Heading time is one of the most important agronomic traits in wheat, as it largely affects both adaptation to different agro-ecological conditions and yield potential. Identification of genes underlying the regulation of wheat heading and the development of diagnostic markers could facilitate our understanding of genetic control of this process. In this study, we developed 400 recombinant inbred lines (RILs) by crossing a γ-ray-induced early heading mutant (eh1) with the late heading cultivar, Lunxuan987. Bulked Segregant Analysis (BSA) of both RNA and DNA pools consisting of various RILs detected a quantitative trait loci (QTL) for heading date located on chromosomes 5B, and further genetic linkage analysis limited the QTL to a 3.31 cM region. We then identified a large deletion in the first intron of the vernalization gene VRN-B1 in eh1, and showed it was associated with the heading phenotype in the RIL population. However, it is not the mutation loci that resulted in early heading phonotype in the mutant compared to that of wildtype. RNA-seq analysis suggested that Vrn-B3 and several newly discovered genes, including beta-amylase 1 (BMY1) and anther-specific protein (RTS), were highly expressed in both the mutant and early heading pool with the dominant Vrn-B1 genotype compared to that of Lunxuan987 and late heading pool. Enrichment analysis of differentially expressed genes (DEGs) identified several key pathways previously reported to be associated with flowering, including fatty acid elongation, starch and sucrose metabolism, and flavonoid biosynthesis. The development of new markers for Vrn-B1 in this study supplies an alternative solution for marker-assisted breeding to optimize heading time in wheat and the DEGs analysis provides basic information for VRN-B1 regulation study.

中文翻译：

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使用小麦的RIL群体通过QTL定位鉴定负责抽穗日期变化的春化基因VRN-B1。

抽穗时间是小麦最重要的农艺性状之一，因为它在很大程度上影响对不同农业生态条件的适应性和单产潜力。鉴定小麦抽穗调控基础的基因和开发诊断标记可以促进我们对这一过程的遗传控制的了解。在这项研究中，我们通过将γ射线诱导的早抽穗突变体（eh1）与晚抽穗品种Lunxuan987杂交，开发了400个重组自交系（RIL）。由各种RIL组成的RNA和DNA池的大体积分离分析（BSA）检测到位于5B染色体上的抽穗期的数量性状基因座（QTL），进一步的遗传连锁分析将QTL限制在3.31 cM区域。然后，我们在eh1中的春化基因VRN-B1的第一个内含子中发现了一个大缺失，并表明它与RIL群体中的标题表型有关。但是，与野生型相比，突变位点不是导致突变体早期抽穗型的原因。RNA-seq分析表明，Vrn-B3和几个新发现的基因，包括β-淀粉酶1（BMY1）和花药特异性蛋白（RTS），在具有显性Vrn-B1基因型的突变体和早期抽穗池中均高表达相较于Lunxuan987和后期抽奖池。差异表达基因（DEG）的富集分析确定了先前报道的与开花相关的几种关键途径，包括脂肪酸延伸，淀粉和蔗糖代谢以及类黄酮的生物合成。