Salt stress is an increasing environmental threat in coastal agriculture, and can result in considerable yield losses. Jasmonate (JA) hormones are well known for positively regulating plant defenses against attacks by herbivores or pathogenic microorganisms, but their involvement in salt tolerance is still debated.
In a study published in the Journal of Experimental Botany on March 4, 2023, in collaboration with scientists from the Botanical Institute of the Karlsruhe Institute of Technology (KIT) in Germany and from the Institut pour la Recherche et le Développement (IRD) in Montpellier, work conducted at IBMP sheds new light on the impacts of JA signaling on salt tolerance. Starting from the initial observation that a JA-deficient mutant line exhibits milder damage symptoms than wild-type rice, the consortium has dissected at the phenotypic, transcriptome, and metabolic levels the biological processes regulated by JAs. It appeared that JA signaling is essential with abscisic acid to respond to the osmotic component (water deprivation) of salt stress. Conversely, JA signaling promotes collapse of the photosynthetic machinery, resulting in senescence, and inhibits the expression of factors required to combat ionic component of salt stress such as sodium transporters or reactive oxygen species detoxifying enzymes. These findings identify new physiological processes regulated by JAs and help to understand how they influence the osmotic (rapid) and ionic (slow) phases of salt stress.