QTL Mapping for Cold Tolerance at the Seedling Stage in Rice

Rice (Oryza sativa L.) is a nationally and internationally important staple food.It is a cold sensitive crop.Abiotic stress factors are the major constraints not only in rice but also in present agriculture.Cold stress reduces crop yield, their quality and postharvest life.Rice is injured or killed by non-freezing low temperature, and exhibit various symptoms of chilling injury such as chlorosis, necrosis, or growth retardation.In contrast, chilling tolerant species are able to grow at such cold temperatures.Sometimes the plant badly suffers from cold stress during seedling stage when they are grown in winter environment.Consequently, mining cold-tolerant germplasm and mapping cognate genes would provide an opportunity to ameliorate rice yield through marker-assisted selection (MAS).Many quantitative trait loci (QTL) for cold tolerance at seedling stage in rice have been identified and mapped.This information is necessary for understanding of the complex network of molecular changes that are important for chilling and freezing tolerance in crop plants.The development of cold tolerant plants by the introduction of molecular breeding seems to be a viable option to hasten the breeding of 'improved' plants.Intuitively, molecular breeding would be a faster way to mapping of beneficial QTL than through conventional breeding.Although much progress has been accomplished, joint achievement from breeders and plant biotechnologist could expedite the engenderment of cold-tolerant rice plants, and some possible approaches are suggested.