The study introduced charge-altering mutations into the N‑terminal region of Lhcb2 in Arabidopsis thaliana lacking native Lhcb2 to assess how intrinsic charge affects LHCII phosphorylation, state‑transition efficiency, and PSI‑LHCII complex formation. The R2E mutation drastically reduced Lhcb1/2 phosphorylation, impaired state transitions, and prevented PSI‑LHCII assembly, whereas the Q9E mutation had no measurable impact, and neither mutation altered thylakoid ultrastructure. Residual state transitions in the R2E line suggest that other Stn7 substrates can partially compensate for the loss of Lhcb2 phosphorylation.
The authors used a bottom‑up thermodynamic modelling framework to investigate how plants decode calcium signals, starting from Ca2+ binding to EF‑hand proteins and extending to higher‑order decoding modules. They identified six universal Ca2+-decoding modules that can explain variations in calcium sensitivity among kinases and provide a theoretical basis for interpreting calcium signal amplitude and frequency in plant cells.
The study examines how ectopic accumulation of methionine in Arabidopsis thaliana leaves, driven by a deregulated AtCGS transgene under a seed‑specific promoter, reshapes metabolism, gene expression, and DNA methylation. High‑methionine lines exhibit increased amino acids and sugars, activation of stress‑hormone pathways, and reduced expression of DNA methyltransferases, while low‑methionine lines show heightened non‑CG methylation without major transcriptional changes. Integrated transcriptomic and methylomic analyses reveal a feedback loop linking sulfur‑carbon metabolism, stress adaptation, and epigenetic regulation.
The study reveals that brassinosteroids activate phosphoenolpyruvate carboxykinase (PCK) by promoting dephosphorylation of conserved Ser-62 and Thr-66 residues, a process antagonized by the GSK3-like kinase BIN2. BR‑deficient Arabidopsis mutants exhibit reduced PCK activity, while phospho‑blocking mutations confer BR‑independent activation and enhanced seedling growth, and similar regulatory mechanisms are observed in maize and sorghum leaves.
The study generated deep proteome and phosphoproteome datasets from guard cell‑enriched tissue to examine how phosphorylation regulates stomatal movements. Comparative analysis revealed increased phosphorylation of endomembrane trafficking and vacuolar proteins in closed stomata, supporting a role for phospho‑regulated trafficking in stomatal dynamics.
EPP1 is an ancestral component of the plant Common SymbiosisPathway
Authors: Rich, M. K., Vernie, T., Tiwari, M., Chauderon, L., Causse, J., Pellen, T., Boussaroque, A., Bianconi, M. E., Vandenbussche, M., Chambrier, P., Le Ru, A., Castel, B., Nagalla, S., Cullimore, J., Keller, J., Valdes-Lopez, O., Mbengue, M., Ane, J.-M., Delaux, P.-M.
The study identifies EPP1 as a fourth, conserved component of the ancestral common symbiosis pathway required for intracellular plant–microbe interactions, showing that its loss impairs arbuscular mycorrhizal colonization across diverse plant clades. EPP1 is phosphorylated by the plasma‑membrane receptor SYRMK, and this modification is essential for downstream activation of the nuclear kinase CCaMK, positioning EPP1 upstream in the signaling cascade.
Brassinosteroid treatment reveals the importance of xyloglucan transglucosylase/hydrolase (XTH) genes in growth habit determination of twining common bean vines
Authors: Hunt, L. M., Sousa-Baena, M. S., Acevedo, A. A., Semana, L., Wang, A., Glos, R. A. E., Ambrose, B., Anderson, C. T., Onyenedum, J. G.
The study investigated how brassinosteroids and their inhibitor affect G-fiber development and the twining habit in common bean by applying hormones, then analyzing anatomical, biochemical, and transcriptomic changes. Brassinosteroid treatment produced elongated internodes with thin-walled G‑fibers, while inhibition yielded short internodes with thick G‑fibers, both linked to differential expression of XTH genes and xyloglucan remodeling in the G‑layer.
The study demonstrates that ABI5‑Binding Proteins (AFPs) interact with multiple components of the core ABA signaling pathway and serve as substrates for SnRK2 kinases and PP2C phosphatases, linking them to MAP kinases and 14‑3‑3 proteins. Phosphorylation of AFP2, promoted by ABA, stabilizes the protein and influences its subcellular localization, thereby modulating its ability to inhibit ABA responses during seed germination.
The study quantitatively measures binding kinetics of four Arabidopsis thaliana brassinosteroid receptors with fifteen BRs, identifying chemical features required for high‑affinity binding and co‑receptor recognition. Structural analysis of BR‑bound receptor ectodomains combined with extensive in vitro and in vivo mutagenesis reveals a highly plastic hormone‑binding pocket, and functional assays with structure‑based agonists and antagonists show that receptor‑co‑receptor complexes can accommodate chemically diverse BRs, adding a new regulatory layer to BR signaling.
The study identifies the RNA‑binding protein AtG3BP1 as a phosphorylation target of MAPKs MPK3, MPK4, and MPK6 at Ser257 in Arabidopsis thaliana and shows that this modification promotes susceptibility to bacterial pathogens, suppresses ROS accumulation and salicylic acid biosynthesis, and maintains stomatal opening. Phospho‑mimic and phospho‑dead mutants reveal that phosphorylation stabilizes AtG3BP1 by preventing proteasomal degradation, highlighting a novel post‑translational control layer in plant immunity.