Characterization of beta-amylase and its deficiency in various rice cultivars

beta-Amylase deficiency in various cultivars of rice was examined at the mo lecular level. Using an antibody against beta-amylase purified from germina ting seeds of rice, we were able to demonstrate the expression and organiza tion of the beta-amylase gene in normal and deficient cultivars. Although b eta-amylase is a starch-hydrolyzing enzyme, as is alpha-amylase, the beta-a mylase protein/gene is expressed differently from the alpha-amylase protein /gene; i.e. (1) beta-amylase is synthesized only in aleurone cells, (2) the enzyme production in the embryo-less half-seeds is not under hormonal cont rol, We identified some cultivars of rice that are deficient for beta-amyla se activity. We present new evidence that synthesis is blocked at the level of mRNA synthesis in the deficient cultivars. The usefulness of beta-amyla se as a crop trait is also discussed.