Jasmonate signaling controls negative and positive effectors of salt stress tolerance in rice

Jasmonate dually impacts osmotic and ionic components of salt stress in rice. Jasmonate is required for abscisic acid-mediated water deprivation responses, but inhibits Na(+)retention in roots, promoting leaf damage. Plant responses to salt exposure involve large reconfigurations of hormonal pathways that orchestrate physiological changes towards tolerance. Jasmonate (JA) hormones are essential to withstand biotic and abiotic assaults, but their roles in salt tolerance remain unclear. Here we describe the dynamics of JA metabolism and signaling in root and leaf tissue of rice, a plant species that is highly exposed and sensitive to salt. Roots activate the JA pathway in an early pulse, while the second leaf displays a biphasic JA response with peaks at 1 h and 3 d post-exposure. Based on higher salt tolerance of a rice JA-deficient mutant (aoc), we examined, through kinetic transcriptome and physiological analysis, the salt-triggered processes that are under JA control. Profound genotype-differential features emerged that could underlie the observed phenotypes. Abscisic acid (ABA) content and ABA-dependent water deprivation responses were impaired in aoc shoots. Moreover, aoc accumulated more Na+ in roots, and less in leaves, with reduced ion translocation correlating with root derepression of the HAK4 Na+ transporter gene. Distinct reactive oxygen species scavengers were also stronger in aoc leaves, along with reduced senescence and chlorophyll catabolism markers. Collectively, our results identify contrasted contributions of JA signaling to different sectors of the salt stress response in rice.

Automated summary

Jasmonate has dual impacts on the osmotic and ionic components of salt stress in rice. It is required for abscisic acid-mediated water deprivation responses but inhibits Na(+) retention in roots, leading to leaf damage. This study investigates the dynamics of JA metabolism and signaling in rice and identifies contrasted contributions of JA signaling to different sectors of the salt stress response in the plant.