M. Robertson et al., SEQUENCE-ANALYSIS AND HORMONAL-REGULATION OF A DEHYDRIN PROMOTER FROMBARLEY, HORDEUM-VULGARE, Physiologia Plantarum, 94(3), 1995, pp. 470-478
A dehydrin gene (dhn7) was isolated from a barley (Hordeum vulgare L.
cv. Himalaya) genomic library. A 2138-bp fragment of the gene was sequ
enced and the deduced amino acid sequence showed 99% identity with tha
t of a previously identified cDNA, Dhn1, which encodes one of a group
of closely related proteins induced by dehydration stress. Transient e
xpression assays in barley aleurone protoplasts defined regions of the
dhn7 promoter that mediate abscisic acid (ABA) responsive transcripti
on. A fragment (-935 to +42) of the gene was found to confer concentra
tion-dependent ABA-responsiveness measured by expression of a beta-glu
curonidase (GUS) reporter gene. Analysis of a 5' deletion series of th
e promoter defined a region (-285 to -233) that modulated the amplitud
e of the ABA-response, whilst ABA-responsiveness, per se, required a r
egion (-233 to -211) that included a conserved motif containing the G-
box-like sequence TACGTGG. Gibberellic acid (GA(3)) antagonised ABA-in
duced accumulation of dehydrin mRNA in aleurone cells, but did not ant
agonise ABA-induced transcriptional activation as revealed by GUS acti
vity. The antagonistic effect of GA(3) on ABA-induced dehydrin express
ion might therefore operate post-transcriptionally.