course very close to that for the formation of native a-amylase. Promoter
deletions (see Section 2.3.5.1) reveal that a region extending to -300 bp upstream
of the transcription start site is sufficient to drive GA-regulated expression which
can be prevented by the inclusion of ABA in the incubation medium. Using a
similar approach, it has been shown that a major GA-response element (GARE)
in the 5' upstream promoter of the high-pi barley a-amylase gene is located
between — 148 and -128 bp from the transcription start site; a construct consisting
of six copies of the region fused to CAT is also sensitive to ABA, which
suppresses GA action. In another high-pi barley a-amylase, the GARE is in the
region -174 to -108, and this again has sensitivity to ABA (Fig. 8.7).