小麦灌浆期蔗糖代谢关键酶活性变化及其与籽粒淀粉积累的关系

在池栽条件下，研究了藁城8901(强筋品种)、豫麦49(中筋品种)和洛麦1号(弱筋品种)小麦灌浆期旗叶、叶鞘、穗茎、籽粒蔗糖磷酸合酶(SPS)、蔗糖合酶(SS)活性变化及其与淀粉及组分积累的关系。结果表明，其SPS和SS活性变化均呈单峰曲线。豫麦49旗叶、旗叶鞘和籽粒中及洛麦1号穗茎中SPS酶活性较高。豫麦49的旗叶、旗叶鞘、穗茎和籽粒中SS活性高于其他两品种，表明豫麦49和洛麦1号营养器官和籽粒中蔗糖合成和降解代谢比较活跃。相关分析表明，豫麦49和洛麦1号籽粒中淀粉和支链淀粉积累对SPS催化的蔗糖合成过程具有较强的反馈调节作用。豫麦49和洛麦1号籽粒中SS活性均与总淀粉与支链淀粉积累速率极显著正相关，而在藁城8901中无此相关性。

Dynamic Changes of Activities of Key Enzymes Involved in Sucrose Metabolism during Grain Filling in Wheat and the Relationship with Starch Accumulation in Grain

Sucrose and starch are the main product of wheat photosynthesis. During sucrose metabolism, Sucrose phosphate synthase (SPS) is the key enzyme controlling sucrose synthesis, but sucrose synthase (SS) is the key enzyme controlling sucrose degradation. In the present experiment conducted in cement cultural pool, three winter wheat (Triticum aestivum L.) cultivars GC8901 (strong gluten), YM49 (medium gluten) and LM1 (weak gluten) were used to investigate the activities of the key enzymes involved in sucrose metabolism in leaf, sheath, ear stem and grain during grain filling and the relationship with starch accumulation in grain. Ten main tillers of each plot were sampled at 6, 12, 18, 24, 30, and 36 days after anthesis, and partitioned into flag leaf, sheath of flag leaf, and ear stem.One hundred grains of each plot were sampled from the spikes from which only two basal grains of the 4th to 12th spikelets were collected. Half of the plant samples were used to determinate the enzyme activities, and the other half for starch content measurement.In the three cultivars, the dynamic changes of activities of sucrose phosphate synthase(SPS) and sucrose synthase(SS) in leaf, sheath, ear stem and grain during grain filling period all fit the single-peak curve. The SPS activity in flag leaf, flag leaf sheath and grain of YM49 was higher than that of other two cultivars, but the SPS activity in ear stem of LM1 was higher than that of other two cultivars. The SS activity in flag leaf, flag leaf sheath, ear stem and grain of YM49 was higher than that of other two cultivars,indicating the sucrose synthesis and degradation in the vegetative organs and grain of YM49 and LM1 were active. Correlation analysis showed that the starch and amylopectin accumulation in the grain of YM49 and LM 1 had strong feedback regulation to sucrose synthesis catalyzed by SPS. The SS activities in the grain of YM49 and LM1 were significantly(P<0.01) correlated with the starch and amylopectin accumulating rate, but that of GC8901 was not. The results suggested that the SPS and SS activities in the vegetative organs and grain in three different wheat cultivars were closely related to starch accumulation.