ISOLATION, CHARACTERIZATION AND EXPRESSION OF A CDNA CODING FOR A JASMONATE-INDUCIBLE PROTEIN OF 37-KDA IN BARLEY LEAVES

In barley leaves, there is a dramatic alteration of gene expression up on treatment with jasmonates leading to the accumulation of newly form ed proteins, designated as jasmonate-inducible proteins (JIPs), In the present study, a new jasmonate-inducible cDNA, designated pHvJS37, ha s been isolated by differential screening of a lambda gt10 cDNA librar y constructed from mRNA of jasmonate-treated barley leaf segments, The open reading frame (ORF) encodes a 39 . 9 kDa polypeptide which cross -reacts with antibodies raised against the in vivo JIP-37, The hydropa thic plot suggests that the protein is mainly hydrophilic, containing two hydrophobic domains near the C-terminus, Database searches did not show any sequence homology of pHvJS37 to known sequences, Southern an alysis revealed at least two genes coding for JIP-37 which map to the distal portion of the long arm of chromosome 3 and are closely related to genes coding for JIP-23, The expression pattern of the JIP-37 gene s over time shows differential responses to jasmonate, abscisic acid ( ABA), osmotic stress (such as sorbitol treatment) and desiccation stre ss, No expression was found under salt stress, From experiments using an inhibitor and intermediates of jasmonate synthesis such as alpha-li nolenic acid and 12-oxophytodienoic acid, we hypothesize that there is a stress-induced lipid-based signalling pathway in which an endogenou s rise of jasmonate switches on JIP-37 gene expression, Using immunocy tochemical techniques, JIP-37 was found to be simultaneously located i n the nucleus, the cytoplasm and the vacuoles.