玉米穗粒腐病抗病QTLqRfv1的精细定位和分离

Maize plays an important role in the national food security as an important food , animal feed and raw material for industrial use with 3,200 ha in China. Fusarium verticillioides ear rot,one of the prevalent diseases in the world, causes serious yield loss and contaminated kernels with mycotoxin potentially threatening animal and human health. Deploying resistant varieties is one of the best approachoes to reduce the damage of ear rot, depending on the discovery and utilization of the efficient and stable resistant QTLs for F.verticillioides ear rot. BT-1, a maize inbred line was identified as an elite line with resistance to F.verticillioides ear rot in previous study. A major QTL qRfv1,on chromosome 4 (bin 4.05-4.06) with the largest effect explaining 10.2%～24.67% additive phenotypic variance for F. verticillioides ear rot resistance, was identified using F2:3 and RIL populations derived from the combinations of the resistant inbred line BT-1 respectively crossed with susceptible line N6, Xi502 and Xiongzhang. In this proposal, the near-isogenic lines were developed by converting the QTL region on chromosome 4 of the resistant parent BT-1 to susceptible parents N6 and Xi502, and the QTL effect of resistance to F. verticillioides was validated in the three NIL populations. Another Two large NIL populations with 20,000 families and a BAC-based DNA library from the resistant line BT-1 will be constructed for map-based cloning of it. The gene will be mapped to a 100 Kb region, and the target clones will be sequenced, then the candidated genes will be identified. The sequences of the candidated genes will be compared between the resistant and susceptible parental lines, their functions will be analyzed by the association analysis for further exploration of resistance mechanism and marker-assisted selection.

玉米穗粒腐病是世界上普遍发生、危害严重的一种真菌性病害，不仅直接影响了玉米的产量和品质，而且其病原菌产生的真菌毒素，给人、畜安全造成了严重威胁，选育抗病品种的成效取决于抗病遗传规律的了解。课题组选育和鉴定出1份优异抗源BT-1，并利用多亲本、多群体鉴定出１个主效ＱＴＬqRfv1，具有年份、地点、播期等多环境的稳定性，回交育种结合标记辅助选择，选育出近等基因系群体并对qRfv1进行了验证。在此基础上进一步构建大分离群体NILF2，利用目标区域已有的分子标记和基于基因组测序等信息开发的分子标记筛选交换单株，通过后代测试和多环境鉴定确定单株表型，逐步逼近抗病位点，利用qRfv1紧密连锁的分子标记筛选ＢＴ-１的ＢＡＣ文库，对目标BAC克隆进行测序并进行生物信息学分析，预测候选基因，进一步进行候选基因的表达模式分析和关联分析，初步验证其功能，探索玉米穗粒腐病抗性的分子机制，为抗病ＱＴＬ利用奠定基础。

玉米穗粒腐病是世界上普遍发生、危害严重的一种真菌性病害，不仅直接影响了玉米的产量和品质，而且其病原菌产生的真菌毒素，给人、畜安全造成了严重威胁，选育抗病品种的成效取决于抗病遗传规律的了解。课题组选育和鉴定出1份优异抗源BT-1，并利用多亲本、多群体鉴定出１个主效QTL qRfv1，具有年份、地点、播期等多环境的稳定性。项目利用关联分析和连锁分析以及近等基因系平台进行抗病QTL验证的基础上，利用近等基因系的分析群体进行精细定位，结合混池测序、关联分析和转录组测序的结果，获得了主效QTL qRfv1的候选基因，为进一步研究抗病基因的功能以及抗病基因利用奠定了坚实的基础。创制的抗病基因的基因系和开发的抗病基因功能标记以及鉴定的优异等位基因可以服务于抗病育种实践。