半冬性春化基因与黄淮冬麦区小麦品种抗寒性关系研究

Freezing damage of wheat cultivars at the seedling stage occurs frequently in YHWZ, which is one of the most important abiotic stresses that limits wheat production in this region. The improvement of winter hardiness is the solution to solve this problem. The reliable selection method is not available for improving the winter hardiness of cultivars because the genetic mechanism of this trait is unclear. Therefore, understanding the genetic mechanism of the winter hardiness and developing an accurate and convenient selection method are in great need. The allelic variation Vrn-D1b at locus Vrn-D1 was shown to be associated with the facultative growth habit, which is the predominant type among the cultivars grown in YHWZ. A relationship between the winter hardiness and vernalization genes was shown in previous studies. If the relationship between the allelic variation at locus Vrn-D1 and the winter hardiness can be verified, it will be possible to use the locus-linked molecular markers in marker-assisted selection (MAS) for winter hardiness. In this project, the relationship between Vrn-D1b and winter hardiness and other possible loci associated with the winter hardiness will be identified using a residual heterozygous line (RHL)-derived population and a recombinant inbred lines (RILs) from the cross Shi 4185 (Vrn-D1b) × Shijiazhuang 8 (vrn-D1) based on the phenotypic evluations under multiple years and environments and the controlled conditions, in combination with genotypic analysis by the wheat 660K SNP chip. The objectives of this study are to unravel the genetic mechanism and establish the MAS technique for improvement of wheat winter hardiness at the seedling stage. The outcomes of this study will provide a powerful technical support for developing wheat cultivars with winter hardiness.

近年来，黄淮冬麦区小麦品种苗期冻害频发，已成为影响该麦区小麦生产的主要自然灾害之一。提高品种抗寒性是解决该问题的关键。遗憾的是当前缺乏可靠的选择技术来加快抗寒品种选育，究其原因是品种抗寒遗传机制不明。半冬性品种是黄淮冬麦区种植的主要类型，我们发现新等位变异Vrn-D1b与半冬性密切相关。已有研究表明抗寒性与春化特性存在一定关系。如果能明确Vrn-D1b与抗寒性的关系，就可利用此分子标记进行抗寒辅助选择。本研究利用石4185×石家庄8号F6 RIL构建的剩余杂合系（residual heterozygous line）衍生群体和F8 RIL群体，通过多年多点抗寒性鉴定，结合Vrn-D1位点和RILs 660K SNP芯片基因型分析，阐明Vrn-D1b与抗寒性关系，并发掘与抗寒有关新基因/QTL，探究小麦苗期抗寒的遗传机制。同时，建立黄淮冬麦区小麦抗寒标记辅助选择技术，为抗寒育种提供技术支持。

冻害是影响我国冬小麦安全生产和国家粮食安全的重要自然灾害之一。近年来黄淮冬麦区小麦品种苗期冻害频发，已严重影响该麦区小麦生产，所以提高小麦品种抗寒性是解决问题的关键之一。半冬性品种是黄淮冬麦区种植的主要类型，前期我们研究发现Vrn-D1位点新等位变异Vrn-D1b与半冬性密切相关。已有报道小麦春化特性与品种抗寒性存在一定关系。因此，明确Vrn-D1b与抗寒性的关系以及发掘影响抗寒性的QTL就可利用分子标记进行黄淮冬麦区小麦品种抗寒性标记辅助育种。本研究通过对石4185/石家庄8号F8 RIL群体、F6 RIL构建的剩余杂合系（RHL）群体、石家庄8号/石麦12 F2、F2:3群体和自然群体多年多点抗寒性表型鉴定结合Vrn-D1位点基因型数据，明确了Vrn-D1位点不同等位变异与抗寒性的关系，结果发现Vrn-D1位点3个等位变异抗寒性从强到弱依次为：vrn-D1>Vrn-D1b>Vrn-D1a。抗寒基因表达分析发现，抗寒品种石家庄8号的基因表达量明显高于石4185和石麦12，而石4185的表达量高于石麦12，抗寒基因的表达量和品种的抗寒性一致。同时，利用多年、多点表型数据和小麦55K SNP数据，在5A染色体上定位一个主效的控制小麦死苗率和死茎率的QTL Qwksr-5A，该位点在多个环境中稳定表达，解释表型变异从6.14%到16.45%。利用该位点侧翼SNP信息，开发了一个紧密连锁的KASP标记，并在自然群体和遗传群体中得到验证，为后续该QTL的精细定位、克隆奠定了基础。通过本研究明确了Vrn-D1位点不同等位变异与抗寒性的关系，同时基于新QTL开发的KASP标记和用于区分Vrn-D1不同等位变异的标记可用于抗寒性分子标记辅助育种。