水分胁迫下糜子籽粒淀粉合成关键酶及与灌浆特性的关联
Activities of Key Enzymes for Starch Synthesis and Grain-filling Characteristics under Water Stress in Broomcorn Millet.

以‘榆糜2号’为材料，采用盆栽试验，以正常供水为对照，研究拔节期中度和重度水分胁迫、抽穗期中度和重度水分胁迫对糜子籽粒淀粉合成关键酶活性变化和籽粒灌浆特性。结果表明：水分胁迫抑制糜子籽粒灌浆过程中的淀粉分支酶（Q酶）、蔗糖合成酶（SS）、ADP-葡萄糖焦磷酸化酶（AGPP）3种酶活性，不同胁迫程度相比，重度水分胁迫对淀粉合成关键酶活性影响较大，中度水分胁迫次之；不同胁迫时期相比，拔节期水分胁迫对淀粉合成关键酶活性影响较大，抽穗期水分胁迫次之。3个酶的变化与籽粒灌浆动态相关联，Q酶和蔗糖合成酶活性峰值出现的时间在糜子籽粒最大灌浆速率出现的时间之后，AGPP最高活性出现的时间提前或同步于最大灌浆速率的时间。相关分析表明，Q酶、SS和AGPP活性与平均灌浆速率和最大灌浆速率均呈显著或极显著正相关。可见，水分胁迫使糜子籽粒淀粉合成关键酶活性受到抑制，从而导致籽粒灌浆速率和产量降低。
Using millet variety ‘Yumi 2’ as material and normal water supply as control,under condition of moderate and severe water stress at stages of jointing and heading,a plot experiment was conducted to study the activity changes of key enzymes for starch synthesis and grain-filling characteristics in broomcorn millet.The results showed that water stress decreased activities of starch branching enzyme (Q-enzyme),sucrose synthase (SS) and ADPG pryophosphorylase (AGPP),and the severe water stress had a great effect on activities of key enzymes for starch synthesis compared with the moderate water stress,and the effect of water stress at jointing stage on activities of key enzymes for starch synthesis was more great than that of water stress at heading stage.The changes of three enzyme activities were associated with grain filling process.The appearance time of maximum Q-enzyme and SS activities were later than that of maximum grain-filling rate in broomcorn millet,and the time which reached maximum of AGPP activity was earlier than or synchronous with time which reached maximum grain-filling rate.The correlation analysis indicated that activities of Q-enzyme,SS and AGPP had significant or very significant positive correlation with average grain-filling rate and maximum grain-filling rate.The water stress inhibited the activities of key enzymes for starch synthesis,thus decreased grain-filling rate and yield of broomcorn millet.