Identification of a candidate gene for a QTL for spikelet number per spike on wheat chromosome arm 7AL by high-resolution genetic mapping
Identification of a candidate gene for a QTL for spikelet number per spike on wheat chromosome arm 7AL by high-resolution genetic mapping
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DOI：
10.1007/s00122-019-03382-5
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发表时间：
2019-09-01
影响因子：
5.4
通讯作者：
Dubcovsky, Jorge
中科院分区：
文献类型：
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作者：
Kuzay, Saarah;Xu, Yunfeng;Dubcovsky, Jorge
关键信息高分辨率遗传图谱结合单倍型分析，确定水稻基因APO1的小麦直系同源基因是影响每穗颖花数的7AL基因座的最佳候选基因。更好地了解控制小麦产量构成差异的基因，可以加快满足未来粮食需求所需的改良。在本研究中，我们在小麦染色体臂7AL上发现了一个控制每穗颖花数(SNS)的数量性状基因(QTL)。我们利用来自两个杂交组合的大型异质自交系(>；10,000株)将7AL QTL定位到一个87kb的区域(674,019,191-674,106,327 bp，RefSeq v1.0)，其中包含两个完整基因和两个部分基因。在该区域，我们发现了三种主要的单倍型，分别命名为H1、H2和H3。在H_1×H_2和H_2×H_3分离群体中，H_2单倍型贡献了高SNS等位基因。祖先的H3单倍型在野生二粒小麦中常见(48%)，在栽培小麦中很少(1%)。相比之下，H1和H2单倍型分别在现代栽培硬粒小麦和普通小麦中占优势。在4个候选基因中，只有TraesCS7A02G481600表现出区别于其他两个单倍型的非同义多态。该基因命名为小麦APO1(WAPO1)，是水稻异常穗部组织1(APO1)基因的直系同源基因，影响小穗数。综上所述，高分辨率的遗传图谱，不同作图群体的多态与SNS差异的关联，以及同源基因在其他草种中的已知作用，表明WaPo-A1是候选基因区域中最有可能的7AL SNS QTL的候选基因。
Key message A high-resolution genetic map combined with haplotype analyses identified a wheat ortholog of rice gene APO1 as the best candidate gene for a 7AL locus affecting spikelet number per spike. A better understanding of the genes controlling differences in wheat grain yield components can accelerate the improvements required to satisfy future food demands. In this study, we identified a promising candidate gene underlying a quantitative trait locus (QTL) on wheat chromosome arm 7AL regulating spikelet number per spike (SNS). We used large heterogeneous inbred families ( > 10,000 plants) from two crosses to map the 7AL QTL to an 87-kb region (674,019,191-674,106,327 bp, RefSeq v1.0) containing two complete and two partial genes. In this region, we found three major haplotypes that were designated as H1, H2 and H3. The H2 haplotype contributed the high-SNS allele in both H1 x H2 and H2 x H3 segregating populations. The ancestral H3 haplotype is frequent in wild emmer (48%) but rare ( 1%) in cultivated wheats. By contrast, the H1 and H2 haplotypes became predominant in modern cultivated durum and common wheat, respectively. Among the four candidate genes, only TraesCS7A02G481600 showed a non-synonymous polymorphism that differentiated H2 from the other two haplotypes. This gene, designated here as WHEAT ORTHOLOG OF APO1 (WAPO1), is an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1), which affects spikelet number. Taken together, the high-resolution genetic map, the association between polymorphisms in the different mapping populations with differences in SNS, and the known role of orthologous genes in other grass species suggest that WAPO-A1 is the most likely candidate gene for the 7AL SNS QTL among the four genes identified in the candidate gene region.