利用高密度SNP芯片定位玉米雄穗分枝数QTL

QTL Mapping of the Tassel Branch Number Using High-density SNP Array in Maize

玉米雄穗分枝数是影响玉米产量的重要因素之一,研究控制玉米雄穗分枝数的QTL位点对玉米品种改良、分子辅助育种具有重要意义。本研究利用京科968的双亲京724和京92构建BC1F1群体,以Maize6H-60K高质量高密度SNP芯片鉴定群体基因型,获得28910个高质量多态性SNP,构建了包含2737个BIN标记的高密度遗传图谱,各染色体BIN标记数在145~512个之间,BIN标记平均遗传距离为0.56 cM。2021年将亲本及727个单株种植在北京,调查雄穗分枝数。采用QTL IciMappingV4.2的完备区间作图法进行雄穗分枝数QTL检测及定位,共检测到6个QTL,分别位于第2、5、6、7、8和9染色体,QTL的LOD值范围为3.18~11.08,揭示1.58%~5.59%的表型变异。通过物理位置比对,6个QTL中有4个与前人定位在相同区域,qTBN6和qTBN7尚未见报道。其中qTBN6的LOD为6.73,增效等位基因来自京724,具有负的加性效应,作用为减少雄穗分枝数。本研究为克隆调控雄穗分枝数功能基因奠定了基础。

The tassel branch number of maize is one of the important factors affecting the yield production.Unlocking the QTL loci to control the tassel branch number of maize is of great significance for maize variety improvement and molecular assisted breeding.In this study,the individuals of a BC1F1 population derived from the parents Jing724 and Jing92 of Jingke968 were genotyped using high-throughput high-quality SNP array Maize6H-60K.By taking use of 28910 polymorphic SNPs,a high density genetic map containing 2737 BIN markers was constructed.The number of BIN markers on each chromosome ranged from 145 to 512,and the average genetic distance was 0.56 cM.Both parents and 727 offspring lines were planted in Beijing in 2021 to investigate the tassel branch number,followed by QTL mapping using Inclusive Composite Interval Mapping(ICIM)in software QTLIciMappingV4.2.A total of 6 QTL were detected,located on chromosomes 2,5,6,7,8 and 9,respectively.The LOD score of QTL ranged from 3.18 to 11.08,revealing 1.58%to 5.59%phenotypic variation.While four QTL were located in the same or adjacent area as previously reported,two novel QTL qTBN6 and qTBN7 have been revealed.The LOD of qTBN6 was 6.73,and the synergistic allele derived from Jing724,with a negative additive effect to reduce the tassel branch number.Collectively,this study laid a foundation for future isolating the functional genes that regulate the tassel branch number in maize.