QTL mapping for cold tolerance with specific reference to rice

Abstract

Rice is a staple food for more than half the world’s population. It has highest global production next to wheat. With global climate change, most rice growing regions are experiencing extreme environmental fluctuations. Rice is susceptible to a variety of abiotic stresses including cold stress. In the temperate regions, rice growth is constrained by limited period that favours growth, where it needs optimum temperature between 25 0C to 35 0C. As the temperatures goes below 15oC, rice crop shows a wide range of chilling injury depending on the length of exposure and the developmental stage. Seedlings subjected to prolonged exposure (i.e. several days to weeks) can exhibit necrosis and mortality while shorter or intermittent exposure often leads to yellowing (chlorosis) and stunting, thus greatly reducing rice yields. Many QTLs related to cold tolerance at different stages have been identified by different researchers using mapping populations like recombinant inbred lines (RILs), doubled haploids (DH), F2:F3 lines, backcrosses and introgression lines. Therefore, the development of cold tolerant plants by the introduction of molecular breeding is assuredly a meaningful approach to hasten the breeding for improved plants. Intuitively, molecular breeding would be a faster way to mapping of beneficial QTL than through conventional breeding. The QTLs identified could be brought together by pyramiding into the breeders’ material and thus reduce the negative effect of cold stress.