花生大果种质D893产量相关荚果性状QTL qPwwt-A08-1定位与候选基因分析

Peanut (Arachis hypogaea L.) is a major economic crop , and as well, an important resource of edible oil production in China. Pod weight and kernel rate (ratio of the seed weight to the total pod weight) are the most impotant factors for peanut yield. Identifying for the quantitative trait loci ( QTLs) and functional genes assoeiated with pod weight and kernel rate, and analysis its effects for improving yield, is the basis of the high yield molecular breeding in peanut. Based on the initial QTL mapping for yield-related pod traits using 142 recombinant inbred lines (RILs) developed from “79266×D893” over six environments, one major QTL assoeiated with pod weight, pod width and thickness of pod shell, which stable expressed in five environments, designated as qPwwt-A08-1, located a 6.98 Mbp region of linkage group A08, flanked by A08：11867653 bp -18849670 bp. In this project, positional specific markers will be developed in the QTL target interval by using the sequenees information of A08 of Arachis duranensis（http://peanut base.org）and the integrated consensus map in peanut(http://marker.kazusa.or.jp). In addition, another positional specific markers will be developed using next-generation double-digest restriction-site-associated DNA sequencing (ddRADseq) with two parents and lines of RIL population. RIL population and F2:3 population of “79266×D893”, and a nature population of cultivated peanut accessions will be used to carried out fine mapping for qPwwt-A08-1. Markers closely related to pod yield traits and functional genes assoeiated with pod weight and kernel rate, will be identified. The project's goal is revealing the mechanism of regulation of pod weight and kernel rate by qPwwt-A08-1, and providing molecular markers, gene resources, and new germplasms, for high yield molecular breeding in peanut.

花生是我国重要的油料与经济作物。鉴定和挖掘产量相关荚果性状的主效QTL和功能基因、开发分子标记，是实现花生高产分子育种的基础。本项目以前期创制的大果种质D893为研究载体，在进行了荚果大小和果壳厚度QTL初步定位的基础上，借助花生野生种基因组信息（http://peanut base.org），利用“79266×D893 ”的RIL群体、F2:3群体、次级F2:3群体以及156份种质资源组成的自然群体，对A08连锁群上控制花生果壳厚度、果宽、单果重的环境钝感主效QTL qPwwt-A08-1进行精细定位，开发紧密连锁的分子标记，筛选推测控制荚果性状的候选基因，比较亲本和群体极端性状家系的候选基因序列特征和表达差异，进行基因功能解析，以期探明调控果壳厚度和荚果大小性状的分子机理和生化途径，为花生高产分子育种提供必要的理论和物质基础。

项目利用“79266×D893 ”RIL群体构建的SSR标记遗传图谱结合7个种植环境的表型数据定位到A08连锁群上控制果宽、果壳厚度、单果重的环境钝感主效QTL qPwwt-A08-1，标记区间遗传距离为4.5cM。基于极端混池(BSA)全基因组重测序，利用包含1020个单株的F2群体，在A07连锁群和A08连锁群均获得单果重QTL显著关联区域，将A07关联区域的8个SNP和A08关联区域的18个SNP成功转换成KASP标记，分析RIL群体家系和F2群体单株的基因型，完成QTL初定位区间的标记加密，将主效QTL qPwwt-A08-1的标记区间缩短为1.8cM、对应DNA长度为1.16Mb。A07连锁群上检测到另一个荚果性状主效QTL聚集区域，其中果宽QPW-2标记区间DNA长147.1Kb，果壳厚度QPST-2标记区间DNA长63.5Kb，单果重QSPW-2标记区间DNA长85.8Kb。在上述标记区间预测到Arahy.BM3759、Arahy.PUN1W8 、Arahy.17357K 和Arahy.IAUU74共4个功能基因，分别编码ATP酶家族蛋白、醛酮还原酶、组氨酸激酶2以及与细胞周期相关的蛋白。研究结果为分子标记辅助选择提供了紧密连锁的KASP标记，为挖掘鉴定荚果大小及果壳厚度的关键基因提供了支撑。