Genetius

The study identifies the cysteine‑rich receptor‑like kinase CRK5 as a negative regulator of salicylic‑acid‑mediated cell death and a positive regulator of antioxidant homeostasis during dark‑induced leaf senescence in Arabidopsis. Loss‑of‑function crk5 mutants display accelerated senescence, elevated ROS and electrolyte leakage, and altered antioxidant enzyme activities, phenotypes that are rescued by suppressing SA biosynthesis or catabolism. Transcriptome analysis reveals extensive deregulation of senescence‑ and redox‑related genes, highlighting CRK5’s central role in coordinating hormonal and oxidative pathways.

The study demonstrates that FERONIA and phytochrome B physically interact with the NADPH oxidase RBOHD, and that FERONIA-mediated phosphorylation of phyB is essential for RBOHD-driven ROS production under excess light stress in Arabidopsis thaliana. Additional membrane proteins CRK10 and PIP2;6 also associate with this complex, forming a plasma‑membrane assembly that integrates multiple signaling pathways to regulate stress‑induced ROS.

The study examined how Arabidopsis calcium‑dependent protein kinases AtCPK5 and AtCPK6 modulate immunity triggered by bacterial rhamnolipids, finding that RLs up‑regulate these kinases and that mutants, especially cpk5/6, show altered reactive oxygen species production and defense gene expression. However, these kinases did not influence RL‑induced electrolyte leakage or resistance to Pseudomonas syringae pv. tomato DC3000, indicating additional signaling components are involved.

A comparative phosphoproteomics study using Arabidopsis thaliana ahk5 loss‑of‑function mutants and wild‑type seedlings revealed that the histidine kinase AHK5 mediates a rapid shift from multistep phosphorelay signaling to serine/threonine phosphorylation in response to H2O2. AHK5 controls ROS‑responsive phosphorylation of plasma‑membrane nanodomain proteins and orchestrates distinct ABA‑independent stomatal closure and ABA‑dependent root development pathways by modulating key components such as RBOHD, CAS, HPCA1, and auxin transporters.

The study reconstitutes Papaver rhoeas self‑incompatibility in Arabidopsis thaliana by expressing the pollen S‑determinant PrpS and shows that incompatibility rapidly triggers a Ca2+ and pH‑dependent cascade leading to mitochondrial hydrogen peroxide production, membrane depolarization, reduced respiration, ATP depletion, and glycolytic inhibition via GAPDH oxidation. Early inactivation of plasma‑membrane NADPH oxidase limits superoxide generation, indicating distinct ROS sources drive separate aspects of the response before programmed cell death.

The study demonstrates that constitutively active MLO (faNTA) can rescue the fer-4 root‑hair bursting and polarity defects, restoring tip‑focused cytosolic Ca2+ oscillations and ROS accumulation, highlighting a FERONIA‑MLO signaling module that governs Ca2+ influx and ROS production during root‑hair tip growth. Genetic analysis of mlo15-4 further confirms MLO15 as a key regulator of these Ca2+ and ROS dynamics. The findings suggest MLO proteins act downstream of FER to coordinate calcium and ROS signals essential for root‑hair integrity.

The study reveals that reactive oxygen species have distinct functions during stigma papillae development in Arabidopsis thaliana, with superoxide predominating during early growth and hydrogen peroxide accumulating in mature, receptive papillae. Pharmacological reduction of superoxide or early overexpression of superoxide dismutase impairs papillae growth, indicating that ROS homeostasis is essential for proper stigma maturation and successful pollination.

The study used label-free quantitative proteomics to examine how calcium signaling influences the Arabidopsis thaliana leaf proteome during hydrogen peroxide‑induced oxidative stress, comparing responses with and without the Ca²⁺ channel blocker LaCl₃. Results showed distinct calcium‑dependent and independent protein abundance changes, with calcium signaling largely attenuating the oxidative stress response and affecting protein degradation dynamics.

The study demonstrates that the calcium‑sensor proteins CBL1 and CBL9, together with the kinase CIPK6, form a module that negatively regulates the activity of the NADPH oxidase RbohD and limits reactive oxygen species (ROS) production during Arabidopsis immunity. Phosphorylation of RbohD at Ser33 by this complex suppresses its activity, overriding the activating effect of Ser39 phosphorylation, thereby balancing the immune response against Pseudomonas syringae.

The study demonstrates that dihydroxy B‑ring flavonoids modulate the amplitude of the core circadian clock gene reporter TOC1:LUC in Arabidopsis by affecting cellular H2O2 levels, rather than auxin transport. Reducing reactive oxygen species restored normal TOC1:LUC amplitude in flavonoid‑deficient seedlings, and altered chloroplast Ca2+ levels suggest a retrograde signaling component.