usually taken up in ionic form. The details of nutrient uptake, distribution, and function have been painstakingly revealed over several decades. In this excellent new Tansley Review, Kunz et al. provide an overview of ion homeostasis…

I remember how amazed I was the first time I saw an animation of ATP synthase doing its job. This fantastic engine is largely conserved across the domains of life, with some variation as highlighted in this review of the chloroplast ATP synthase by Rühle et al. The plastid form is a rotary form, written…

In the dark, plants modify thylakoid stacking to alter electron transport and reduce photodamage. More photosystem II (PSII) is located in thylakoids within stacked grana, which promotes cyclic electron transport. Upon light exposure, there is granal unstacking, which increases the amount of linear electron…

Plants that use C4 photosynthesis, whereby carbon is concentrated around RuBisCo in bundle sheath cells, have high water and nitrogen use efficiencies. Thus, understanding how C4 photosynthesis evolves is of much interest. The Flaveria genus provides a unique opportunity for this, as it contains species…

Imagine the everyday delights of foods like bread, ramen, or sushi. Central to these culinary staples is starch, a product of the photosynthesis process in plants. Despite its critical role, people still do not fully understand the regulation and biogenesis of the photosynthesis machinery. In this study,…

Sometime in the Cretaceous period (dinosaur time!), some monocots acquired a special pathway for carbon fixation, rendering them more efficient particularly in hot or dry environments. In most monocots, carbon is fixed by Rubisco in the mesophyll cells. In the innovative pathway, carbon fixation is split…

Enhancing crop yield for future food supplies involves increasing photosynthetic efficiency, which can be achieved by improving photoprotection through non-photochemical quenching (NPQ). NPQ enables leaves to dissipate excess absorbed light energy as heat, minimizing the negative effects of photodamage.…

C4 photosynthesis is derived from C3 photosynthesis. When related genes are compared, those involved in C4 photosynthesis tend to be more highly expressed. To understand this phenomenon, Singh et al. undertook a very impressive approach to look at transcriptional regulation of essentially all the photosynthetic…

Photosynthesis is the major process which supports plant survival. It’s the kitchen serving food (sugars) to the plant by converting the light energy. Leaves are the major site of photosynthesis for most plants. However, certain plants evolved unconventional ways of performing photosynthesis. In a…

Reiter et al. investigate the molecular basis for coupling factor CF1 recruitment in Arabidopsis thaliana. The Plant Cell (2022). By Thilo Rühle Background: Thylakoid ATP synthases are impressive molecular engines that harness the light-driven proton gradient to generate ATP during photosynthesis.…

Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase) is one of a kind, simultaneously recognized as one of the most abundant and important enzymes, and also widely characterized as flawed because it uses both O2 and CO2 as substrates, leading to both carboxylation and oxygenation of ribulose bisphosphate.…

Chloroplasts divide by binary fission driven by a protein ring, the position of which is regulated by the Min system (derived from the system in bacteria). The inner envelope membrane protein PARC6 (PARALOG OF ARC6) is a key component. Here Sun et al. generated crystal structures showing that PARC6 interacts…

Rubisco (ribulose-1,5-bisphosphate carboxylase) catalyzes the fixation of atmospheric carbon from CO2 to molecules used for biosynthesis and energy production. Several studies have focused on understanding the nature, complexity, activity, and regulation of Rubisco due to its key role in the production…

Procko et al. investigate the molecular identities of specialized photosynthetic cell types in leaves. https://doi.org/10.1093/plcell/koac167 By Carl Procko and Travis Lee. Salk Institute for Biological Studies, CA Background: Photosynthesis is arguably the most important biochemical process…

C4 and CAM are both photosynthetic strategies that concentrate CO2 upstream of RuBisCO, somewhat uncoupling photosynthetic carbon fixation from transpirational water loss. Both strategies use the enzyme PEP-carboxylase to produce an organic acid, which can then be decarboxylated to provide CO2 to RuBisCO.…

Choi et al. report that the Chlamydomonas bZIP transcription factor BLZ8 induces the carbon-concentrating mechanism to provide an electron sink pathway, reducing reactive oxygen species production under oxidative stress conditions. Plant Cell. https://doi.org/10.1093/plcell/koab293 By Bae Young Choi,…

Leaves are the specialized organs of the plant that have evolved to maximize the use of light and CO2 for efficient photosynthesis. Although knowledge of photosynthesis has exploded recently, the molecular intricacies underlying leaf anatomy, especially mesophyll, remains unravelled. The palisade mesophyll…

Plants must adjust to varying levels of light in order to optimize photosynthetic rates; too little electron transport and plants will incur an energetic penalty, while excessive excitation of photosystem I leads to photodamage. During high light conditions, the increase in DpH acts as a brake on electron…

Photosynthesis is an attractive target for improving crop yields, and tailoring downstream photosynthesis-associated metabolism is a relatively unexplored path for achieving this. Chlorella ohadii is the fastest growing photosynthetic organism identified, has high photosynthetic rates, and can survive…

Despite a large variation in leaf morphology, laminar leaf anatomy is largely conserved, comprising two developmentally distinct mesophyll tissues, the palisade and spongy mesophyll. Spongy mesophyll cells along with intercellular spaces form an interconnected network to maximize the surface area for…

Ostermeier et al. introduce AncM, a new factor for structuring the photosynthetic membrane system in cyanobacteria. Plant Cell https://doi.org/10.1093/plcell/koab253 By Matthias Ostermeier, Steffen Heinz and Jörg Nickelsen at Molecular Plant Science at LMU Munich Background: Cyanobacteria are…

Albino plants lack chlorophyll, which means that they cannot photosynthesize. These kinds of plant are unique and can offer information as to the molecular mechanism of chlorophyll degradation and photosynthesis in plants. Here, Arisha et al. explored the differences in gene expression patterns of seedling…

Chloroplasts are indispensable for plant growth and physiological performance; not only for photosynthesis but also for many biochemical processes. Due to the endosymbiont origin of the chloroplast, chloroplast development requires sophisticated machinery to relay the signals between the nuclear and…

Zupok et al. demonstrate that photosynthesis genes encoded on the chloroplast genome can establish hybridization barriers. Plant Cell. (2021)  https://doi.org/10.1093/plcell/koab155 By Arkadiusz Zupok, Danijela Kozul and Stephan Greiner, Max Planck Institute of Molecular Plant Physiology, Potsdam/Golm,…

DeTar et al. examined whether disruption of ion homeostasis affects plastid gene expression and chloroplast development. Rachael Ann DeTar and Hans-Henning Kunz both at School of Biological Sciences at Washington State University & Plant Biochemistry at LMU Munich Background: Proteins that…

Haber et al. developed an automated microplate system to continuously monitor levels of reactive oxygen species in planta. Plant Cell. https://doi.org/10.1093/plcell/koab068. By Zechariah Haber and Shilo Rosenwasser, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The…

Photosystem II is a multisubunit enzyme complex in the thylakoid membranes of plant, algae, and cyanobacteria. Here, Zebret et al. used cryo-electron microscopy to produce high-resolution structural information of the intermediate complexes involved in the biogenesis and assembly of photosystem II from…

Has crop photosynthesis research been successful for increasing yields? This very crucial question is analyzed in a new review by Araus et al. The authors report that there has been no increase that can be described as a "quantum leap," but they discuss the merits of increasing leaf photosynthesis and…

By Patrice Salomé, Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA  Salomé and Merchant analyze hundreds of RNA-seq samples in the single-cell green alga and discover vast co-expression potential and surprising residual synchronized expression across samples derived from cultures…

Algae powered by red algal-derived plastids (e.g., diatoms, dinoflagellates, and coccolithophores) are among the most evolutionary and ecologically successful eukaryotes on Earth, but their origins and relationships remain poorly understood. Here, Strassert et al. test the rhodoplex hypothesis that designates…

An efficient C4 photosynthetic pathway relies on the coordination between the biochemical carbon concentration mechanism that secures high rates of C4 acid flow into the bundle sheath (BS) and anatomical modifications that minimize CO2 leakage out of the BS cells. Suberin deposition in BS cell walls…

Sipka and coworkers show that the closed state of photosystem II holds a formerly unrecognized structural and functional plasticity and upon illumination assumes a light-adapted charge-separated state. [Plant Cell https://academic.oup.com/plcell/advance-article/doi/10.1093/plcell/koab008/6119330] By…

Hosotani et al. explore the molecular mechanisms that modulate stomatal opening under different light conditions. by Sakurako Hosotani and Atsushi Takemiya (Yamaguchi University)  Background: Opening of stomatal pores is essential for photosynthetic CO2 fixation and transpiration in terrestrial…

Light comes largely from above, and plants have evolved strategies to efficiently capture this light even when competing with other potentially shading plants. However, at a field-level, such competition may (and does) prevent plants from collectively maximizing light use efficiency, hence yield. In…

Three key factors affect a plant’s ability to fix carbon: enzymatic activity of Rubisco, stomatal conductance, and the journey from sub-stomatal cavity to Rubisco, also known as mesophyll conductance (gm). This latter is the focus of this new work by Clarke et al. They delightfully compare this journey…

Redox switches regulate photosynthetic reactions and are mediated by conserved cysteine pairs, activated by reduction under light and deactivated by oxidation in the dark. Those reactions are mediated by thioredoxins (Trx). Usually, only plastidic and not cytosolic isozymes show these redox switches.…

Zhan and Steglich et al. investigate the small RNA-mediated regulation of the photoprotective Orange Carotenoid Protein in cyanobacteria. https://bit.ly/3d3AqY0 By Jiao Zhan1,2, Wolfgang Hess3 and Diana Kirilovsky1 1 Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the…

Efficient phenotyping is important for plant breeding. For wheat, leaf reflectance spectra can be used to calculate leaf traits that impact crop yield, particularly constituent (leaf mass per area, nitrogen/chlorophyll content) and physiological (Rubisco carboxylation activity, electron transport…

Photosynthesis, in addition to generating ‘food’ for plants, is also known to control root growth, although the mechanism has been unknown. Duan and co-workers identified CYCLOPHILIN38 (CYP38) as necessary for photosynthesis-mediated lateral root (LR) emergence. The chloroplast-localized CYP38 is…

There’s been a lot of talk lately about how to improve the carboxylation efficiency of Rubisco, but of course this also depends on how much CO2 reaches the enzyme within the chloroplasts. To do so, it needs to pass through several distinct barriers: the boundary layer to reach the leaf surface, the…

Kasper van Gelderen Utrecht University [email protected] Plants cannot live without light, but they also cannot live with too much light. Beyond a certain threshold, a high light intensity will damage the photosynthetic apparatus directly. Furthermore, high light leads to the production of reactive…

Crassulacean acid metabolism (CAM) is a photosynthetic adaptation pathway in arid environments to minimize water loss by opening the stomata at night, when the temperature and therefore water loss due to transpiration is lower. Carbon dioxide is initially fixed at night and stored in the vacuole. Engineering…

In a rosette-forming plant like Arabidopsis, leaf radial angle is optimized to prevent self-shielding. By contrast, in a plant such as sorghum, leaf vertical angle affects self-shading. A “smart canopy” model has been proposed in which upper leaves have a more upright orientation to allow more light…

Rubisco is a major enzyme in assimilating CO2 during photosynthesis. The efficiency of CO2 assimilation is compromised by a low ratio of CO2/O2, especially in C3 plants like rice, wheat and soybean. Algae sequester Rubisco as a condensate in a microcompartment called a pyrenoid within the chloroplast…

Zhi Li, Andan Zhu, et al. compare inbred and hybrid lines to explore how daily changes in metabolic pathways affect hybrid vigor. The Plant Cell https://doi.org/10.1105/tpc.20.00320  Background: Heterosis or hybrid vigor refers to the superior growth or fitness in the hybrid progeny compared to one…

Photosystem I (PSI) is a membrane-bound protein complex that plays a central role in the conversion of solar energy to chemical energy to drive assimilate production.  Photosystem I is an enzyme complex that transfers electrons from plastocyanin (Pc) to ferredoxin (Fd). Here Caspy et al. have characterized…

Mother Nature has a way of keeping seemingly useless structures around millions of years. Such structures are likely to have a use that is not obvious, although they could also be remnants of the evolutionary past without extant function, or non-functional but harmless byproducts of a different adaptive…

The rate of carboxylation by Rubisco versus the rate of the competing oxygenation reaction limits photosynthesis in some conditions, so many researchers are investigating ways to enhance Rubisco. Rubisco is not limited to green plants but can be found in other lineages including red algae and photosynthetic…

AuBuchon-Elder and Coneva et al. reveal an important function for apparently non-functional floral structures. Plant Cell https://doi.org/10.1105/tpc.20.004242 By Taylor AuBuchon-Elder1,*, Viktoriya Coneva1,2*, Doug K. Allen1,3†, and Elizabeth A. Kellogg1† 1Donald Danforth Plant Science…

Charlotte Gommers, Assistant Features Editor [email protected] For a long time, the study of light fueled two independent fields of plant sciences. On the one hand, light energy is absorbed in the chloroplasts, to drive sugar production via photosynthesis. On the other hand, light is an…

Rubisco is the enzyme responsible for the fixation of CO2 to ribulose-1,5-bisphosphate (RuBP) during photosynthetic reactions. However, this enzyme has some functional issues, such as a slow catalytic turnover rate and sensitivity to temperature and CO2, and it catalyzes a competing oxygenation process…

Ananya Mukherjee University of Nebraska, Lincoln, Nebraska 68588 ORCID ID: 0000-0003-1802-1806 [email protected] Photosynthetic organisms often face fluctuations in light quality and quantity. Green plants and algae have built-in mechanisms that allow them to adapt to such changes. One…

The three most widely adopted plant models all use C3 photosynthesis, but discoveries made in these plants are not always applicable to C­4 plants. Foxtail millet (Setaria italica) has been emerging as a potential C4 model species, but its use for genomics research is challenging due to long generation…

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…

Biofortification aims at increasing the content of health-promoting nutrients in edible parts of the plant. As an example, enhancing the production of carotenoids - natural pigments that provide the yellow to red color – in crops could prevent vitamin A deficiency in humans. In nature, carotenoids…

Yield potential in crops is determined by the efficiency of photosynthetic rates, which is a critical target for improvement. Previous studies have shown that photosynthetic carbon assimilation and plant biomass can be improved by the stimulation of either regeneration of RuBP (the five-carbon sugar…

The green alga Chlorella ohadii was recently isolated from the harsh environment of desert biological sand crusts, where it is able to grow and thrive in extreme conditions. Previously, studies showed that it is unusually resistant to photodamage, even at twice the irradiance of maximal sunlight thanks…

Martin-Avila et al. use synthetic biology to improve photosynthesis in tobacco by swapping out the endogenous small subunits of Rubisco for one coming from potato, among other things. Plant Cell https://doi.org/10.1105/tpc.20.00288 By Spencer Whitney, Elena Martin-Avila, Sally Buck, Timothy Rhodes,…

In an interesting evolutionary artifact, the genes encoding the small subunit of Rubisco, rbcS, reside in the nuclear genome, whilst those encoding RbcL persists in the chloroplast. The RbcS protein is translocated into the chloroplast where the holoenzyme forms. This complexity adds to the challenge…

In linear electron transport (LET), electrons are passed from photosystem II to photosystem I, but it has not been clear which of two mobile electron carriers is responsible, plastocyanin (PC) or plastoquinone (PQ). PQ carries electrons from PSII to the cyt b6f complex and PC from there to PSI. Höhner…

This is a fascinating and very well-written paper that investigates the diversity of rubisco's kinetic properties. Rubisco’s relationship with its substrate CO2 is complicated by its relationship with O2, and it has often been suggested that for this reason rubisco is locked into a slow rate of catalysis.…

Crop production is greatly influenced by the duration of the last stage of plant life cycle, senescence, through degradation of resources in leaves and remobilization of nutrients to developing seeds. Indeed, higher grain yield of important cereals such as maize and sorghum can be achieved by using stay-green…

Plants and green algae can rapidly adapt to changing light conditions. Depending on light availability or other metabolic needs, Light Harvesting Complexes (LHC) II can be reallocated to photosystem I (PSI) from photosystem II (PSII) and vice versa. This is known as state transition and is mediated by…

The thylakoid membranes inside the chloroplasts house the major protein complexes required for photosynthesis, including photosystems I and II (PSI/II), the b6f complex and ATP synthase. To optimize photosynthetic efficiency, the distribution and abundance of these complexes are dynamically regulated…

Photosystem II (PSII) is a protein complex located in the thylakoid membrane of chloroplasts that is involved in executing the initial reaction of photosynthesis in plants. When plants are exposed to extreme temperature conditions, PSII gets damaged. To repair the damage, one of the core proteins of…

The thylakoid membranes are located in the stroma of chloroplasts and house the machinery for the photosynthetic light reactions. They emerge largely de novo during the transition from pro-plastids into mature, photosynthesizing chloroplasts. Generating new thylakoid membranes requires a supply of lipids,…

In stressful situations, such as high light and nutrient scarcity, the chloroplast may experience increased proteotoxicity due to a surge in damaging reactive oxygen species. In response, a signal is sent to the nucleus to increase production of many proteins, including proteases and chaperones to help…

Boxall et al. explore the effects of silencing phosphoenolpyruvate carboxylase in a Crassulacean acid metabolism species. Plant Cell https://doi.org/10.1105/tpc.19.00481 By Susie Boxall and James Hartwell Background: Severe droughts and high temperatures are becoming more frequent due to climate…

Cyanobacteria and red algae employ phycobilisomes (PBSs) as light-harvesting systems to adapt to fluctuating environments. PBSs are composed of phycobiliproteins, linker proteins and chromophores. Ma et al. used cryo-EM to determine the 2.82 Å structure of  the very large (14.7-megadalton, 706 protein…

Angiosperm seeds develop within maternal tissues, yet in some species including Arabidopsis the developing embryos carry out photosynthesis. In Arabidopsis, this is transitory, and the embryonic chloroplasts lose chlorophyll and dedifferentiate into eoplasts as the seed matures. Sela et al. set out to…

Sun et al. reveal the subcellular organization of photosystem biogenesis in Chlamydomonas. Plant Cell https://doi.org/10.1105/tpc.19.00263 by Melissa Valente-Paterno, Yi Sun and William Zerges. Department of Biology, Concordia University.  Background: Cells localize intracellular processes to…

Crassulacean acid metabolism (CAM) is a water-conserving strategy in which stomata open at night and carbon is stored until daytime photosynthesis provides the energy to fix it. This special issue of the Journal of Experimental Botany, edited by Hultine, Cushman, and Williams, brings together a set of…

Some plants such as Zea mays partition different components of the photosynthetic pathway in mesophyll cells (MC) and bundle sheath cells (BSC) in a process known as two-cell C4 photosynthesis. For example, light-harvesting reactions carried out by photosystem I and II (PSI and PSII) occur only in the…

Chromoplasts are a type of plastid, usually found in fruits and flowers, that can accumulate large amounts of carotenoids including beta-carotene (pro-vitamin A). It has been proposed that increasing chromoplast formation could be a way to enhance human consumption of vitamin A. In a new report, Llorente…

Photosynthesis occurs in several ways, only one of which releases oxygen as a product. As oxygen-breathing organisms, we are totally dependent on oxygenic photosynthesis, which is restricted to cyanobacteria and green plant plastids. In this review, Sánchez‐Baracaldo and Cardona examine how recent…

In the 450 million(ish) years since plants acquired the ability to live on land, they have caused dramatic changes in the concentrations of atmospheric CO2 and O2 levels. As an example, due to tremendous increases in photosynthesis, CO2 levels dropped and O2 levels rose dramatically in the late Paleozoic…

Burgess et al characterize genome-wide patterns of transcription factor binding to provide insight into the architecture associated with C4 photosynthesis gene expression. Plant Cell https://doi.org/10.1105/tpc.19.00078 By Steven James Burgess (University of Cambridge, UK) and Ivan A. Reyna-Llorens…

Most plants use the C3 photosynthesis pathway, however many have evolved strategies like C4 photosynthesis that accumulate CO2 around RuBisCO. Burgess et al. performed DNAseI-SEQ in three C4 plants: S. bicolor, Z. mays and S. italica, and one C3: B. dystachion, to offer an insight into the cis-element…

In most eukaryotic algae, carbon fixation takes place in an organelle within an organelle, the pyrenoid inside of the chloroplast. Besides being functionally very important, pyrenoids are interesting because they are what is called a phase-separated structure, that is they are not membrane enclosed;…

Light serves as the source of energy as well as an information signal for photosynthetic plants. During evolution, plants have acquired the ability to monitor environmental light radiation and adjust their developmental patterns to optimally utilize light energy for photosynthesis. However how the early-diverging…

One of the things I like most about synthetic biology is the “why not” attitude. This article by Bernhardsgrütter et al. is intriguing because rather than taking the standard “let’s fix Rubisco approach,” the authors started with a non-CO2 fixing enzyme and engineered it towards having carboxylase…

Sun et al. investigate how carboxysomes are constructed and regulated in cyanobacteria. Plant Cell https://doi.org/10.1105/tpc.18.00787 By Luning Liu Background: All cells are composed of well-defined compartments to encase enzymes and reactions to increase the efficiency of biological processes.…

“Cysteine (HO2CCH(NH2)CH2SH) synthesis is the converging point of the three major pathways of primary metabolism: carbon, nitrate, and sulfate assimilation.” It’s hard enough to coordinate two pathways, let alone three; but these metabolic connections are revealed in that a deficiency in one nutrient…

Roth et al. investigate how a green alga turns photosynthesis off and on when glucose is added and then removed from the culture medium. Plant Cell https://doi.org/10.1105/tpc.18.00742 By Melissa Roth and Krishna Niyogi, University of California-Berkeley Background: Photosynthesis is the life-sustaining…

Crassulacean acid metabolism (CAM) is a carbon fixation pathway that reduces photorespiration and increases water use efficiency, enabling CAM plants to survive in inhospitable environments. The evolution of CAM on 35 independent occasions across angiosperms makes it a notable case study of convergent…

Hai Wang et al. identify a regulator of stomatal movement and photosynthesis. Plant Cell https://doi.org/10.1105/tpc.18.00736 By Hai Wang, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences Background: Fixation of atmospheric CO2 through photosynthesis is crucial for the…

“Earth is a cold place with 80% of its biosphere permanently below 5°C,” begins this study of an Antarctic psychrophile (“cold-lover”). As Szyszka-Mroz et al. indicate, the permanently cold-adapted inhabitants of permanently frozen lakes are highly vulnerable to the effects of climate change,…

With the need to feed the growing population and the threat of global climate change, there is an imminent need to increase crop yields. One commonly accepted method of accomplishing this is by enhancing the photosynthetic capability of major crop plants, which may result in an increased yield. A recent…

Plants often optimize their development according to the prevailing environmental conditions, of which light is one of the most important. Arabidopsis uses a PSI-PSII megacomplex as the photosystem reaction center, to transfer the excessive energy from PSII to PSI rapidly. Recently, Yokono et al. proposed…

Calzadilla et al. investigate the mechanism underlying state transitions in cyanobacteria. Plant Cell https://doi.org/10.1105/tpc.18.00159 By Pablo I. Calzadilla and Diana Kirilovsky, Institute for Integrative Biology of the Cell, CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif sur…

The global population is estimated to rise by 2 billion by 2050 placing strains on major food crops. To sustainably feed future populations and reduce the environmental damage of intensive agriculture, crop yields must be improved without increasing the amount of cultivatable land. In this review, Simkin…

Photosynthesis is one of the most vital and complex processes carried out by plants. During photosynthesis, Photosystem I and II (PSI and PSII) undergo photo-excitation. Excessive photo-excitation can damage and deactivate the PSI by generating reactive oxygen species (ROS). This kind of photoinhibition…

Cyanobacterial carbon-dioxide concentrating mechanisms elevate intracellular inorganic carbon as bicarbonate, and then concentrate it as carbon-dioxide around the enzyme Rubisco in specialized protein micro-compartments called carboxysomes. The formation of B-carboxysomes involves an aggregation between…

Rubisco uses CO2 from the air to carboxylate its substrate RuBP, resulting in an increase in fixed carbon.  However, rubisco can also oxygenate RuBP and this leads to the production of glycolate. Plants must invest energy in recycling this toxic by-product in a process called photorespiration, resulting…

Despite its essential role in photosynthetic carbon fixation, ribulose 1,5 bisphosphate carboxylase/oxygenase (Rubisco) is a relatively inefficient enzyme, due in part to its inability to discriminate between CO2 and O2 as substrates. To suppress the oxygenase reaction and enhance the carboxylase activity…

Installation of C4 photosynthesis into C3 crops appears a realistic way to boost crop yields.  A key aspect of C4 photosynthesis is an enlarged bundle sheath volume and an increase in bundle sheath chloroplast number.  To identify the regulators of this phenotype, Döring et al. subjected Arabidopsis…

Background: Chloroplasts are the major powerhouse of plant and algal cells, where photosynthesis—the conversion of carbon dioxide into organic compounds using sunlight energy—occurs. Chloroplasts are also where important cell components (such as membrane lipids and pigments) and energy-rich compounds…

The rubisco holoenzyme is comprised of eight large subunits and eight small subunits (L8S8).  Several auxiliary proteins are required to correctly assemble the functional protein. In this manuscript, Conlan et al investigate the chaperone function of one of these proteins, BSD2, in tobacco. The authors…

It has long been thought that C4 species generally perform less well than C3 species in cold environments as a consequence of a physical space restriction.  C3 species tend to accumulate more rubisco under chilling stress to avoid limiting photosynthesis, but there is less capacity for this in C4 species…

The cyanobacterial CO2 concentrating mechanism (CCM) is dependent on a continuous supply of inorganic carbon (Ci) to rubisco inside carboxysomes in order to function optimally.  CO2 uptake pathways are therefore of great importance for a full understanding of the cyanobacterial CCM.  Sun et al demonstrate…

Introduction of the cyanobacterial carboxysome into C3 crops represents a viable strategy to increase photosynthetic conversion efficiency and boost crop yield.  Key to this challenge is gaining a full understanding of the carboxysome system in cyanobacteria, including how these microcompartments assemble…

Stomata represent the entry point into the leaf for CO2 that will be fixed by rubisco in photosynthesis and the exit point of water as it is lost to the atmosphere.  As such, they are subject to tight regulation in response to the environment so that water loss is minimised and a supply of CO2 is…

The speed at which photosynthesis is induced during shade-sun transitions, such as sun-flecks, contributes towards determining crop yield.  The speed of induction can be limited by the dynamics of stomatal and mesophyll conductance, deactivation rates of photoprotective mechanisms, the acclimation rate…

Modern crop production is intimately linked to the availability of nitrogen.  Photosynthetic proteins (including rubisco) account for most of the nitrogen in leaves, a significant amount of which is removed during harvesting and must be replenished primarily through the application of synthetic nitrogen…

It has been over seventy years since Melvin Calvin and Andrew Benson first started on their journey to discovering the Calvin-Benson cycle – the series of biochemical reactions in which the Sun’s energy is converted to chemical energy stored inside the cells of plants, cyanobacteria and algae. …

Carboxysomes are protein-bound microcompartments of cyanobacteria that sequester Rubisco and carbonic anhydrase (which converts bicarbonate to carbon dioxide), thus enhancing Rubisco’s carboxylation efficiency. The carboxysome shell is made up of hexamer, pentamer and trimer modules, with selectively…

One of the fundamental challenges facing terrestrial plants occurs when CO2 levels are depleted at Rubisco, causing its inefficient oxygenase activity to dominate. Some plants minimize this problem by adding a carbon-fixing step upstream of Rubisco, and various algae and cyanobacteria sequester Rubisco…

Senescence in plants is a prelude to cell or organ death. The metabolites and macromolecules released during senescence are salvaged by the plant for use elsewhere. Generally, senescence occurs prior to programmed cell death (PCD), since the characteristic leaf yellowing can be reversed while PCD is…

How chloroplasts remain viable inside of herbivorous sea slugs is a long-standing curiosity. Unlike corals, which host intact photosynthetic algae, sea slugs retain naked chloroplasts (which are then called kleptoplasts – stolen plastids), some of which remain viable for seveal weeks. Christa et al.…

Plants and cars need energy and are powered by a process that has changed depending on the environment: photosynthesis, in the case of plants and an engine in the case of cars. Hartzell and coworkers make an analogy in the evolution of the original C3 pathway and the evolution of the internal combustion…

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…

C4 photosynthesis relies on the transport of carbon (in the form of C4 acids) from the mesophyll into bundle sheath cells (BSCs).  Subsequent decarboxylation of these C4 acids generates a high concentration of CO2 in the vicinity of Rubisco, helping to improve the catalytic efficiency of this enzyme. …

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…

Photosynthesis is a complex process that has the potential to be greatly improved through human modifications. However, these modifications have been limited by two main factors: the high degree of conservation of the components, and the multiprotein complexes that require specifically modified proteins…

In dark-grown plants, the plastids of cotyledon cells develop as etioplasts. Etioplasts contain unique internal lattice membrane structures called prolamellar bodies (PLBs) and lamellar prothylakoids (PTs). PLBs accumulate protochlorophyllide (Pchlide), a chlorophyll intermediate, in a complex with NADPH…

Koskela and Brünje et al. identified a chloroplast protein acetyltransferase, which is required for the regulation of light harvesting in Arabidopsis. Plant Cell (2018) https://doi.org/10.1105/tpc.18.00155. by Minna M. Koskela, Annika Brünje, Iris Finkemeier, Paula Mulo   Background: Plants…

9:07:18 | Editor: Marc Platthaus From Neue Erkenntnis zur Fotosynthese entdeckt Translated by Google. The conversion of carbon dioxide and sunlight into energy (or biomass) and oxygen: hardly any process is as crucial to life on earth as photosynthesis. Although the process has been studied extensively…

Zhang et al. discover a protein that interacts with the photoreceptor phyA and plays a role in plant response to far-red light. Plant Cell https://doi.org/10.1105/tpc.17.00677  By Shaoman Zhang, Cong Li and Jigang Li Background:  Far-red (FR) light, corresponding to 700- to 750- nm wavelengths…

During seedling greening, chloroplasts are formed from proplastids. Liang and Zhu et al. used a combination of 3D electron tomography of cryo-fixed Arabidopsis cotyledons at various times after illumination to track their development. The fine structure images, accompanied by transcriptomic analysis…

Plants have many proteins found in the light-harvesting complex, whereas cyanobacteria have only the high-light-inducible proteins (Hlips).  One-helix proteins (OHPs) are the plant homologs of Hlips, but their precise functions have been unclear. Hey and Grimm used genetic and biochemical approaches…

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…

Plant scientists are familiar with the steep drop in photosynthetic activity when plants are illuminated with far-red photons (> 700 nm), because the energy of these long-wavelength photos is insufficient to initiate photochemistry at the chlorophyll a reaction center. Previously, some studies have…

The year 2016 marked a half-century since the discovery of C4 photosynthesis, yet we still seek to elucidate many of the mechanisms underpinning the C4 cycle. Although C4 and C3 plants share molecular units involved in photosynthesis (Miyao, 2003; Kellogg, 2013), C4 plants have unique morphological traits…

Green plants use photosynthesis to covert light into ATP (adenosine triphosphate) through the molecular action of the chloroplast F1Fo ATP synthase (cF1Fo). The ATP synthesis happens in the hydrophilic head (c F1) and is powered by the cFo rotary motor located in the photosynthetic membrane. This rotary…

Oxygen (O2) is evolved during photosynthetic electron transport when water is split by the oxygen-evolving complex to provide protons and electrons to the chloroplastic electron chain, thereby generating ATP and NADPH—the energy source and reducing power for plant metabolism. The majority of this chemical…

Elevated CO2 (eCO2) encourages plant growth through increased photosynthetic rates and lower stomatal conductance.  However, eCO2 also has knock-on effects on plant secondary metabolism, which can also affect plant growth.  In this review, Gamage et al explore these ‘post-photosynthetic’ effects…

In contrast to the much-studied photosynthetic processes in C4 plant vasculature, the processes in the cells surrounding C3 veins remain much less understood.  Here, there appears to be a partial and more spatially-separated C4 pathway, which has been observed in several species including rice, Arabidopsis,…

The light reactions of photosynthesis are under constant regulation in order to continue operating efficiently and avoid photodamage in a fluctuating light environment.  One mechanism to avoid photodamage is the dissipation of excess excitation energy as heat, which can be determined by measuring non-photochemical…

It is widely accepted that the growth of C3 plants responds more to elevated CO2 (eCO2) than that of C4 plants, since photosynthesis in C3 plants is more limited by the current atmospheric CO2:O2 ratio due to the oxygenase activity of Rubisco.  This has been established empirically in short-term eCO2…

While C4 photosynthesis is relatively well understood, the research community is still some distance from converting a C3 crop to one that performs C4 photosynthesis.  There are many reasons for this, including the complex requirement to reconstitute Kranz leaf anatomy in a C3 species, and the elusive…

Increasing carbon fixation through the Calvin-Benson-Bassham (CBB) cycle is a viable strategy to boost crop yields, as has been demonstrated through both experimental and modelling approaches.  In this review, Andralojc et al outline the most recent advancements in this research field.  The authors…

Plant growth is often limited by the availability of nitrogen (N), which is required to synthesise monomers and macromolecules, and is especially important in the synthesis of the carbon assimilating enzymes of the Calvin-Benson-Bassham (CBB) cycle.  In this article, Kelly has demonstrated that photosynthetic…

A major factor in determining photosynthetic rate is the availability of CO2 at the site of fixation in the chloroplast stroma.  Classically, this has been thought to be mainly limited by stomatal conductance (diffusion from the air, through stomata, to sub-stomatal cavities).  However, more recently…

Mesophyll CO2 conductance (gm) is an important factor in determining the concentration of CO2 at the site of fixation in the chloroplast stroma, and as such is crucial for determining photosynthetic capacity.  The mesophyll cell wall provides a major site of resistance to CO2 diffusion into the stroma…

It is relatively simple to determine net O2 flux in leaves.  However, this data provides no information on the underlying processes responsible for this flux, namely gross oxygen production (GOP, water splitting), mitochondrial respiration in light, Rubisco oxygenation, and photorespiration.  In this…

Phosphorus (P) is an essential macronutrient, and P deficiency limits plant productivity. P influences many aspects of photosynthesis P-deficient plants typically remain green and do not develop leaf chlorosis and yet P starvation immediately affects CO2 assimilation. Specifically, P deficiency is believed…

The carbon-fixing enzyme Rubisco (Ribulose‐1,5‐bisphosphate carboxylase/oxygenase) is much-maligned and has been described as “sluggish” and with “confused specificity”. In this new Review, Bathellier et al. argue that it is “not really so bad”. Their reasoning is that when Rubisco’s…

Following up on earlier studies in which they introduced cyanobacterial Rubisco into tobacco, Lin and Hanson endeavoured to introduce into tobacco Rubisco genes from a red alga, which has an unusually high CO2/O2 specificity. Although they were able to demonstrate the presence of the genes and their…

Phosphorus deficiency is widespread and can severely limit plant growth.  Carstensen et al. investigated how P deficiency affects photosynthesis in barley. They compared chlorophyll a fluorescence transients (OJIP transients) between P-deficient, sufficient and resupplied plants. They observed depletion…

Du et al. investigate an important protein that regulates photosynthesis under stress. Plant Cell. https://doi.org/10.1105/tpc.17.00446.                                                                               Background:…

By Johan Ceuster and Bram Van de Poel Abstract The volatile plant hormone ethylene plays a regulatory role in many developmental processes and in biotic and abiotic stress responses. One of the under-explored actions of ethylene is its regulation of photosynthesis and associated components such…

Although the reactions and enzymes involved in the biosynthesis of chlorophyll are well known, the entire pathway has never before been reconstituted in a non-photosynthetic organism. Chen et al. have done this. The cells (E. coli) expressing the full pathway accumulate chlorophyll and look green! However,…

Malnoë et al. demonstrate that a protein from the lipocalin family plays a role in promoting energy dissipation that prevents damage from long-term light stress. The Plant Cell (2017).  https://doi.org/10.1105/tpc.17.00536  By Alizée Malnoë Background: Light is necessary for plant growth…

Dinoflagellates in the genus Symbiodinium have the ability to enter into endosymbiotic associations with corals, providing the metabolic basis for the highly productive and biologically diverse coral-reef ecosystems, as well as with other cnidarians, including sea anemones and jellyfish. The Symbiodinium-coral…

Mineral deposits occur in many, but not all plant leaves. In those leaves that do have minerals, the mineral type, morphology and the distributions within the leaves are under strict control. In fact, mineralization in certain leaves is a well-preserved trait throughout evolution, indicating that such…

Phytochromes are plant photoreceptors that can sense red and far-red light, as-well-as the ratio of these light qualities.  This review examines the relationship between phytochrome signalling and carbon metabolism.  Krahmer et al. assess the influence of phytochrome signalling on the synthesis of…

Plants have several mechanisms to protect themselves from damage from excess light, including a set of reactions collectively described as non-photochemical quenching or NPQ. One of these is a sustained and slowly reversible form of NPQ, which the authors have named qH. How this sustained NPQ functions…

Increasing photosynthetic conversion efficiency is an attractive target for improving crop yields.  One way of affecting this is to alter the way CO2 is delivered to Rubisco, the carbon-fixing enzyme of photosynthesis.  Lehmeier et al. aimed to change the pattern of air spaces within Arabidopsis leaves…

In plants, Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo), the enzyme responsible for fixing carbon, is a made up of 8 each of the large and small subunits, making the L8S8 form. Efforts to study this enzyme have been thwarted by the inability to assemble an active L8S8 form in a heterologous…

During photosynthesis Rubisco fixes CO2 by carboxylating its substrate RuBP, leading to the de novo production of carbohydrates.  Photorespiration has long been considered a wasteful process, initiated by Rubisco-mediated oxygenation of RuBP and resulting in the loss of carbon, nitrogen and energy. …

The coordinated differentiation of cell types during the metamorphosis of an organ is crucial for ensuring that the final form of the organ is appropriate for itsfunction.  A case in point is the photosynthetic function of plant leaves that requires chloroplast-containing cells in the middle leaf layers…

Understanding the metabolic pathways underlying oil production and the precise intracellular localization of lipid droplets is crucial for successfully engineering microalgae for biofuel production. The microalga Chlamydomonas reinhardtii accumulates considerable amounts of starch and triacylglycerol…

Increased leaf vein density is considered to be a key early step in the evolution of C4 photosynthesis.  Feldman et al. analyzed five mutants with high vein densities in the C3 crop rice to determine if photosynthetic assimilation was improved.  The mutants all had higher photosynthetic rates under…

Light intensity varies seasonally, with time of day, with cloudiness, and as overlying leaves move in the wind.  A sudden change in light intensity alters photosynthetic responses, but not all responses change at the same rate. For example, upon an increase in light intensity, photosynthetic electron…

By Rebecca A Slattery, Berkley J Walker, Andreas P.M. Weber, Donald R. Ort Abstract Rapidly changing light conditions can reduce carbon gain and productivity in field crops because photosynthetic responses to light fluctuations are not instantaneous. Plant responses to fluctuating light occur across…

MicroRNAs (miRNAs), a class of abundant small noncoding RNAs, have been identified as important regulators of gene expression in plants, affecting many aspects of plant development. Recently, several miRNAs have been reported to regulate rice grain yield. A previous study revealed that miR397 regulates…

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…

SHORTROOT (SRT) is a transcription factor that contributes to developmental patterning non-cell autonomously, by moving between cells. In leaves, SRT has been shown to contribute to sub-epidermal patterning specified by distance from the vein. Schuler et al. explored whether it also contributes to epidermal…

The effect of reducing leaf chlorophyll content on canopy CO2 assimilation (Acan) is somewhat contentious.  Walker et al. obtained data from 67 soybean accessions to parameterise a canopy-root-soil model (MLCan) in order to simulate the effect of altering chlorophyll levels on Acan.  There was no increase…

Chlorophyll fluorescence is a common tool to investigate the behavior of the photosynthetic appratus, therefore photosynthetic capacity, at any physiological state. However, the different optical density of the samples can lead to light-dependent over- or underestimation of effective PSII quantum yields.…

The C4 Rice project aims to transition rice from a C3 crop to one that performs C4 photosynthesis, in order to realize a predicted 50% increase in yield.  Here, Wang et al. expressed a positive regulator of chloroplast development, the maize GOLDEN2-LIKE transcription factor, in rice.  The resulting…

Boxall et al. investigate CAM photosynthesis in Kalanchoë fedtschenkoi The Plant Cell (2017). https://doi.org/10.1105/tpc.17.00301 Background: During photosynthesis, most plants use the enzyme Rubisco to capture CO2 during the day. Crassulacean acid metabolism (CAM) plants such as prickly pears,…

By Elias Kaiser, Alejandro Morales, Jeremy Harbinson The environment of the natural world in which plants live, have evolved, and within which photosynthesis operates, is one characterised by change. The time scales over which change occurs can range from seconds (or less) all the way to the geological…

One of the great questions of biology is how and why C4 photosynthesis pathway evolved independently more than 60 times. The advantages are obvious (increased productivity), but the underlying molecular predisposition to this transition remains poorly defined. Using a comparative transcriptomics approach…

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…

Due to its ease of use and noninvasive nature, variable chlorophyll fluorescence techniques have become increasingly popular for estimating photosynthetic parameters. Most measurements of variable chlorophyll fluorescence in complex plant tissues and surface-associated cell assemblages (e.g. biofilms)…

Photosynthesis in aquatic organisms is made difficult due to the low solubility of CO2 in water. Algae such as Chlamydomonas rheinhardtii overcome this limitation through a carbon-concentrating organelle called a pyrenoid. Two papers in Cell redefine our understanding of the pyrenoid structure. Mackinder…

Boosting photosynthetic efficiency in crop species has long been a goal since efficiency of photosynthesis is a critical factor in crop yield. One strategy for improving photosynthetic rates is enhancing mesophyll conductance to carbon dioxide. Tomeo and  Rosenthal examined 12 cultivars of soybean (Glycine…

MacGregor-Chatwin et al. map the cellular organization of photosynthetic protein complexes http://www.plantcell.org/content/29/5/1119 Life on Earth depends on photosynthesis, the source of all of our food, oxygen, and most of our energy. Two pigment-protein complexes called Photosystems I and II…