基于SNP高密度遗传连锁图谱的玉米南方锈病抗性QTL定位

QTL mapping for resistance to southern corn rust based on high-density SNP genetic linkage map

  • 摘要:目的】通过高抗玉米南方锈病自交系抗性QTL定位,为开展玉米分子标记辅助育种和抗病性状的遗传调控机制研究打下基础。【方法】以高抗玉米南方锈病自交系S311和高感玉米南方锈病自交系HY813杂交构建F2代群体,利用10K SNP芯片对F2代群体的186个单株进行基因分型后,构建高密度遗传连锁图谱。将该遗传连锁图谱与表型数据相结合,采用复合区间作图法(CIM)和全基因组复合区间作图法(GCIM)确定玉米南方锈病抗性QTL位置和效应。【结果】F2代群体的玉米南方锈病抗性表现更偏向于父本S311;病害等级为1~9级,偏度和峰度均在-1.00~1.00,符合数量性状的分布特征。利用3103个SNP标记构建遗传连锁图谱,该图谱总长度为3607.39 cM,标记之间的平均遗传距离为1.16 cM。利用CIM检测到4个QTL,分别位于1号染色体和3号染色体上,其中位于3号染色体上QTL位点qSCR3-1qSCR3-2的LOD值较高,表型变异解释率分别为25.6%和10.0%。采用GCIM在3号染色体上检测到2个QTL位点qSCR3-1qSCR3-2,表型变异解释分别为64.4%和16.5%。在2种方法共同鉴定到QTL位点上筛选到4个与抗病相关基因Zm00001d042214Zm00001d041994Zm00001d042013Zm00001d042051。接种病原菌后,Zm00001d042214Zm00001d041994Zm00001d042013Zm00001d042051基因在S311叶片中的相对表达量均较接种前(CK)极显著升高(P<0.0001);而HY813接种病原菌后,Zm00001d042214基因在叶片中的相对表达量与接种前无显著变化(P>0.05)、Zm00001d042013基因在叶片中的相对表达量较CK极显著升高(P<0.01)、Zm00001d041994Zm00001d042051基因在叶片中的相对表达量均较CK极显著升高(P<0.0001)。【结论】在自交系S311中定位到2个玉米南方锈病抗性主效QTL位点qSCR3-1qSCR3-2,在QTL区间筛选到Zm00001d042214Zm00001d041994Zm00001d042013Zm00001d042051等4个抗玉米南方锈病的候选基因。

     

    Abstract:Objective】This study aimed to map quantitative trait loci (QTL) for resistance to southern corn rust using a highly resistant maize inbred line, providing basis for elucidating molecular marker-assisted breeding and genetic regulation mechanisms of disease resistance of maize.【Method】The F2 population derived from a cross between the highly resistant inbred line S311 and the highly susceptible inbred line HY813, comprising 186 individuals, were genotyped using a 10K SNP chip to construct a high-density genetic linkage map. By integrating the genetic linkage map with phenotypic data,the composite interval mapping (CIM) and genome-wide composite interval mapping (GCIM) were employed to determine the positions and effects of QTLs.【Result】The resistance to southern corn rust in the F2 population tended to resemble that of the paternal parent S311. The disease severity was rated from 1 to 9, with skewness and kurtosis both between -1.00 and 1.00, which was consistent with the distribution characteristics of quantitative traits. A total of 3103 single nucleotide polymorphism (SNP) markers were used to construct a genetic linkage map whose total length was 3607.39 cM, and average genetic distance between markers was 1.16 cM. A total of 4 QTLs were detected using CIM, located on chromosomes 1 and 3, among which the QTL loci qSCR3-1 and qSCR3-2 on chromosome 3 had higher (logarithm of odds LOD) values,explaining 25.6% and 10.0% of phenotypic variation respectively. A total of two QTL loci, namely qSCR3-1 and qSCR3-2 on chromosome 3, were detected using GCIM, explaining 64.4% and 16.5% of phenotypic variation respectively. A total of four candidate genes associated with disease resistance, namely Zm00001d042214Zm00001d041994Zm00001d042013, and Zm00001d042051, were identified within the QTL loci commonly detected by both methods. After pathogen inoculation, the relative expression of Zm00001d042214Zm00001d041994Zm00001d042013, and Zm00001d042051 in leaves of S311 was all extremely significantly increased compared with those before inoculation (CK) (P<0.0001). In HY813 after pathogen inoculation, however, the relative expression of Zm00001d042214 showed no significant change (P>0.05), while Zm00001d042013 was extremely significantly up-regulated compared with CK (P<0.01), and both Zm00001d041994 and Zm00001d042051 were extremely significantly up-regulated compared with CK (P<0.0001).【Conclusion】In the inbred line S311, two major QTL loci (qSCR3-1 and qSCR3-2) for resistance to southern corn rust are mapped, and four candidate genes related to resistance to southern corn rust are screened within the QTL intervals,namely Zm00001d042214Zm00001d041994Zm00001d042013, and Zm00001d042051.

     

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