水旱稻根基粗、千粒重主效QTL近等基因系的构建及鉴评

近等基因系的选育是分子遗传图谱构建、数量性状基因定位及分子标记辅助育种的重要基础之一。本文利用分子标记辅助目标性状QTL前景选择及恢复轮回亲本基因组的背景选择，再结合表型选择获得了定位在水稻4号、6号染色体上根基粗、千粒重2个主效QTL的近等基因系。其中有9个系入选旱田根基粗主效QTL brt4.1的近等基因系，根基粗的表型值为1.07～1.16mm，较轮回亲本越富提高6.11％～15.18％，平均遗传背景恢复率达97.22％；千粒重主效QTL的近等基因系有11个系入选，千粒重的表型值为21.25～26.25g，较轮回亲本越富的增幅为7.05％～32.16％，平均遗传背景恢复率为95.97％。另外，本文还就分子标记辅助近等基因系选育中背景选择标记数的确定、基于QTL-NILs的基因克隆等进行了讨论。

Construction and Evaluation of the Near-isogenic Lines for Major QTLs of Basal Root Thickness and 1000-grain-weight in Lowland and Upland Rice

The development of near-isogenic lines (NILs) is one of the important foundations for the establishment of molecular linkage map, the mapping of quantitative trait loci (QTL) and molecular marker-assisted selecton (MAS). In the present study, NILs for two major QTLs of basal root thickness(BRT) and 1000-grain-weight(TGW) were obtained through the foreground selection for target QTL, the background selection for the genome of the recurrent parent of 3 backcross populations( BC1F1、BC2F1、BC3F1) and phenotypic selection for the population of BC3F2. They were 9 of BRT QTL-NILs with BRT ranges of 1.07~1.16mm, over the recurrent parent by 6.11%~15.18% and an average recovering ratio of genetic background (RRGB)of 97.22%; 11 NILs of 1000-grain-weight (TGW) QTL with ranges of 21.25～26.25g, over the recurrent parent by 7.05％～32.16％ and 95.97% of RRGB. The number of molecular markers for background selection in the development of NILs and QTL cloning were also discussed.