利用非近交亲本间杂交F_1群体对木薯褐斑病田间抗性的QTL分析

QTL Analysis of Field Resistance to Brown Leaf Spot in F_1 Population of Non-inbred Parents in Cassava

对非近交亲本抗褐斑病的文昌红心和中感亲本华南6号杂交获得分离群体184个株系,采用简单重复序列(Simple Sequence Repeat,SSR)分析,检测了木薯(Manihot esculenta Crantz)对褐斑病田间抗性的数量性状基因位点(Quantitative Trait Locus,QTL)。采用田间自然发病和辅助人工接菌的方法,分别在2004年苗期、2005年苗期和成株期3次调查和鉴定了群体的抗病性反应。结果表明,这3个时期群体褐斑病病情指数(DI)分布范围较一致,均呈连续性偏峰态分布。从400对SSR引物中筛选出在抗、感基因池和两个亲本间均具有多态性的引物17对,群体检测获得50个等位基因位点,构建了包含34个位点的8个连锁群,覆盖木薯基因组695.7cM,2个位点间平均图距为20.5cM。采用复合区间作图法进行QTL分析,共检测到15个与木薯褐斑病抗性相关的QTL,贡献率在9.61%-64.81%,主要分布在第1、2、4连锁群的特定区域。其中,第1、2连锁群上的6个QTL是重要的QTL。

One hundred and eighty-four lines of F1 hybrid between non-inbred parent Wenchang red resistant to brown leaf spot and moderately susceptive South China 6 were used to detect quantitative trait loci （QTLs） for field resistance to brown leaf spot （Cercosporidium henningsii） of cassava （Manihot esculenta Crantz） by simple sequence repeat （SSR） markers. Disease response was investigated under field conditions assisted with artificial inoculation during 2004-2005 seedling stages and 2005 grown-up stage of cassava. Disease index showed a skewed distribution, indicating that major effective genes exited. Seventeen out of 400 SSR primers were screened based on DNA amplification of resistance and susceptive gene pools and two parents. Fifty alleles were found using the 17 SSR primers. Eight linkage groups associated with 30 alleles were constructed covering a length of 695.7 cM with an average marker distance of 20.5 cM. A total of fifteen QTLs for resistance were identified, located on groups 1, 2, 3 and 4, accounting for 9.61%-64.81% ofphenotypic variance. Six of them on groups 1 and 2 were important QTLs.