Mapping quantitative trait loci associated with regeneration ability of seed callus in rice, Oryza sativa L.

Quantitative trait loci (QTL) controlling the regeneration ability of rice seed callus were detected using 245 RFLP markers and 98 BC1F5 lines derived from two varieties, 'Nipponbare' and 'Kasalath'. Regeneration ability was evaluated by two indices: average number of regenerated shoots per callus (NRS) and regeneration rate (RR). The BC1F5 lines showed continuous segregation for both indices. Five putative QTL for NRS (tentatively named qRgl, qRg2, gRg4a, qRg4b and qRg4c) located on chromosomes 1, 2 and 4 were detected. Digenic interaction among these detected QTL was not significant (P < 0.01). Among the five QTL detected, four 'Kasalath' alleles and one 'Nipponbare' allele increased NRS. According to an estimate based on the nearest marker loci, the five QTL accounted for 38.5% of the total phenotypic variation of the BC1F5 lines. For RR, four putative QTL were detected on chromosomes 2 and 4, and all of these were in the same chromosomal regions as the NRS QTL. The four RR QTL accounted for 32.6% of the total phenotypic variation.