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

Study on Key Starch Degrading Enzyme Activity and Related Gene Expression Level during Early Germination Stage of Wheat Seed

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。

Shannong17 was used to investigate the activities of key enzymes and expression levels of related genes of starch degradation during early germination stage of wheat seed. The contents of starch and soluble sugar and the activities of starch degradation enzymes were determined in germinating wheat seeds at different 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 of α - amylase and starch phosphorylase and the respiration rate kept increasing with the process of germination. Obvious changes of these indicators were found during the period of visible radicle protrusion through the seed coveting layers. The activity of β- amylase demonstrated a double - peak curve and kept highly active during 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 ot - amylase and starch phosphoryl- ase which olaved imnortant roles during germination could be detected at the initial period of germination andwere regulated greatly by its encoding genes.