小麦种子萌发早期淀粉降解关键酶活性及基因表达量研究

摘要

Shannong17 was used to investigate the activities of key enzymes and expression levels of re-lated genes of starch degradation during early germination stage of wheat seed .The contents of starch and solu-ble sugar and the activities of starch degradation enzymes were determined in germinating wheat seeds at differ -ent temperatures;their related gene expression levels were detected by real -time fluorescence quantitative PCR.The results showed that the starch content decreased at different rates with the germination process at different temperatures;the soluble sugar content decreased at first and then increased;the activities ofα-am-ylase and starch phosphorylase and the respiration rate kept increasing with the process of germination .Obvi-ous changes of these indicators were found during the period of visible radicle protrusion through the seed cov -ering layers.The activity of β-amylase demonstrated a double -peak curve and kept highly active during germination.The relative gene expression level of starch degradation enzyme (except β-amylase) increased with the process of germination , and was significantly correlated with the activities of responded enzymes .In conclusion , the relative gene expression levels of the key starch degradation enzymes were affected strongly by temperature at the early stage of wheat seed germination .The activities of α-amylase and starch phosphoryl-ase which played important roles during germination could be detected at the initial period of germination and were regulated greatly by its encoding genes.%为研究小麦种子萌发早期淀粉降解关键酶活性及其基因表达量变化，以山农17为试验材料，测定了不同温度条件下萌发的小麦种子中的淀粉、可溶性糖含量及相关酶（淀粉酶和淀粉磷酸化酶）活性，并采用实时荧光定量PCR技术测定各酶相关基因相对表达量。结果显示，不同温度条件下萌发的小麦种子，淀粉含量随萌发进程以不同的速率呈下降趋势，可溶性糖含量呈先下降后上升趋势，α-淀粉酶、淀粉磷酸化酶活性和呼吸速率整体呈上升趋势，以上各指标均在露白前后有明显的变化；β-淀粉酶呈现双峰变化趋势，且一直保持较高活性；α-淀粉酶和淀粉磷酸化酶基因的相对表达量均呈上升趋势，且与酶活性呈极显著相关。以上结果表明，在小麦种子萌发早期，温度能强烈影响萌发过程中淀粉降解关键酶基因的表达量；α-淀粉酶和淀粉磷酸化酶在种子置床初期即可被检测到活性，且受其编码基因的调控作用显著，在种子萌发过程中具有重要作用。