Molecular Mapping of Sterility QTLs qSS-3, qSS-6a and qSS-7 as Single Mendelian Factors via NIL strategy

Hybrid sterility between Oryza glaberrima and O. sativa seriously hampers the introgression of favorable genes from each other. In order to further understand this issue, identification and isolation of hybrid sterility QTLs as single Mendelian factors are an effective strategy. A genetic map was constructed using a BC₁F₁ population derived from a cross between an O. sativa japonica cultivar and an O. glaberrima accession. Four main-effect QTLs for pollen sterility were detected in the BC₁F₁. Five BC₈F₁ advanced backcross populations were developed via successive backcrosses based on phenotype and molecular selections. The BC₈F₁ populations showed bimodal distribution for pollen fertility and could be classified into semi-sterile and fertile types, fitting single Mendilian factor inheritance ratios. Three QTLs detected in the BC₁F₁ corresponding to qSS-3, qSS-6a and qSS-7 were mapped on chromosomes 6, 3 and 7, respectively, as single Mendilian factors.