植物が攻撃されるとき(When plants are attacked)

2024-02-28

2024-02-26 ミシガン大学

植物の細胞は病原体攻撃に反応し、免疫システムを活性化するための小さな分子である二次メッセンジャーを生成する。その中で、リン脂質であるPAが最初に免疫システムを活性化するが、その急激な上昇と下降の原因は不明だった。しかし、ミシガン大学の研究者らは、この急激な変化を引き起こす微小な酵素DGK5を特定し、その制御機構を解明した。DGK5は、PAの急激な上昇を引き起こす第一の酵素と、その生産を抑制する第二の酵素と相互作用することが明らかになった。

<関連情報>

DGK5を介したPAバーストの二重リン酸化が植物免疫における活性酸素を制御する Dual phosphorylation of DGK5-mediated PA burst regulates ROS in plant immunity

Liang Kong,Xiyu Ma,Chao Zhang,…,Teun Munnik,Ping He,Libo Shan
Cell Published:January 19, 2024
DOI:https://doi.org/10.1016/j.cell.2023.12.030

Highlights

•Immune elicitation triggers two distinct phosphorylation patterns of DGK5

•BIK1- and MPK4-mediated DGK5 phosphorylation opposingly regulates PA burst

•PA binds and stabilizes the NADPH oxidase RBOHD in regulating ROS production

•DGK5 is involved in plant PRR- and NLR-mediated immunity

Summary

Phosphatidic acid (PA) and reactive oxygen species (ROS) are crucial cellular messengers mediating diverse signaling processes in metazoans and plants. How PA homeostasis is tightly regulated and intertwined with ROS signaling upon immune elicitation remains elusive. We report here that Arabidopsis diacylglycerol kinase 5 (DGK5) regulates plant pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). The pattern recognition receptor (PRR)-associated kinase BIK1 phosphorylates DGK5 at Ser-506, leading to a rapid PA burst and activation of plant immunity, whereas PRR-activated intracellular MPK4 phosphorylates DGK5 at Thr-446, which subsequently suppresses DGK5 activity and PA production, resulting in attenuated plant immunity. PA binds and stabilizes the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD), regulating ROS production in plant PTI and ETI, and their potentiation. Our data indicate that distinct phosphorylation of DGK5 by PRR-activated BIK1 and MPK4 balances the homeostasis of cellular PA burst that regulates ROS generation in coordinating two branches of plant immunity.