QTL analysis of the rice seedling cold tolerance in a double haploid population derived from anther culture of a hybrid between indica and japonica rice

A doubled haploid population, derived from anther culture of F-1 hybrid bet ween a typical indica cv. and a japonica cv. has been used to investigate t he seedling cold tolerance (SCT) in growth cabinet, By dynamically analyzin g every day's survival percentages of the parents and DH lines under 7-d co ld plus 9-d normal temperature condition, the quantitative trait loci (QTLs ) for SCT have been mapped based on a molecular linkage map constructed fro m this population. The results show that two parents had significant differ ences in SCT and the segregation of SCT in DH lines was basically a continu ous distribution with most serious injury on the 6th d of the cold treatmen t. A total of 4 QTLs for SCT have been identified on chromosomes 1, 2, 3 an d 4 respectively. The additive effects of qSCT-1, qSCT-2 and qSCT-3 have be en contributed by the japonica cv JX17, but that of qSCT-4 has been contrib uted by the indica cv ZYQ8. The mechanism of SCT seems complicated since th e above 4 QTLs detected at different stages during the treatment. Further s tudy on the genotypes for these SCT QTLs in the DH lines shows transgressiv e segregation. It is demonstrated that the lines with stronger SCT over JX1 7 have 3-4 loci for SCT. Integration of these QTLs into an appropriate vari ety may lead to a successful rice breeding program for cold tolerance.