青藏高原一年生野生大麦重要啤用品质性状调控特异基因及机理研究

Tibetan wild barleys have significant difference from each other in malting quality. In order to understand the regulatory mechanism of critial malting quality, the population for genome-wide association study (GWAS) analysis has been constructed with 200 Tibetan annal wild barleys and 50 elite international cultivars.The genetic lingkage map had been made by using high density molecular markers.By using this map, GWAS analysis will be conducted to select highly linked genetic loci and germplasms with possible novel genes according to the malting quality. A doubled haploid (DH) population will also be constructed by crossing an elite cultivar and Tibetan wild barley with possible advanced genes. The genetic linkage map will be constructed with high density DNA markers, and the related quantitative trait loci (QTLs) will be investigate. Critical linked genetic loci, marks and possible genetic pathway in malting-quality control will be obtained by comparing the QTL analysis results and GWAS analysis results.β-amylase activity is very important to malting quality. To finding out the β-amylase with high activity, the β-amylase alleles within GWAS population will be cloned and sequenced, and the genetic variation will be examined. To evaluation and obtain elite β-amylase genes, association analysis will be performed between the difference in base pair and the activity of β-amylase.After the special Tibetan wild germlasm is crossed with cultivated barley, the function of the elite β-amylase gene will be evaluated by the gene segregation and phenoyopte in the F2 population. The mechanism of β-amylase activity control will be also examined by GWAS and QTL study in the GWAS and QTL population, respectively.The elite DH lines and elite offsprings can be integrated into breeding program.This research will be helpful not only for elucidating the genetic mechanism of malting-quality control, and also for molecular breeding of malting barley with elite germplasm, perfect markers and novel alleles.

青藏高原一年生野生大麦不同种质的啤用品质存在显著差异。本研究以200份该野生种质和50份国内外优质啤用栽培品种为材料，构建全基因组关联研究（GWAS）分析群体，依据现有的高密度分子标记遗传图谱，进行GWAS分析；构建加倍单倍体(DH)群体，进行高密度分子标记，定位品质相关QTL；综合QTL和GWAS结果，缩小定位区间，鉴定品质调控的关键遗传位点，获得紧密连锁标记，揭示品质性状的遗传调控网络。鉴于β-淀粉酶活性对啤用品质的重要影响，将对QWAS群体进行β-淀粉酶基因测序和多态性分析，结合酶活进行关联分析，鉴定特异等位基因和种质，并通过杂交评价等位基因功能；对GWAS和QTL群体分别进行GWAS和QTL分析，明确β-淀粉酶活性调控关键遗传位点。优良的DH株系和淀粉酶特异基因杂交后代，纳入育种程序。研究结果可望为啤用大麦遗传改良奠定理论基础，并为优质育种提供特异种质、等位基因和分子标记。

近年来，我国啤用大麦50%依赖进口，啤酒生产受制于人。而我国独有的珍惜青藏高原一年生野生大麦（以下简称野生大麦）不同种质的啤用品质存在显著差异，可用于优良等位基因的挖掘、利用和相关遗传机理的解析。受国家自然基金项目资助以来，项目组以200份野生种质和50份国内外优质啤用栽培品种为材料，构建全基因组关联研究分析(GWAS)群体，并构建高密度分子标记遗传图谱，用于啤用品质的遗传分析。β-淀粉酶是决定糖化力的限速酶，对大麦啤用品质有至关重要的影响。因此，项目组成员进行了筛选了β-淀粉酶活性和热稳定性高的遗传材料，纳入了育种程序，并进行了相关遗传位点的鉴定，解析相关的遗传网络。通过研究发现，调控相关特性的基因，分别分布于1H-7H染色体上。而位于4H染色体上的关联分子标记, 密集、两年反复的出现在60-70 cM附近。在该区间内，我们发现β-淀粉酶结构基因位于此段DNA序列上。通过等位基因测序、依赖候补基因为基础的关联分析，我们发现该基因的等位基因较多、核苷酸变异较大，在基因的外显子部分，也存在较大的遗传变异。在外显子的变异中，包含了已被阐释的变异和首次发现的能引起氨基酸变化的变异。此项结果不仅为阐释相关遗传机理奠定基础，也为育种程序，提供有益的基因资源和材料基础。