大豆对斜纹夜蛾和筛豆龟蝽抗性遗传体系的比较与兼抗育种

Common cutworm [Spodoptera litura (Fabricius)] and globular stink bug [Megacota cribraria (Fabricius)] is polyphagia chewing pest and oligophagous sucking pest, respectively. The two pests are the most common leaf-feeding pests infecting soybean in Southern China. They may overlap and soybean plants may be infected with both insects. Therefore control these two insects is an essential to improve the soybean production. This challenge is more difficult by the fact that understanding the genetic mechanisms of resistance, thus relatively limited breeding effort and selection is conducted. Previously we performed high throughput phenotype screening and found resistant germplasm to S. litura is susceptible to M. cribraria and vice versa. We developed a recombinant inbred line (RIL) population NJRILY containing 326 F8:9 families, with high resistant to S. litura but highly susceptible to M. cribraria soybean cultivar Lamar as female parent, high resistant to M. cribraria but susceptible to S. litura soybean cultivar Nannong 1138-2 as male parent. At the same time, a high density molecular linkage map has been also constructed. Further we aimed to find major QTL, candidate genes responsible for resistance to S.litura and M. cribraria and understand the genetic relationship between the mechanisms of resistance to respective insects. For that first we have planned to map the QTL of antixenosis, antibiosis and physical & chemical traits (the content of flavonoids and leaf pubescence traits) related to resistance and then we will compare the QTL mapping results to find the major QTL for resistance to the two insects. Further verify the QTL and delimit the candidate genomic region, we will use secondary mapping population. The secondary mapping population will be developed by hybridization between family or residual variation and then candidate genes will be selected by association/functional studies. Furthermore we have planned to pyramid the QTL resistance and breed new soybean germplasm resistance to both S. litura and M. cribraria by marker assisted selection.

斜纹夜蛾和筛豆龟蝽分别是严重危害我国南方大豆的杂食性咀嚼式和寡食性刺吸式害虫。两种害虫在我国南方混合发生，抗性遗传机制尚不明确，严重阻碍了抗虫育种工作。申请者发现大豆对斜纹夜蛾和对筛豆龟蝽的抗性种质不同，以高抗斜纹夜蛾但高感筛豆龟蝽的大豆品种Lamar为母本，高抗筛豆龟蝽但感斜纹夜蛾的大豆品种南农1138-2为父本，构建了包含326个F8:9家系的重组自交系群体NJRILY且构建了高密度分子遗传图谱。计划评价该群体对两类害虫的抗选性、抗生性，同时检测抗性相关性状黄酮类物质含量和叶片茸毛性状。通过QTL定位，比较大豆对不同虫种的不同抗性机制及抗性相关性状间遗传体系的异同，发掘出主效QTL。通过构建剩余杂合系等次级群体，对主效QTL进行精细定位，获得候选基因，并通过关联分析进行验证。利用所得抗虫QTL/基因信息，通过家系间杂交结合分子标记辅助选择选育兼抗新种质。

建立了温室内套建小型网室作为鉴定场所，用32穴育苗盘作为大豆种植载体，用三龄斜纹夜蛾幼虫侵染V1阶段的大豆幼苗，以叶面积损失率为指标，动态地对整个危害过程进行评价的抗选性鉴定方法。该方法缩小了试验空间和周期，具有简单易行、成本低廉、可操作性强等特点。建立了基于咀嚼式口器食叶性害虫取食叶片的凸包图计算虫孔个数和虫孔面积的叶片损失率测量方法。提出了在虫害关键时期（R3）以33.3%的剪叶量模拟咀嚼式食叶性害虫危害，以单株荚数、百粒重及单株产量等损失率作为评价指标鉴定大豆的耐虫性。在CO2浓度升高的情况下生长的抗虫和感虫大豆品种叶片氮含量显著降低，叶片碳含量和C/N比显著升高，同时对斜纹夜蛾的生长产生负面影响。与感虫大豆相比，抗虫大豆的叶片碳含量和C/N比增加更大。因而叶片碳含量和C/N在大豆的抗虫性中起重要作用。通过三个批次的苗期试验和室内喂养初孵幼虫评价了重组自交系群体NJRILY对斜纹夜蛾的抗选性和抗生性。抗选性与抗生性都在7号染色体上检测出一个抗虫主效QTL，发现候选基因Glyma07g13780和Glyma07g14340在叶片中表达量较高。控制叶片正面茸毛长度的QTL位于1、7和12号染色体，其中12染色体上的QTL效应最大。控制叶片正面茸毛密度的QTL位于1、3和12号染色体，其中1号染色体上的QTL最稳定。1和12号染色体上的茸毛密度与长度QTL，位置非常相近，同时影响茸毛密度与长度，但效应相反。7号染色体的QTL只影响茸毛长度，与抗斜纹夜蛾的主效QTL位置相近，说明茸毛长度可能与大豆对斜纹夜蛾的抗虫性有一定的关系。茸毛有无剩余杂合系喂养斜纹夜蛾幼虫试验说明茸毛的存在增加了大豆对斜纹夜蛾的抗生性。连锁分析和关联分析都在1和12染色体发掘出大豆抗筛豆龟蝽主效QTL，与大豆对斜纹夜蛾的主效抗性QTL位于不同染色体，说明大豆对两种害虫的抗性机制不同。对筛豆龟蝽的抗性与茸毛着生状态相关，对斜纹夜蛾的抗性可能与茸毛长度有关。分析了抗斜纹夜蛾的分子标记辅助选择效率。选育出兼抗斜纹夜蛾和筛豆龟蝽的优良种质。