DEVELOPMENTAL AND HORMONAL-REGULATION OF RICE ALPHA-AMYLASE(RAMY1A)-GUSA FUSION GENES IN TRANSGENIC RICE SEEDS

Transgenic seeds of rice (Oryza sativa L.) were used to investigate te mporal, spatial, and hormonal regulation of a rice Lu-amylase gene, RA my1A. Two overlapping segments of the RAmy1A promoter were fused to th e coding region of the bacterial reporter gene, gusA. The resulting pr omoter-gusA fusions, pE4/GUS (-232 to +31) and pH4/GUS (-748 to +31), were used separately to transform rice protoplasts. beta-Glucuronidase (GUS) activity was detected in germinated transgenic seeds, although the two constructs showed no significant difference in timing or locat ion of GUS expression. Both constructs first expressed GUS in the scut ellar epithelium and then in the aleurone layer. Aleurone expression o f GUS activity was strongly induced when embryoless half-seeds were tr eated with gibberellic acid. GUS expression in the aleurone layer was also suppressed by abscisic acid. These results indicate that the 5' r egulatory region from -232 to +31 is sufficient for temporal, spatial, and hormonal regulation of RAmy1A gene expression.