International Rice Research Institute, Los Baños, Laguna, Philippines.
Plant Physiol. 1971 Mar;47(3):404-8. doi: 10.1104/pp.47.3.404.
The levels of starch and dextrin, free sugars, soluble protein, and enzymes involved in starch metabolism-alpha-amylase, beta-amylase, phosphorylase, Q-enzyme, R-enzyme, and ADP-glucose starch synthetases-were assayed in the leaf sheaths and culm of the rice plant (Oryza sativa L., variety IR8) during growth.Starch accumulation in the leaf sheaths reached a maximum 10 to 11 weeks after transplanting, the time of development of the rice panicle. Maximal concentration of free sugars occurred earlier. Starch and sugars in the leaf sheaths and culm decreased rapidly during grain development.During starch accumulation, the starch granules of the leaf sheaths increased slightly in size and its gelatinization temperature decreased. The molecular size of amylose and amylopectin and amylose content of the starch were similar in both culm and leaf sheaths.Changes in the level of soluble protein paralleled changes in starch level in the leaf sheaths. Among the enzymes, only synthetase bound to the starch granule paralleled the level of starch in the leaf sheaths and in the culm. ADP-glucose, but not UDP-glucose, was utilized as a glucosyl donor by these starch synthetases. Zymograms of these extracts showed only one alpha-amylase band, one beta-amylase band, two phosphorylase bands, and one Q-enzyme band.
在水稻植株（Oryza sativa L.，品种 IR8）的叶片鞘和茎中，测定了淀粉和糊精、游离糖、可溶性蛋白以及参与淀粉代谢的酶——α-淀粉酶、β-淀粉酶、磷酸化酶、Q-酶、R-酶和 ADP-葡萄糖淀粉合酶——的水平。叶片鞘中的淀粉积累在移栽后 10 到 11 周达到最大值，此时是水稻穗的发育期。游离糖的最大浓度出现得更早。叶片鞘和茎中的淀粉和糖在籽粒发育过程中迅速减少。在淀粉积累过程中，叶片鞘中的淀粉颗粒大小略有增加，其糊化温度降低。茎和叶片鞘中淀粉的直链淀粉和支链淀粉的分子量以及直链淀粉含量相似。可溶性蛋白水平的变化与叶片鞘中淀粉水平的变化平行。在这些酶中，只有与淀粉颗粒结合的合酶与叶片鞘和茎中的淀粉水平平行。这些淀粉合酶利用 ADP-葡萄糖而不是 UDP-葡萄糖作为葡萄糖供体。这些提取物的同工酶图谱仅显示一条α-淀粉酶带、一条β-淀粉酶带、两条磷酸化酶带和一条 Q-酶带。
