甘蓝型油菜特大籽粒千粒重QTL精细定位及相关同源基因分析

Thousand seeds weight (TSW) as one of the three direct components (silique per plant, seeds persilique and seeds weight) of plant grain yield is positively correlated with plant productivity. Although, many studies focused on the QTLs mapping of TSW-trait in oilseed rape, there was no definite results on the geneticmechanism of seed weight. From investigate the reasons, except the aspects of the difference of genetic background in materials used in studies, the relatively minor differences of TSW-trait in parents and environmental impact on the TSW-trait, the low-density DNA molecular markers in QTL mapping is one of the very important restraint factor. Based on the results of research financed by National Natural Science Foundation of China (grant number 30860147), F1DH populations as primary mapping population derived from cross of large seed material 050097(TSW, 7.22g) and small seed material 050133 were employed to construct high-density markers linkages map by using SNPs, SSR and IP markers and detect QTL for TSW-trait; 050133 as recipient parent and 050097 as donor parent were used to construct advanced backcross population to fine mapping the gene for TSW-trait. This study will lay the groundwork for breeding of high TSW-value variety and cloning the related homologousgenes on controlling TSW trait in Brassica napus L.

千粒重是油菜产量构成的主要因素之一；对千粒重主效QTLs已进行了一系列研究，均未能获得明确、统一的结果。究其原因，除所用的亲本遗传背景不同、所获标记的数量较少及千粒重性状易受环境影响等因素外，主要因素是亲本间千粒重差异较小。本项目研究拟在已完成的国家地区基金（30860147）研究基础上，利用甘蓝型油菜特大籽粒材料050097（千粒重7.22g）与小籽粒亲本050133（千粒重2.80g）F1 DH 群体作为初级作图群体，利用从国际协作组获得的60K甘蓝型油菜infinium芯片技术为主，以SSR为锚定标记，辅以源于拟南芥籽粒发育基因的IP标记，构建甘蓝型油菜高千粒重性状高密度遗传图谱；克隆并分析落入主效QTL区间IP标记所对应的大、小籽粒油菜同源基因；以小籽粒材料为轮回亲本构建高世代回交群体为次级作图群体，对控制千粒重的主效位点进行精细定位；为高千粒重品种选育、主效基因克隆研究奠定基础。

千粒重是产量构成的重要因素之一。本研究利用大籽粒050097（千粒重7.22g）和小籽粒材料050133（千粒重2.38g）构建的F1DH群体，应用甘蓝型油菜60K Illumina芯片技术，进行SNP芯片分析，构建了总长为2260.90 cM，包含2848个SNP标记、78对SSR标记，结合2年6个试验点次的千粒重数据进行QTL扫描，获得31个与千粒重性状相关的位点，其中位于A9连锁群的tsw-BN9-1位点在6个环境下均被检测到，该位点最高可解释57%的千粒重遗传变异，加性效应值为0.644g，LOD值高达42.6。利用BC6回交群体构建了大小籽粒极端DNA混合池，再进行SNP分析，将该主效位点进一步定位于甘蓝型油菜A9染色体3M与白菜A9染色体5M区间内，分别包含210和440个基因，初步实现了千粒重主效位点tsw-BN9-1位点精细定位。同时，对大小籽粒材料胚珠三个发育时期进行转录组测序研究，累计获得了3690个差异表达基因，并明确了目标基因区间基因的时空表达情况。该研究有助于精细定位千粒重主效QTL位点及分子标记辅助高千粒重育种。