栽培大豆中抗大豆胞囊线虫病新主效抗性QTL的精细定位

Soybean cyst nematode (SCN, Heteroderaglycines Ichinohe) is the most destructive pest of soybean worldwide. Host plant resistance is an effective approach to control this pest. However, most SCN-resistant varieties have been derived from PI 88788 and 548402 (Peking). The most important loci underlying SCN resistance in PI 88788 and Peking are Rhg1 and Rhg4. It has been shown that the continuous cultivation of the same source of resistance has resulted in genetic shifts of SCN populations, which could eventually overcome the plant resistance genes. Lack of diversity for SCN resistance genes in soybean cultivars requires further investigation to identify new SCN genes. JSCN-25 showed broad and specific spectrum resistance to multiple-race of SCN and JSCN-25 without Rhg1 and Rhg4 loci. The molecular basis underlying broad-based SCN resistance in JSCN-25 is unknown. The objective of this study is to fine map novel quantitative trait loci (QTL) for SCN resistance to race 3. Mapping will be conducted using F2 progeny derived from a William 82 (susceptible) × JSCN-25 (resistant) cross and a Hutcheson (susceptible) × JSCN-25 (resistant) by using QTL-Seq and chromosome walking methods. And the candidate genes about the major QTLs will be predicted. Our studies will provide useful information for deploying JSCN-25 as a donor for SCN resistance in soybean breeding through marker-assisted selection.

大豆胞囊线虫病是一种大豆生产的毁灭性病害，防治这一病害的最佳途径是选育和种植抗病品种。目前大豆品种的抗性基因主要源自PI 88788 和Peking，主效基因是Rhg1和Rhg4，然而长期种植单一的抗性品种会使其抗性丧失，因此亟需发掘新的抗性品种和基因资源。在前期工作中发现大豆种质JSCN-25兼抗多个大豆胞囊线虫生理小种，抗虫谱明显区别于PI 88788 和Peking，经全基因组测序确定其不含有Rhg1与Rhg4 抗性基因，由此预测该种质含有新的重要抗性基因。本项目将利用抗性亲本JSCN-25 与易感亲本William 82和Hutcheson组成的两个杂交组合的F2群体，用QTL-Seq和染色体步移的方法精细定位该品种中对大豆胞囊线虫3号生理小种具有抗性的主效QTLs并预测候选基因，揭示JSCN-25抗性的遗传基础，为大豆抗胞囊线虫基因功能研究和分子标记辅助育种提供科学依据。

大豆胞囊线虫病是一种大豆生产的毁灭性病害，防治这一病害的最佳途径是选育和种植抗病品种。目前大豆品种的抗性基因来源单一，亟需发掘新的抗性品种和基因资源。因此，本项目利用前期鉴定的新抗性种质JSCN-25，与易感亲本Magellan 进行杂交，构建了包含200个单株的F2 作图群体，发掘新的针对胞囊线虫3号小种的抗性QTL位点，并结合转录组学分析手段，预测了候选基因。本项目研究内容包括（1）使用SLAF-seq 的方法获得高密度遗传连锁图谱，结合F2:3家系对胞囊线虫3号小种的抗性鉴定结果，定位了两个主效胞囊线虫抗性QTL位点，其中一个为新抗性位点qSCN-10（Gm 10: 42660451..42881952），另一个QTL位点与 Rhg1 位点重合。（2）利用RNA-Seq技术分析抗感亲本接种胞囊线虫前后的转录组变化情况，结合QTL定位结果预测了7个候选基因。（3）基于抗感亲本接种胞囊线虫前后的转录组变化情况，初步分析JSCN-25的抗性机制，认为植物先天免疫在抗性过程中起重要作用。候选基因的功能验证工作正在进行中。.