Active photosynthetic inhibition mediated by MPK3/MPK6 is critical to effector-triggered immunity

作者：Su, Jianbin; Yang, Liuyi; Zhu, Qiankun; Wu, Hongjiao; He, Yi; Liu, Yidong; Xu, Juan; Jiang, Dean; Zhang, Shuqun^*

来源：PLOS BIOLOGY, 2018, 16(5): e2004122.

DOI：10.1371/journal.pbio.2004122

• PATTERN-RECOGNITION RECEPTORS
• PLANT-PATHOGEN INTERACTIONS
• GROWTH-DEFENSE TRADEOFFS
• DISEASE-RESISTANCE GENES
• TOBACCO-MOSAIC-VIRUS
• PHOTOSYSTEM-II
• PSEUDOMONAS-SYRINGAE
• CELL-DEATH
• CHLOROPHYLL FLUORESCENCE
• ARABIDOPSIS-THALIANA

Extensive research revealed tremendous details about how plants sense pathogen effectors during effector-triggered immunity (ETI). However, less is known about downstream signaling events. In this report, we demonstrate that prolonged activation of MPK3 and MPK6, two Arabidopsis pathogen-responsive mitogen-activated protein kinases (MPKs), is essential to ETI mediated by both coiled coil-nucleotide binding site-leucine rich repeats (CNLs) and toll/interleukin-1 receptor nucleotide binding site-leucine rich repeats (TNLs) types of R proteins. MPK3/MPK6 activation rapidly alters the expression of photosynthesisrelated genes and inhibits photosynthesis, which promotes the accumulation of superoxide (O-2(.-)) and hydrogen peroxide (H2O2), two major reactive oxygen species (ROS), in chloroplasts under light. In the chemical-genetically rescued mpk3 mpk6 double mutants, ETI-induced photosynthetic inhibition and chloroplastic ROS accumulation are compromised, which correlates with delayed hypersensitive response (HR) cell death and compromised resistance. Furthermore, protection of chloroplasts by expressing a plastid-targeted cyanobacterial flavodoxin (pFLD) delays photosynthetic inhibition and compromises ETI. Collectively, this study highlights a critical role of MPK3/MPK6 in manipulating plant photosynthetic activities to promote ROS accumulation in chloroplasts and HR cell death, which contributes to the robustness of ETI. Furthermore, the dual functionality of MPK3/MPK6 cascade in promoting defense and inhibiting photosynthesis potentially allow it to orchestrate the trade-off between plant growth and defense in plant immunity.

• 出版日期2018-5
• 单位浙江大学