以均含有3个Waxy蛋白亚基的普通小麦品种济麦20（低直链淀粉含量）和鲁麦21（高直链淀粉含量）为材料，对灌浆期籽粒淀粉合成相关酶活性的变化及淀粉积累特征进行了研究，并分析了两者之间的关系。结果表明，蔗糖合成酶(SS)、腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、束缚态淀粉合成酶(GBSS)、可溶性淀粉合成酶(SSS)和淀粉分支酶(SBE)活性均呈单峰曲线变化。鲁麦21的上述酶活性均高于济麦20。相关分析表明，支链淀粉积累速率与SS、AGPP、SSS和SBE呈显著或极显著正相关；直链淀粉积累速率与SS、AGPP和GBSS呈极显著正相关。Logistic方程拟合淀粉积累过程发现，支、直链淀粉最终积累量的高低取决于积累启动时间的早晚和积累速率的高低，而积累持续期的调节作用较小。直链淀粉的积累速率除受GBSS活性影响外，还受SS和AGPP活性的影响，其中，GBSS活性的变化与2品种籽粒直链淀粉积累量的变化情况基本吻合。籽粒灌浆后期的GBSS活性对直链淀粉最终积累量的调节作用大于灌浆前期，说明对同时具有3个Waxy蛋白亚基的不同品种，Waxy蛋白亚基表达量(GBSS活性)的差异可能是导致品种间籽粒直链淀粉含量较大差异的一个关键原因。
The amylose content of wheat grain is significantly correlated with amount of Waxy protein subunit. However, there is a great difference in amylose content among different wheat cultivars which all have three Waxy genes. In order to investigate the activity changes of enzymes involved in starch biosynthesis, the characteristics of starch accumulation in grains, and the relationship between them, two wheat (Triticum aestivum L.) cultivars, JM20 (lower amylose content in grains) and LM21 (higher amylose content in grains) were used in the study, which both carry three Waxy protein subunits. The results indicated that the activities of sucrose synthase (SS), adenosine diphosphorate glucose pyrophrylase (AGPP), soluble starch synthase (SSS), granule-bound starch synthase (GBSS) changed in the pattern of a single-peak curve during grain filling. The activities of SS, AGPP, GBSS, SSS and SBE in LM21, which had higher starch content, were higher than those in JM20. The accumulation rate of amylopectin was significantly or highly significantly correlated with the activities of SS, AGPP, SSS and SBE, and the accumulation rate of amylose was highly significantly correlated with the activities of SS, AGPP and GBSS. The accumulation courses of both amylopectin and amylose were well fitted to the logistic equation by relating amylopectin and amylose contents against days post anthesis. The simulation parameters revealed that the higher contents of amylopectin and amylose resulted from earlier initiating accumulation time and greater accumulation rate, but accumulation duration probably played a less important role for them. The amylose content in grains was mainly determined by GBSS activity as well as the activities of SS and AGPP. The change of GBSS activity reflected expression level of waxy gene was closely associated with the accumulation rate of amylose, indicating that amylose content in grains was determined by GBSS activity, especially at late grain filling stage. The difference in expression of waxy gene might be a major reason for the large difference in amylose contents between JM20 and LM21.
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