Entries by Patrice Salome

The Shape of Rings to Come: Systems Approach to Xylem and Phloem Formation in Arabidopsis

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 nudge freshly divided cells toward phloem xylem or procambium cell […]

Developmental timing is everything (part II): gating of high temperature responses by the circadian clock

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 study responses to elevated temperatures do not always adhere to a standard protocol and can vary […]

In the Pale Red Light: Control of pre-mRNA Splicing by RRC1 and SFPS

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 avalanche of genetic screens has fleshed out phy signaling cascade over […]

Barreling down the Chloroplast Highway: Protein Sorting of Outer-Membrane β-Barrel Proteins

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 nightmare: how do proteins, translated in the cytosol by the host ribosomes […]

Mediator Skills: MED16 Controls Endoreduplication

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 factor titrates components (i.e., Mediator) critical for the proper initiation of […]

Too Close to the Flame: Duplicated ICARUS Genes and Growth at Higher Temperatures

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 stop growing. Such was the premise that led to the cloning of […]

Plants on (Brassinos)steroids: Degradation of the Transcription Factor BZR1 by the E3 Ubiquitin Ligase PUB40

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 (Levin and Hammes, 2016). Our understanding of BR signaling in Arabidopsis thaliana […]

The shade of things to come: plastid retrograde signaling and shade avoidance

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 hypocotyl elongation and returning the plant to […]