土壤质地对小麦SPS、SS活性及其与淀粉合成关系的影响

在池栽条件下, 研究了黏壤土、中壤土和沙壤土对豫麦49灌浆期旗叶、旗叶鞘、穗茎和籽粒中蔗糖代谢关键酶蔗糖磷酸合酶(SPS)和蔗糖合酶(SS)的活性变化。结果表明, 在3种不同质地土壤上, 小麦灌浆期各器官中SPS和SS活性均呈单峰曲线变化。沙壤土上除了籽粒中SPS活性略低于中壤土外, 其他部位酶活性均最高; 而中壤土籽粒中SPS在灌浆前期及SS在灌浆中后期的活性显著高于其他壤土。中壤土和沙壤土上小麦千粒重和籽粒淀粉含量均显著高于黏壤土, 但中壤土和沙壤土间差异不显著。说明中壤土和沙壤土对小麦的蔗糖合成与降解有一定的影响, 沙壤土有利于小麦营养器官中蔗糖的合成, 而中壤土对小麦籽粒中蔗糖的合成比较有利。相关分析表明, 沙壤土和中壤土上SPS、SS活性与小麦籽粒灌浆速率、支链淀粉和总淀粉积累速率均达显著或极显著相关; 而在黏壤土上, 酶活性与总淀粉积累速率的相关系数(除籽粒SPS外)未达显著水平或相关性小于在其他2种土壤上。中壤土和沙壤土上小麦营养器官中SPS催化的蔗糖合成代谢和籽粒中SS催化的蔗糖降解代谢对籽粒淀粉和支链淀粉的积累具有十分重要的作用。

Effects of Soil Texture on ActiVities of SPS,SS,and Relationship with Starch Accamulation during Grain Filling in Wheat

A wheat (Triticum aestivum L.) cultivar, Yumai 49 was used in a pool experiment to investigate the activities of key enzymes involved in sucrose metabolism in leaf, sheath, stem, and grain during grain filling in clay-loam, mid-loam, and sand-loam soils. The changes of sucrose phosphate synthase (SPS) and sucrose synthase (SS) activities in different organs during grain filling in three types of soil showed a single-peak curve. In the sand-loam soil, SPS activities were the highest in different organs expect grains. In the mid-loam soil, the SPS activity in grains at the early filling stage and the SS activity at the medium-to-late filling stages were significantly higher than those in the clay-loam soil. The 1000-grain weight and starch content in the mid-loam soil and sand-loam soil were significantly highter than those in the clay-loam soil, but those were not significantly different between mid-loam soil and sand-loam soil. This showed that the mid-loam soil and sand-loam soil could affect the sucrose synthesis and degradation in Yumai 49. The sand-loam soil was available for sucrose synthesis in the vegetative organs of wheat, but the mid-loam soil was available for sucrose synthesis in grains of wheat. The SPS and SS activities all correlated significantly or very significantly with grain filling rate, amylopectin and starch accumulation rates in grains in the mid-loam soil and sand-loam soil, but the correlation between the enzymes activities, expect SPS activities in grains, and starch accumulation rate was not significant. It is more important for the sucrose synthesis catalyzed by SPS in the vegetative organs and the sucrose degradation catalyzed by SS in grains to accumulate the starch and amylopectin in grains of wheat in the mid-loam soil and sand-loam soil.