中文摘要：

粒重是影响小麦产量的主要因素之一。QGw.nau-5A是一个从我国小麦骨干亲本南大2419中鉴定的粒重主效QTL。为评价该QTL不同等位基因对粒重的效应及在育种中的应用潜力,利用分子标记辅助选择技术,分别将南大2419和早洋麦的QGw.nau-5A区段导入望水白和川麦42,构建了不同背景的近等基因系,并比较了不同背景下粒重QTL的效应。结果表明,QGw.nau-5A能在不同背景下显著提高小麦粒重,与轮回亲本相比,近等基因系的百粒重显著增加0.2~0.6g。QGw.nau-5A等位变异对粒重的贡献存在差异,与川麦42的等位变异相比,南大2419和早洋麦的等位变异均能增加粒重,但后者效应更大。

英文摘要：

Grain weight,a quantitative trait controlled by multiple genes,is a major yield component in wheat. Understanding the genetic control of this trait could help to improve breeding efficiency for grain weight. QGw. nau-SA ,a major quantitative trait locus（QTL） associated with grain weight,was previously identified in a recombinant inbred line mapping population derived from the cross between the Chinese elite cultivar Nanda 2419 and landrace Wangshuibai. To further evaluate the effects of dif- ferent allelic variations in germplasm collection and in turn their breeding potential, in this study a number of near-isogenic lines（NILs） of QGw. nau-SA were developed through marker-assisted selec- tion,with the Nanda 2419 and Early Premium（an American cultivar used widely as a founder parent in breeding） as donor parents,and Wangshuibai and cultivar Chuanmai 42 as the recurrent parents during backcrossing. The results showed that QGw. nau-5A indeed worked in different genetic backgrounds and different alleles contributed differently to grain weight. That is, the NILs carrying the alleles from Nanda 2419 and Early Premium constantly produced significantly larger grains（0.2--0.6 g per hun- dred grain） than the respective recurrent parents did：in the background of landrace Wangshuibai,the grain weight was increased by 9. 11% while in the Chuanmai 42 background,introduction of Nanda 2419 and Early Premium alleles increased grain weight by 4.24% and 8.73% ,respectively. The Nanda 2419 and Early Premium alleles therefore performed better than those of Chuanmai 42 and Wang-shuibai. And the Early Premium allele performed better than that of Nanda 2419.