关键词: 玉米, 籽粒, 直链淀粉, 支链淀粉, 灌浆速率, 酶活性

Abstract: Two types of maize cultivars, high starch maize (Feiyu3) and normal maize (Yuyu22) were used in the present study. The changes of enzyme activities associated with sucrose metabolism and starch biosynthesis in developing kernel were investigated. Grain filling rate and starch accumulation were analyzed. The results showed that sucrose transport capacity, grain filling rate, starch accumulation rates and the activities of sucrose synthase (SS), granule-bound starch synthase (GBSS), starch branching enzyme (SBE) of Feiyu3, which has high starch content, were significantly higher than those of Yuyu22, that has low starch content, after 10DAP. Correlation analysis indicated that ADP-glucose pyrophosphorylase (AGPase) and starch debranching enzyme (DBE) were not correlated with starch accumulation rates and grain filling rate, but SS activity and sucrose transport capacity at the middle and late period were highly significantly correlated with starch accumulation rates and grain filling rate. GBSS activity was highly significantly correlated with amylose accumulation rate, but not correlated with grain filling rate. SBE activities were highly significantly correlated with amylopectin accumulation rate. These showed that it was not AGPase and DBE, but SS and sucrose transport capacity was the rate-limited factor of starch biosynthesis in maize kernel. GBSS had an important effect on amylose accumulation, SBE had a significant effect on the amylopectin accumulation.

Key words: Maize, Kernel, Amylose, Amylopectin, Grain filling rate, Enzymes activities