小麦蜡质基因座位上SSR的多态性及其与直链淀粉含量的关系

SSR POLYMORPHISM ON THE WAXY GENE LOCUS AND THEIR RELATIONSHIP TO AMYLOSE CONTENT IN WHEAT

分析了蜡质基因(Wx)3′端的一个简单重复序列(SSR)(AT(AT)n AT)在32份小麦中的多态性及其与直链淀粉含量(AC)的关系。这些材料包括了山东省内的不同小麦品种,其AC含量差别较大。在扩增的小麦品种中均出现两条带,一条204bp(Wx-Dla)位于7DS染色体上,另一条225—346bp(Wx-Ala)位于7AS染色体上。也就是说在扩增的小麦品种中均存在Wx-Ala和Wx- Dla基因,并且较长的片段显示了长度多态性。分析表明AC与7D上这个SSR序列基因的多态性呈正相关,高AC小麦品种扩增的片段较长,电泳迁移率较小；相反,低AC小麦品种扩增的片段较短,迁移率较大,不同长度SSR品种间AC差异显著。虽然目前还不能确定这个SSR序列在直链淀粉合成中的直接功能,但SSR变异与AC之间的相关性可作为分子标记直接用于小麦品种改良。

Variation of one simple sequence repeat （SSR）（AT （AT）n AT）in the 3＇ waxy gene was analyzed in samples of 32 cuhivars, including different wheat Shandong region and representing a wide distribution range of amylose content （AC） wheat. In this study, we found two fragments were present in all cultivars, one of end of the cultivars in in cultivated 204bp, the expected size, and one of 225-346bp. 204bp fragment located on the chromosome 7DS, while 225-346bp fragment located on the chromosome 7AS. That is, Wx-Ala gene and Wx-Dla gene present in all wheat lines, but the larger fragment showed length polymorphism. The result showed that the amylose level is highly positive correlated with the length of the polymorphic SSR. Amplified fragment is long in high AC cultivars and electrophoresis migration rate is small, while the fragment is short in low AC cuhivars and electrophoresis migration rate is large. AC is highly diverse among different lines with the various SSR genotypes. Although the SSR variation did not seem to have obvious function in the synthesis of the starch synthase encoded by the waxy gene, the correlation between the SSR and AC level could be used as molecular marker for quality improvement in wheat programs.