Seed storability in rice (Oryza sativa L.) is an important agronomic trait. Two segregating populations with N22 (indica) as a common parent, viz. a set of 122 backcross-inbred lines (BILs) derived from the backcross Nanjing35 (japonica)/N22//Nanjing35 and another population comprising 189 recombinant inbred lines (RILs) from the cross of USSR5 (japonica) and N22, were studied to detect quantitative trait loci (QTL) controlling seed storability. Germination percentage (GP) was used to evaluate seed storability after aging treated under three different conditions, viz. natural, artificial and combined aging treatments. A total of seven QTLs were identified on chromosomes 1, 2, 5, 6 and 9. Among them, a major QTL, qSSn-9, was common in the two populations. In contrast, four QTLs (qSSnj-2-1, qSSn-2-2, qSSn-5 and qSSn-6) were detected in BILs and the QTL qSSn-1 was identified in RILs, which was a new QTL for seed storability. The N22-derived alleles increased the seed storability at all the loci except qSSnj-2-1. We also investigated the effect of QTLs using five selected lines with high storability from BILs and verified qSSn-5 with a near-isogenic line (NIL). These results provide an opportunity for pyramiding or map-based cloning major QTLs for seed storability in rice.

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, SL36, 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 F2 population from a cross between ‘Nipponbare’ and SL36 was used for fine mapping of qSS‐9. Simultaneously, four subnear isogenic lines (sub‐NILs) that represented different recombination breakpoints across the qSS‐9 region were developed from F3 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.