Pyramiding and interacting effects of QTLs for cold tolerance at the seedling stage in common wild rice，Oryza rufipogon Griff.

【Objective】There is a rich genetic diversity in common wild rice, Oryza rufipogon Griff.. Exploitation and effective analysis of cold tolerance quantitative trait loci (QTLs) from the wild rice could provide gene resources and theoretical support for rice cold tolerant molecular breeding. 【Method】In our previous study, a total of 18 cold tolerant QTLs distributing throughout all 12 chromosomes of rice genome were discovered using 230 chromosome segment substitution lines（CSSLs）which were developed from two crosses between the cultivar, 9311 as recipient parent and two lines of core resources of the common wild rice, DP15 and DP30 as donor parents. In this study, the interacting and pyramiding effects of four cold tolerant QTLs qSCT-1, qSCT-4, qSCT-8 and qSCT-12 which were previously identified in the CSSLs were studied using two pyramiding lines, (qSCT-1/qSCT-12)-CSSL and (qSCT-4/qSCT-8)-CSSL obtained from two crosses between qSCT-1-CSSL and qSCT-12-CSSL, and qSCT-4-CSSL and qSCT-8-CSSL respectively against a uniform genetic background. 【Result and conclusion】The results indicated that four cold-tolerance QTLs with an additive effect could significantly improve the resistance to rice cold stress separately; there might exist positive interaction effect among these cold tolerance QTLs in pyramiding lines. There was a significant addition effect between qSCT-4 and qSCT-8, but no significant epistasis effect between qSCT-12 and qSCT-1.