A COMPARISON OF ALPHA-AMYLASE ISOZYME PROFILES IN SELECTED SU AND HIGH-SUGAR SWEET CORN (SH-2, SU-1, SU-1 SE) LINES (ZEA-MAYS L)

Alpha-Amylases were purified from germinating starchy (Su) maize kerne ls (Funks G4646) using glycogen precipitation and preparative SDS-PAGE . Antiserum to the purified a-amylases was produced in rabbits. Isozym es of alpha-amylase from the scutellum and aleurone tissues of kernels of five Su lines were compared with a sweet corn (su-1) and two high- sugar sweet corn (su-1 se and sh-2) inbred lines in the same genetic b ackground, using isoelectric focusing gels, starch zymograms, and immu noblotting analyses. The most notable differences were found in the hi gh-sugar sweet corn kernels. In the sh-2 aleurone, there were no alpha -amylase isozymes detected on the zymogram and immunoblot, indicating a lack of enzyme accumulation. In the su-1 se scutellum, there were fe wer isozymes compared with most of the lines examined, but the signifi cance of this is not clear. Comparison of the five Su lines revealed s everal isozymes common to all the kernels examined, but there were con siderable tissue-specific differences in the number of isozymes betwee n the aleurone and scutellum tissues. The Funks G4646 (Su) and RB-4 (S u) had similar scutellar and aleurone isozyme patterns, with the aleur one having one more isozyme than the scutellum. In OH43 (Su) kernels, the scutellum had one to two more isozymes with (alpha-amylase activit y than the aleurone, while the IL451b (Su) scutellum had fewer isozyme s (seven to eight) than the aleurone (14-16). Both high- and low-pl is ozymes of wheat and barley, and the low-pl isozymes of rice, were reco gnized by the antibodies to maize alpha-amylases developed in this stu dy. These data indicate a complex relationship between the carbohydrat e and sugar composition of the kernel and the synthesis of alpha-amyla se isozymes during germination.