Drought tolerance involve fine modulation of jasmonates in oat roots and leaves

Abstract

Jasmonates (JA), include a diverse group of jasmonic acid derivatives, such as Ile-jasmonic or dihydrojasmonic acid and its biosynthetic intermediate, 12-OPDA. Recent data indicate an involvement of JA in drought tolerance responses. However, controversy has arisen regarding the effect of JA in drought tolerance since some studies have reported improved drought tolerance whereas others reported negative effects associated with growth and yield reductions. Observed differences rely mainly in the plant species and tissue, and in the intensity and duration of the drought stress imposed. In this work, we investigated dynamic changes in JA profile of oat plants, including roots and leaves of two well-characterized genotypes for drought resistance, over a 20 days-time course. In leaves, Jasmonic acid and Ile-jasmonic increased only in the resistant genotype as relative water content in the soil (sRWC) decreased from 40% downward, whereas both reduced their content progressively in roots in a similar proportion in both genotypes. No changes were observed regarding dihydrojasmonic acid. Interestingly, a similar increase of OPDA was detected in leaves of both genotypes while it accumulated differently in roots. Whereas a dramatic reduction was observed in the tolerant genotype an increase of OPDA was observed in the susceptible one. Since JA and particularly OPDA have been linked with root growth inhibition, their reduction in roots could explained the already observed increased root growth of the tolerant genotype. Currently experiments are being carried out to confirm this hypothesis.