Differential accumulation of methyl jasmonate‐induced mRNAs in response to abscisic acid and desiccation in barley (Hordeum vulgare)

Upon treatment with abscisic acid (ABA) or as a result of water stress (desiccation) detached leaf segments of barley (Hordeum vulgare L. cv. Salome) synthesized proteins of Mr 66000, 37000, 30000 and 23000 which had previously been characterized as abundant methyl jasmonate (JaMe)‐induced proteins. The time course of appearance of mRNAs encoding JaMe‐induced proteins was compared under the three different treatments, i.e. JaMe, ABA and desiccation. From the overall analysis by in vitro translation, a complex alteration in the leaf mRNA population became evident that depended on the treatment employed. mRNAs likewise induced by the various treatments could be discriminated from mRNAs appearing specifically after JaMe‐ or ABA‐treatment or in response to desiccation. For two mRNAs induced by JaMe, ABA and desiccation, sequence homology was suggested to transcripts encoding late embryogenesis abundant (LEA) proteins. The two transcript species of 2.17 kb and 1.28 kb detected with a synthetic Lea gene‐specific probe in northern blot hybridizations appeared with different time courses and accumulated to different extents under the various treatments, highlighting the obvious diversity of Lea gene expression in response to ABA, JaMe and desiccation. We suggest a role of jasmonates in mediating water stress reactions in vegetative tissues of barley.