Spatial regulation of RBOHD via AtECA4‐mediated recycling and clathrin‐mediated endocytosis contributes to ROS accumulation during salt stress response but not flg22‐induced immune response

Abstract

SUMMARY Various environmental stresses can induce production of reactive oxygen species (ROS) to turn on signaling for proper responses to those stresses. Plasma membrane (PM)‐localized respiratory burst oxidase homologs (RBOHs), in particular RBOHD, produce ROS via the post‐translational activation upon abiotic and biotic stresses. Although the mechanisms of RBOHD activation upon biotic stress have been elucidated in detail, it remains elusive how salinity stress activates RBOHD. Here, we present evidence that trafficking of PM‐localized RBOHD to endosomes and then its recycling back to the PM is critical for ROS accumulation upon salinity stress. ateca4 plants that were defective in recycling of proteins from endosomes to the PM and clc2‐1 and chc2‐1 plants that were defective in endocytosis showed a defect in salinity stress‐induced ROS production. In addition, ateca4 plants showed a defect in transient accumulation of GFP:RBOHD to the PM at the early stage of salinity stress. By contrast, ateca4 plants showed no defect in the increase in the ROS level and accumulation of RBOHD to the PM upon flg22 treatment as wild‐type plants. Based on these observations, we propose that factors involved in the trafficking machinery such as AtECA4 and clathrin are important players in salt stress‐induced, but not flg22‐induced, ROS accumulation.

SEC14-GOLD protein PATELLIN2 binds IRON-REGULATED TRANSPORTER1 linking root iron uptake to vitamin E

“…This is interesting because these extracellular vesicles contained ROS-related functions, including APX1 and GST (GLUTATHIONE S-TRANSFERASE PHI2 [AT4G02520]) ( Rutter and Innes, 2017 ), coinciding with the two PATL2 interactome-enriched GO categories ROS responses and endomembrane trafficking. In plants, ROS signaling via NADPH oxidase respiratory burst oxidase homolog (RBOH) proteins is connected with clathrin-mediated endocytosis ( Lee et al, 2021 ), also dependent on extracellular Fe 2+ ( Martinière et al, 2019 ). The identified PATL2-interacting TRX3 possibly links redox functions to membrane-related processes.…”

Membrane trafficking functions of the ANTH/ENTH/VHS domain‐containing proteins in plants

“…A subpopulation of PICALM4a/ECA4 is localized at the TGN, in addition to the PM and forming cell plate [50,51]. The picalm4a/eca4 single mutant exhibits higher resistance to osmotic stress and elevated sensitivity to exogenous ABA than the wild-type, which could have resulted from the altered intracellular trafficking of PM proteins, such as ABCG25 and the PM-localized NADPH oxidase RBOHD [50,52]. Intriguingly, the pi-calm4a/eca4 mutation confers distinct effects on ROS production mediated by RBOHD between the salinity stress response and flg22-induced immune response [52], the mechanism of which should be investigated in future studies.…”

Evolutionary Analysis of Respiratory Burst Oxidase Homolog (RBOH) Genes in Plants and Characterization of ZmRBOHs

“…Ten RBOHs have been found in Arabidopsis and named AtRbohA–J [ 7 ], and nine RBOHs in rice [ 13 ], fourteen in Nicotiana tabacum [ 14 ], seventeen in soybean [ 10 ], forty-six in wheat [ 15 ], fourteen in Brassica rapa [ 16 ], and seven in grapes [ 17 ]. RBOHs are regarded as the center hubs in the ROS signaling network and play an essential role in stress responses and plant development [ 18 , 19 , 20 ]. It has been reported that RBOHs have a vital role in pollen development [ 21 ], pollen tube growth [ 22 ], root hair development [ 23 ], seed germination [ 24 ], plant-microorganism interactions [ 25 ] and plant immunity [ 26 ].…”