Studies On The QTLs For Tolerance To Chilling Injury And Marker-assisted Selection For Cold Tolerance Gene In Rice

Chilling injury of rice seedling under natrual field conditions is one of the most important limiting factors in many rice cropping regions in China. In this study, a RIL population of 86 plants developed from a cross between a seedling cold tolerance variety 743 and a cold susceptible variety Dular was evaluated for seedling cold relative character. A linkage map was constructed by using 90 microsatellite markers. Under low temperature treatment, five putative QTLs on chromosome3, 5, 6 (two QTLs) and 9 for chlorophyll contents, four QTLs on chromosome 2, 3, 9 and 12 for malondialdehyde contents and five QTLs on chromosome 1 (two QTLs) ,3, 9 and 11 for chilling injury were mapped. The phenotypic variation explained by individual QTLs varied from 3.07% to 17.15%. In this population, we found loci RM105～RM257 on chromosome 9 and OSR16～RM7 on chromosome 3 affected chlororhyll contents, malondialdehyde contents, wither and dying. Therefore they were major QTLs controlling seedling cold tolerance.To solve the problem of poor tolerance to coolness at the booting stage in rice in the south of china, we transferred cold tolerance gene from a cultivar-Hokkai PL₅, which is tolerant to cold at the booting stage, into three elite indica varieties: Xiangwan 29, Xiangwan 31 and Taizhong 101, respectively. Two CAPs markers closely linked to the cold tolerance gene were conducted in the F₃ population and we picked out four, two and six individuals respectively, with homozygous gene of resistance to chilling injury at the booting stage, so that they could be used as important breeding materials. Meanwhile, a simple, rapid and accurate analysis system of CAPs marker-assisted selection was established.