小麦不同灌浆速率品种籽粒淀粉合成与积累研究

Studies on starch biosynthesis and accumulation in wheat varieties with different grain-filling rates

为探明小麦(Triticum aestivum)不同灌浆速率品种籽粒淀粉合成与积累差异的生理基础,本研究以长江中下游麦区灌浆速率较快的品种‘扬麦16’和‘扬麦23’为材料,以灌浆速率较慢的‘扬麦15’和‘宁麦13’为对照,测定不同灌浆时间籽粒中淀粉含量,通过树脂半薄切片和扫描电镜观察胚乳淀粉体发育特征,采用荧光定量PCR测定灌浆期籽粒淀粉合成酶基因相对表达量,并测定淀粉合成关键酶活性。结果表明:‘扬麦16’和‘扬麦23’灌浆盛期单粒淀粉合成量大于对照,形态学表现为胚乳细胞内淀粉体大,充实快,且B型淀粉体形成早,淀粉体总体发育进程快。灌浆前中期,‘扬麦16’和‘扬麦23’中AGPaseI、GBSSI、SSSIII、SBEI等4种基因表达量总体高于对照,并且ADP-葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)、结合态淀粉合成酶(GBSS)和淀粉分支酶(SBE)活性也均高于‘扬麦15’和‘宁麦13’。本研究表明,‘扬麦16’和‘扬麦23’灌浆期淀粉体较大、淀粉合成关键酶活性高是淀粉合成与积累快的主要原因。

In order to uncover the differences of starch biosynthesis and accumulation in wheat(Triticum aestivum) varieties with different grain-filling rates, we preformed phenotypic, physiologic and molecular analyses using four wheat varieties of ’Yangmai16’, ’Yangmai23’, ’Yangmai15’ and ’Ningmai13’. On the basis of analyzation of starch contents during grain filling, the development of starch granule in endosperm cells of caryopsis were observed by semi-thin section method and scanning electron microscopy(SEM).The key enzyme activities of starch biosynthesis and the relative expression of genes were detected. The results show that, compared to the control cultivars of ’Yangmai15’ and ’Ningmai13’, the starch contents per grain of ’Yangmai 16’ and ’Yangmai 23’ were larger and increased faster. In the endosperm cells of ’Yangmai16’ and ’Yangmai23’, the starch granules developed with larger size and faster filling. Meanwhile, the B-type starch granules appeared earlier, which generally indicates a faster developmental process of starch granules. The expression levels of AGPaseI, GBSSI, SSSIII and SBEI were significantly higher in the early and middle stages of grain filling. Moreover, the activities of ADP-glucose pyrophosphorylase(AGPase), soluble starch synthase(SSS), granule-bound starch synthase(GBSS) and starch-branching enzyme(SBE) were also higher in the seeds of ’Yangmai 16’ and ’Yangmai 23’. Our results demonstrate that the larger starch granule size and higher activities of starch biosynthetic enzymes during the filling period of ’Yangmai 16’ and ’Yangmai 23’ are mainly responsible for the fast starch biosynthesis and accumulation, as well as the faster grain filling.