TEMPORAL PATTERN OF JASMONATE-INDUCED ALTERATIONS IN GENE-EXPRESSION OF BARLEY LEAVES

Leaf tissues of barley (Hordeum vulgare L. cv. Salome) respond to meth yl jasmonate (JaMe) treatment with a characteristic pattern of gene ex pression. Jasmonate-induced proteins (JIPs), such as leaf thionins (ji p15 gene product) and ribosome-inactivating proteins (jip60 gene produ ct), rapidly accumulate. Their genes are transiently transcriptionally activated, as shown here by the determination of in-vitro transcripti on rates in run-off assays. In contrast to jip genes, expression of ph otosynthetic genes encoding the small subunit of ribulose-l,5-bisphosp hate carboxylase/oxygenase (rbcS gene product) and a type III light-ha rvesting chlorophyll-a/b-binding protein (LHCP; lhbC1 gene product), f or example, was rapidly down-regulated in JaMe-treated barley leaves. Despite decreasing rates of rbcS and lhbC1 gene transcription, their t ranscripts were maintained in JaMe-treated leaf tissues for at least 3 6 h. Only at a later stage, was there a decline in the levels of rbcS and lhbC1, but not jip, transcripts, suggesting a selective destabiliz ation of photosynthetic mRNAs in JaMe-treated leaf tissues.