Identification of QTLs for Cold Tolerance at Seedling Stage in Korean Weedy Rice (Oryza sativa L.)

Abstract

Molecular markers were used to map and characterize quantitative trait loci (QTLs) for traits related to cold tolerance in an intrasubspecific backcross population of rice. The parents of the cross were a cold susceptible Tongil-type cultivar “Milyang23” and a cold tolerant Korean japonica weedy accession “Hapcheonaengmi3”. A total of 98 BC1 plants derived from a Milyang23//Milyang23/Hapcheonaengmi3 cross were evaluated for seedling growth and the degree of cold injury with plumule at low temperature. A genetic linkage map was constructed for the same population using two morphological, two isozyme, 11 RFLP, 57 RAPD, 90 microsatellite markers that covered 1,733 cM of the rice genome with an average interval length of 10.7 cM. Interval analysis identified a minimum of seven significant QTLs for two traits with a range of 3~4 QTLs detected per trait. Direction of additive gene effect coincided with that predicted by phenotypes of the parents. The percentage of phenotypic variation associated with single QTLs ranged from 9.3 to 17%. Multilocus analysis showed that the cumulative action of all QTLs detected for each trait accounted for 31.8~38.1% of the phenotypic variation. Digenic epistasis was not detected. The identification of QTLs underlying the cold tolerance at the early growth stage may be useful in selecting lines with enhanced cold tolerance at low temperature.