TEMPORAL AND SPATIAL EXPRESSION OF THE ALPHA-AMYLASE GENE DURING SEED-GERMINATION IN RICE AND BARLEY

We have analyzed the in situ hybridization of alpha-amylase genes in r ice and barley seeds. There are some similarities in the expression pa ttern between the rice and barley alpha-amylase genes, RAmy1A and Amy1 . Both are gibberellin-inducible, the expression of these genes initia tes in the scutellar epithelium and continues in the aleurone layer, a nd the gene expression in the aleurone layer initiates from a region c lose to the embryo. However, we also identified some differences in th e pattern of gene expression between these species. (i) expression of the rice a-amylase gene is initiated in the terminal regions of scutel lar epithelium, but in the middle-basal region in barley, (ii) the pro gress of the gene expression in the rice aleurone layer is faster than that in barley. Additionally, analyses using embryo mutants of rice i ndicate that the scutellum has a responsibility for RAmy1A gene expres sion in aleurone layer cells.