QTL Analysis of Field Resistance to Brown Leaf Spot in F1 Population of Non-inbred Parents in Cassava
利用非近交亲本间杂交F1群体对木薯褐斑病田间抗性的QTL分析

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% of phenotypic variance. Six of them on groups 1 and 2 were important QTLs.