School of Agronomy, Shihezi University, Shihezi, 832 003 China.
J Food Sci Technol. 2014 Mar;51(3):419-29. doi: 10.1007/s13197-011-0520-z. Epub 2011 Sep 28.
In order to investigate starch accumulation, and the enzymes activity changes and the expression levels of genes and their relationships among them at different developmental stages of wheat grain. We choose Annong9912 and E28 were used in the study. During starch accumulating rate and grain filling rate, and there were obvious genotype difference between Annong9912 and E28. Whether low or high starch content of starch content, the accumulation courses of amylopectin, amylose and total starch were well fitted to the logistic equation by relating starch contents against DAP. The simulation parameters revealed that the higher contents of amylopectin and amylose resulted from earlier initiating accumulation time and greater accumulation rate. And amylose, amylopectin and total starch accumulation rate of two wheat cultures were significantly and positively correlated with activities of SBE, SSS and GBSS, but amylose accumulation rate of E28 had no correlation with the activities of SBE. In addition, there were significant correlations among activities of SBE, SSS and GBSS in two wheat cultivars. We speculated that these enzymes proteins may have a coordinating action in starch biosynthesis within the amyloplast, operating as functional multiprotein complexes. And expression levels of enzyme genes demonstrated a single-peak curve, and 12-18 DAP reached their peaks and then began to drop, and all had high expression level in earlier stage of endosperm development, but in E28 were higher than in Annong9912. The GBSS-I transcripts on average were expressed over 60 times more than GBSS-II transcript in E28. SBE, SSS, DBE may control starch synthesis at the transcriptional level, and GBSS-I may control starch synthesis at the post transcriptional level. The expression level of DBE on average was lower than SS-1 and SBE-IIa genes, and similar to SS-III and SBE-IIb genes, but higher than GBSS-I and GBSS-II genes.
为了研究小麦籽粒不同发育阶段淀粉积累、酶活性变化以及基因表达水平及其相互关系，选用安农 9912 和 E28 为试验材料。在淀粉积累速率和灌浆速率方面，安农 9912 和 E28 之间存在明显的基因型差异。无论淀粉含量高还是低，支链淀粉、直链淀粉和总淀粉的积累过程都与 DAP 相对应，很好地符合逻辑斯蒂方程。模拟参数表明，支链淀粉和直链淀粉含量较高是由于起始积累时间较早，积累速率较大。两个小麦品种的直链淀粉、支链淀粉和总淀粉积累速率与 SBE、SSS 和 GBSS 的活性呈显著正相关，但 E28 的直链淀粉积累速率与 SBE 的活性无关。此外，两个小麦品种的 SBE、SSS 和 GBSS 活性之间存在显著相关性。我们推测这些酶蛋白可能在淀粉体中的淀粉生物合成中具有协调作用，作为功能多蛋白复合物发挥作用。酶基因的表达水平呈单峰曲线，12-18 DAP 达到峰值，然后开始下降，在胚乳发育的早期阶段均具有高表达水平，但在 E28 中表达水平高于安农 9912。E28 中 GBSS-I 转录本的表达水平平均比 GBSS-II 转录本高 60 倍以上。SBE、SSS、DBE 可能在转录水平上控制淀粉合成，GBSS-I 可能在转录后水平上控制淀粉合成。DBE 的表达水平平均低于 SS-1 和 SBE-IIa 基因，与 SS-III 和 SBE-IIb 基因相似，但高于 GBSS-I 和 GBSS-II 基因。
