Fine mapping of qSS‐9, a major and stable quantitative trait locus, for seed storability in rice (Oryza sativa L.)

Seed storability in rice ( Oryza sativa L.) is an important agronomic trait. We previously showed a quantitative trait locus of seed storability, qSS ‐9 , on chromosome 9 in a backcross population of ‘Koshihikari’ ( japonica ) / ‘Kasalath’ ( indica ) // ‘Koshihikari’. In this study, fine mapping of the chromosomal location of qSS ‐9 was performed. Effect of ‘Kasalath’ allele of qSS ‐9 was validated using a chromosome segment substitution line, SL 36, which harboured the target quantitative trait loci ( QTL ) from ‘Kasalath’ in the genetic background of ‘Nipponbare’ under different ageing treatments in different environments. Subsequently, an F 2 population from a cross between ‘Nipponbare’ and SL 36 was used for fine mapping of qSS ‐9 . Simultaneously, four subnear isogenic lines (sub‐ NIL s) that represented different recombination breakpoints across the qSS ‐9 region were developed from F 3 progeny. Finally, the qSS ‐9 locus was located between the Indel markers Y10 and Y13, which delimit a region of 147 kb in the ‘Nipponbare’ genome. These results provide a springboard for map‐based cloning of qSS ‐9 and possibilities for breeding rice varieties with strong seed storability.