水稻发育胚乳中淀粉的积累及淀粉合成的酶活性变化

利用４个粒重相近品种（组合），对胚乳发育期间蔗糖、可溶性糖的淀粉含量、籽粒灌浆速率及与淀粉合成有关的６个酶活性的变化进行了研究。结果表明，品种间及不同剪叶处理间强势粒的淀粉积累和酶活性差异较小，而弱势粒差异明显。蔗糖合成酶，ＡＤＰＧ焦磷酸化酶、可溶态淀粉合成酶、淀粉分枝酶（Ｑ酶）、活性的变化与灌浆速率曲线十分吻合，相关性极显，而ＵＤＰＧ焦磷酸化酶活性变化与灌浆速率曲线吻合性较差。结合态淀粉合成酶

Starch Accumulation and Changes in Enzyme Activities Involved in Starch Synthesis During the Development of Rice Endosperm

The Contents of sucrose, soluble sugar and starch, grain filling tate, and the changes in activities of 6 enzymes involved in starch synthesis during the development of rice endosperm were analyzed with 4 cultivars of rice whose grain weights are similar. There were less difference in starch accumulation and enzyme activities in superior caryopses among the 4 cultivars as well as among different treatments of defoliation, but the differences in inferior caryopses were obvious. The change patterns of sucrose synthase, ADPglucose pyrophosphorylase, soluble starch synthase and starch branching enzyme (Q enzyme) correlated well with the curve of grain filling rate. There was no significant correlation between the activity of UDPglocuse pyrophosphorylase and grain filling rate. The activities of insoluble starch synthase increased with the development of endosperm, and a significant correlation was found between the mean activity and amylose content in endosperm of 35 th day after anthesis. The results strongly suggest that ADPglucose pyrophosphorylase, soluble starch synthase, sucrose synthase and Q enzyme play a key role in starch synthesis of rice endosperm. And the insoluble starch synthase is mainly response for the synthesis of amylose in endosperm. The decreases of activity of enzymes and starch accumulation in inferior caryopses followed the defoliation, which suggests that the supply of assimilate from source plays a very important role in the development of endosperm.