Konik-Rose Christine, Thistleton Jenny, Chanvrier Helene, Tan Ihwa, Halley Peter, Gidley Michael, Kosar-Hashemi Behjat, Wang Hong, Larroque Oscar, Ikea Joseph, McMaugh Steve, Regina Ahmed, Rahman Sadequr, Morell Matthew, Li Zhongyi
CSIRO Food Futures Flagship, PO Box 93, North Ryde, NSW 1670, Australia.
Theor Appl Genet. 2007 Nov;115(8):1053-65. doi: 10.1007/s00122-007-0631-0. Epub 2007 Aug 25.
Starch synthases (SS) are responsible for elongating the alpha-1,4 glucan chains of starch. A doubled haploid population was generated by crossing a line of wheat, which lacks functional ssIIa genes on each genome (abd), and an Australian wheat cultivar, Sunco, with wild type ssIIa alleles on each genome (ABD). Evidence has been presented previously indicating that the SGP-1 (starch granule protein-1) proteins present in the starch granule in wheat are products of the ssIIa genes. Analysis of 100 progeny lines demonstrated co-segregation of the ssIIa alleles from the three genomes with the SGP-1 proteins, providing further evidence that the SGP-1 proteins are the products of the ssIIa genes. From the progeny lines, 40 doubled haploid lines representing the eight possible genotypes for SSIIa (ABD, aBD, AbD, ABd, abD, aBd, Abd, abd) were characterized for their grain weight, protein content, total starch content and starch properties. For some properties (chain length distribution, pasting properties, swelling power, and gelatinization properties), a progressive change was observed across the four classes of genotypes (wild type, single nulls, double nulls and triple nulls). However, for other grain properties (seed weight and protein content) and starch properties (total starch content, granule morphology and crystallinity, granule size distribution, amylose content, amylose-lipid dissociation properties), a statistically significant change only occurred for the triple nulls, indicating that all three genes had to be missing or inactive for a change to occur. These results illustrate the importance of SSIIa in controlling grain and starch properties and the importance of amylopectin fine structure in controlling starch granule properties in wheat.
淀粉合酶（SS）负责延长淀粉的α-1,4葡聚糖链。通过将每个基因组（abd）上缺乏功能性ssIIa基因的小麦品系与每个基因组（ABD）上具有野生型ssIIa等位基因的澳大利亚小麦品种Sunco杂交，产生了一个双单倍体群体。先前已有证据表明，小麦淀粉颗粒中存在的SGP-1（淀粉颗粒蛋白-1）蛋白是ssIIa基因的产物。对100个后代品系的分析表明，来自三个基因组的ssIIa等位基因与SGP-1蛋白共分离，进一步证明SGP-1蛋白是ssIIa基因的产物。从后代品系中，选取了40个代表SSIIa八种可能基因型（ABD、aBD、AbD、ABd、abD、aBd、Abd、abd）的双单倍体品系，对其粒重、蛋白质含量、总淀粉含量和淀粉特性进行了表征。对于某些特性（链长分布、糊化特性、膨胀力和凝胶化特性），在四类基因型（野生型、单缺失、双缺失和三缺失）中观察到了渐进变化。然而，对于其他籽粒特性（种子重量和蛋白质含量）和淀粉特性（总淀粉含量、颗粒形态和结晶度、颗粒大小分布、直链淀粉含量、直链淀粉-脂质解离特性），只有三缺失基因型出现了统计学上的显著变化，这表明所有三个基因都必须缺失或缺失或失活才会发生变化。这些结果说明了SSIIa在控制籽粒和淀粉特性方面的重要性，以及支链淀粉精细结构在控制小麦淀粉颗粒特性方面的重要性。
