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

International audiencePlant responses to salt exposure involve large reconfiguration 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 of rice, a plant species that is highly exposed and sensitive to salt. Roots activate the JA pathway in an early pulse, while 2nd leaf displays a biphasic JA response with peaks at 1 hour and 3 days 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 observed phenotypes. ABA content and ABA-dependent water deprivation responses were impaired in aoc shoots. Moreover, aoc accumulated more Na+ in roots, and less in leaf, with reduced ion translocation correlating with root derepression of the HAK4 Na+ transporter. Distinct reactive oxygen species scavengers were also stronger in aoc leaf, along with reduced senescence and chlorophyll catabolism markers. Collectively, the data identify contrasted contributions of JA signaling to different sectors of the salt stress response in rice