不同类型玉米发育籽粒中淀粉合成及相关酶活性比较

摘要

以普通玉米、爆裂玉米、甜玉米和糯玉米为试材,分析和比较不同类型的玉米品种之间籽粒发育过程中淀粉合成及相关酶活性的变化.结果表明,淀粉合成速率和蔗糖合成酶(SS)、可溶性淀粉合成酶(SSS)、束缚态淀粉合成酶(GBSS)、淀粉分支酶(SBE)、去分支酶(DBE)活性都呈单峰曲线变化.30～40 DAP,普通玉米的SS活性显著高于其他3种类型;类型间平均和最大SSS活性水平的顺序为普通玉米》糯玉米》爆裂玉米》甜玉米;30～40DAP,普通玉米GBSS活性最高,糯玉米GBSS活性最低;20～40 DAP,糯玉米SBE活性最高;甜玉米的DBE活性很低,并且在40 DAP完全丧失.淀粉合成速率与SS、SSS、GBSS和SBE活性相关程度比较高,与腺苷二磷酸葡萄糖焦磷酸化酶(AGP酶)和:DBE活性相关不显著.推测AGP酶虽然为淀粉合成提供直接前体ADPG,但可能SS活性过低致使其限速作用比AGP酶的还强,AGP酶潜在的限速作用无法表现,SS成为玉米籽粒淀粉合成的限速因子.GBSS对直链淀粉积累起重要的促进作用;SSS和SBE对支链淀粉积累起重要的促进作用.%The relationships between the rates of starch synthesis and the activities of enzymes responsible for starch biosynthesis in developing grains of normal,pop,sweet and waxy corns were investigated and compared throughout the grain filling period.The results indicated that the rates of starch synthesis and the activities of SUcrose synthase(ss),soluble starch synthase(sss),granule-bound starch synthase(GBSS),starch-branching enzyme(SBE)and starch-debranching enzyme(DBE) each exhibited a single peak during grain filling period.Normal corn showed significantly higher SS activity than other genotypes between 30 and 40 DAp. The mean and maximum activities of SSS were in the following order:normal corn>waxycom>pop corn>sweet corn.GBSS activities were significantly higher in normal corn,and significantly lower in waxy corn at late filling period.SBE activity of waxy corn was significantly higher than other lines after 10 DAP.DBE activity of sweet corn was extremely lOW and completely lost at 40 DAP.The rates of starch synthesis had some correlation with the activities of SS,SSS,GBSS and SBE during the grain filling process.No correlation was found between the rates of starch synthesis and the activities of ADP-glucose pyrophosphorylase(AGPase)and DBE.SS activity appears to play a major role in starch biosynthesis in maize.GBSS is responsible for amylose synthesis especially in the later period.SSS and SBE are associated with amylopectin biosynthesis.