西南麦区骨干亲本川麦42重要基因组区段的确定及其对衍生品种的遗传贡献

Identification of important genomic regions for foundational parent Chuanmai 42 of southwest wheat-growing zone and their genetic contribution

【目的】川麦42是利用人工合成六倍体小麦选育出的高产、广适的优异小麦品种,是西南麦区重要的骨干亲本,本研究通过明确川麦42重要基因组区段及其对衍生品种的遗传贡献,为西南麦区突破性品种培育提供分子设计依据。【方法】利用170个SSR和2268个DArT标记分析川麦42遗传组分在7个衍生品种中的分布与传递情况;根据已构建的遗传图谱和定位到的产量性状QTL,明确川麦42遗传组分对各个衍生品种的遗传贡献。【结果】川麦42遗传组分在7个一代衍生品种中分布与传递频率不同,其中川麦56、川麦58、川麦64、川麦104、川麦90和川麦91继承了50%以上的川麦42的遗传组分,平均为64%,高于理论值,而川麦92则低于25%。17条小麦染色体上的92个等位位点在川麦42衍生品种中具有较高的分布频率,得到稳定传递;对比已构建的川麦42遗传连锁图谱及其定位到的QTLs,发现位于2A、2B、4A、4D、5B、5D、5A、6D、7A和7D染色体上11个基因组区段与重要农艺性状QTL紧密连锁,其中4A、4D、5B、5D和7D染色体上川麦42单倍型可提高衍生品种的穗粒数、千粒重和小区产量;位于5B染色体Xgwm234~Xgwm371区段携带千粒重QTL,川麦42单倍型最高可增加千粒重2.21 g;位于4D、5D和7D染色体区段携带小区产量QTL,川麦42单倍型最高增产率分别为8.92%、6.33%、4.79%。【结论】携带产量性状增效QTL并且在衍生品种中能够高频传递的基因组区段是川麦42能够成为西南麦区骨干亲本的重要遗传基础,川麦42重要基因组区段的确定为西南麦区小麦骨干亲本选择及突破性品种的培育提供了重要的理论参考。

[Objective]Chuanmai 42,an elite wheat cultivar with high-yield potential and good adaptability,is derived from synthetic hexa-ploid wheat and has been widely used in wheat breeding program in Southwest China.By identifying the important genomic segments of Chuanmai 42 and its genetic contributions to the derivatives,the study provided molecular design basis for the breeding of breakthrough vari-eties in southwest wheat region.[Method]Chuanmai 42 and its seven derived cultivars were genotyped using 170 SSR markers and 2268 DArT markers for analyzing the distribution of Chuanm 42's genomic components and their transmissibility in Chuanmai 42-derived culti-vars.Based on constructed genetic map and the mapped QTLs for yield traits,the genetic contribution of Chuanmai 42 genomic components to seven derived varieties was identified.[Result]The distribution frequency of Chuanmai 42's genetic components were alternative in its derived cultivars.Among seven Chuanmai 42-derived 1t generation cultivars,Chuanmai 56,Chuanmai 58,Chuanmai 64,Chuanmai 104,Chuanmai 90 and Chuanmai 91 inherited more than 50%genetic components of their breeding parent Chuanmai 42,and Chuanmai 92 was less than 25%.A total of 92 introgression loci from Chuanmai 42 involved on 17 chromosomes were distributed highly among seven derived cultivars.Based on a linkage map from Chuanmai 42 containing 148 SSR and 644 DArT markers and previous-identified QTLs,eleven ge-nomic regions were found to carry QTLs for important agronomic traits on chromosomes 2A,2B,4A,4D,5B,5D,5A,6D,7A and 7D.The high-frequency introgression loci from Chuanmai 42 on chromosomes 4A,4D,5B,5D and 7D were associated with increasing grain number per spike,thousand-kernel weight and grain yield.Especially,the region of Xgwm234-Xgwm371 on chromosome 5B harbored a ma-jor QTLfor thousand-kernel weight,and Chuanmai 42 haplotype increased the thousand-kernel weight by 2.21 g.The genomic regions on chromosome 4D,5D and 7D carried QTLs for increasing grain yield,with the Chuanmai 42 haplotype increasing rate of grain yield by 8.92%,6.33%,4.79%,respectively.[Conclusion]The chromosomal regions of high-frequency transmission harboring QTLs for yield-re-lated traits are deduced to be the genetic basis of Chuanmai 42 serving as a foundational breeding parent.The identification of important ge-nomic regions in Chuanmai 42 provides an important theoretical reference for breeding breakthrough wheat varieties and screening foundation-al parents in the southwest China.