Abstract
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 CAT2 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 CAT2 expression in an MYC2-dependent manner. Exogenous JA application decreased plant salt stress tolerance while the jar1 mutant with reduced bioactive JA-Ile accumulation showed enhanced salt stress tolerance. JA enhanced salt-induced hydrogen peroxide (H2O2) accumulation, while treatment with H2O2-scavenger glutathione compromised such effects of JA on plant H2O2 accumulation and salt stress tolerance. In addition, JA repressed CAT2 expression in salt-stressed wild-type plant but not in myc2, a mutant of the master transcriptional factor MYC2 in JA signaling, therefore, the myc2 mutant exhibited increased salt stress tolerance. Further study showed that mutation of CAT2 largely reverted lower reactive oxygen species (ROS) accumulation, higher CAT activity, and enhanced salt stress tolerance of the myc2 mutant in myc2 cat2-1 double mutant, revealing that CAT2 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 CAT2 expression.
Highlights
High concentrations of sodium (Na+) in soil severely affects crop growth, causing enormous loss of crop quantity and quality and posing serious food security worldwide (Munns and Tester, 2008; Yang and Guo, 2018; Qin et al, 2020)
Our results showed that jasmonic acid (JA) accumulation in salt-treated plants was significantly higher than that in the untreated control (Figure 1A), indicating that salt stress induces JA accumulation in plants
Our results showed that low concentration of exogenous JA alone did not but high salinity significantly affected seed germination and cotyledon greening process, and exogenous JA further enhanced the salt stress effects (Figures 1B,C), suggesting a negative regulatory role of JA in plant salt stress tolerance
Summary
High concentrations of sodium (Na+) in soil severely affects crop growth, causing enormous loss of crop quantity and quality and posing serious food security worldwide (Munns and Tester, 2008; Yang and Guo, 2018; Qin et al, 2020). Plants usually cannot avoid high salinity-induced damages by directly changing their location due to the sessile lifestyle. Plants have evolved sophisticated and complex mechanisms to respond to excess Na+ in the soil to survive and reproduce themselves (Munns and Tester, 2008). High salinity reduces plant water uptake and disturbs plant normal physiological processes, causing osmotic and ionic stress. In addition to ionic and osmotic stresses caused by salt stress, high salinity elicits oxidative stress, a secondary effect, resulted from salt-induced
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
