JASMONATE-RESPONSIVE GENE-EXPRESSION IN BARLEY

The effect of phytohormones on specific gene expression was studied in order to (a) elucidate molecular mechanism(s) of hormone action and ( b) develop inducible promoter cassettes for transgene expression. As p art of this work, we have studied a jasmonate-responsive barley gene, the expression of which may also be induced during senescence, woundin g, and pathogen attack. To date, we have isolated a jip23 genomic clon e and sequenced 2 kb of 5' upstream and the first two exons. In order to attempt to delineate a jasmonate-responsive DNA element and to deve lop a minimal promoter cassette, we are testing jip23 promoter/GUS (or CAT) reporter genes in aleurone protoplasts and young leaves by parti cle bombardment. We have also analyzed the effect of jasmonate, abscis ic acid, and gibberellin on the expression of jip23 and other genes to study the complexity of hormonal responses and their modulation by in teracting or interfering signal transduction pathways.