AUTHOR=Song Ru-Feng , Li Ting-Ting , Liu Wen-Cheng 

TITLE=Jasmonic Acid Impairs Arabidopsis Seedling Salt Stress Tolerance Through MYC2-Mediated Repression of CAT2 Expression

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.730228

DOI=10.3389/fpls.2021.730228

ISSN=1664-462X

ABSTRACT=<p>High salinity causes ionic, osmotic, and oxidative stresses to plants, and the antioxidant enzyme Catalase2 (CAT2) plays a vital role in this process, while how <italic>CAT2</italic> expression is regulated during plant response to high salinity remains elusive. Here, we report that phytohormone jasmonic acid (JA) impairs plant salt stress tolerance by repressing <italic>CAT2</italic> expression in an MYC2-dependent manner. Exogenous JA application decreased plant salt stress tolerance while the <italic>jar1</italic> mutant with reduced bioactive JA-Ile accumulation showed enhanced salt stress tolerance. JA enhanced salt-induced hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) accumulation, while treatment with H<sub>2</sub>O<sub>2</sub>-scavenger glutathione compromised such effects of JA on plant H<sub>2</sub>O<sub>2</sub> accumulation and salt stress tolerance. In addition, JA repressed <italic>CAT2</italic> expression in salt-stressed wild-type plant but not in <italic>myc2</italic>, a mutant of the master transcriptional factor MYC2 in JA signaling, therefore, the <italic>myc2</italic> mutant exhibited increased salt stress tolerance. Further study showed that mutation of <italic>CAT2</italic> largely reverted lower reactive oxygen species (ROS) accumulation, higher CAT activity, and enhanced salt stress tolerance of the <italic>myc2</italic> mutant in <italic>myc2 cat2-1</italic> double mutant, revealing that <italic>CAT2</italic> functions downstream JA-MYC2 module in plant response to high salinity. Together, our study reveals that JA impairs Arabidopsis seedling salt stress tolerance through MYC2-mediated repression of <italic>CAT2</italic> expression.</p>