A genome-wide survey identified 217 EXO70 genes across five kiwifruit (Actinidia spp.) species, classifying them into three subfamilies and nine clades and revealing lineage‑specific expansions, especially in EXO70C, EXO70E, and EXO70H. Functional assays demonstrated that kiwifruit EXO70B1 interacts with the immune hub protein RIN4_1, suggesting a conserved EXO70‑RIN4 module in plant immunity. The study provides a foundational resource for exploring EXO70‑mediated disease resistance in kiwifruit.
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.
Using a microfluidic valve rootchip, the study simultaneously tracked ROS and calcium dynamics in compressed roots and found three kinetic phases linking mechanosensitive channel activity, NADPH oxidase‑dependent ROS accumulation, and secondary calcium influx. Pharmacological inhibition revealed that a fast calcium response is mediated by plasma‑membrane mechanosensitive channels, while a slower calcium increase is driven by ROS production.
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.
Uncovering the Molecular Regulation of Seed Development and Germination in Endangered Legume Paubrasilia echinata Through Proteomic and Polyamine Analyses
Authors: Vettorazzi, R. G., Carrari-Santos, R., Sousa, K. R., Oliveira, T. R., Grativol, C., Olimpio, G., Venancio, T. M., Pinto, V. B., Quintanilha-Peixoto, G., Silveira, V., Santa-Catarna, C.
The study examined seed maturation and germination in the endangered legume Paubrasilia echinata using proteomic and polyamine analyses at 4, 6, and 8 weeks post-anthesis, identifying over 2,000 proteins and linking specific polyamines to developmental stages. Mature seeds (6 weeks) showed elevated proteasome components, translation machinery, LEA proteins, and heat shock proteins, while polyamine dynamics revealed putrescine dominance in early development and spermidine/spermine association with desiccation tolerance and germination. These findings uncover dynamic molecular shifts underlying seed development and provide insights for conservation and propagation.
Phosphoproteomics uncovers rapid and specific transition from plant two-component system signaling to Ser/Thr phosphorylation by the intracellular redox sensor AHK5
Authors: Drechsler, T., Li, Z., Schulze, W. X., Harter, K. J. W.
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 reveals that the energy sensor SnRK1 modulates Arabidopsis defense by repressing SA‑dependent gene expression and bacterial resistance, with its activity enhanced under high humidity. SnRK1 interacts with TGA transcription factors to attenuate PR1 expression, linking cellular energy status to immune regulation.
The study characterizes the single-copy S-nitrosoglutathione reductase 1 (MpGSNOR1) in the liverwort Marchantia polymorpha, showing that loss-of-function mutants generated via CRISPR/Cas9 exhibit marked morphological defects and compromised SNO homeostasis and immune responses. These findings indicate that GSNOR-mediated regulation of S‑nitrosylation is an ancient mechanism linking development and immunity in early land plants.
The study provides a comprehensive proteomic analysis of seed mitochondria from white lupin, revealing fully assembled OXPHOS complexes ready for immediate energy production upon imbibition. Quantitative mass‑spectrometry identified 1,162 mitochondrial proteins, highlighting tissue‑specific transporter and dehydrogenase profiles and dynamic remodeling during early germination, while many uncharacterized proteins suggest novel legume‑specific functions.
Light on its feet: Acclimation to high and low diurnal light is flexible in Chlamydomonas reinhardtii
Authors: Dupuis, S., Chastain, J. L., Han, G., Zhong, V., Gallaher, S. D., Nicora, C. D., Purvine, S. O., Lipton, M. S., Niyogi, K. K., Iwai, M., Merchant, S. S.
The study examined how prior light‑acclimation influences the fitness and rapid photoprotective reprogramming of Chlamydomonas during transitions between low and high diurnal light intensities. While high‑light‑acclimated cells struggled to grow and complete the cell cycle after shifting to low light, low‑light‑acclimated cells quickly remodeled thylakoid ultrastructure, enhanced photoprotective quenching, and altered photosystem protein levels, recovering chloroplast function within a single day. Transcriptomic and proteomic profiling revealed swift induction of stress‑response genes, indicating high flexibility in diurnal light acclimation.