Identification of QTLs Associated with indica-japonica Differentiation-Related Traits in Rice (Oryza sativa L.)

Understanding the morphological and physiological characteristics which are attributable to determine indica and japonica subspecies of Asian rice (Oryza sativa L.) is important to conceive breeding strategy. However, information of quantitative trait loci (QTLs) associated with targeted traits related to subspecies domestication and differentiation-related traits remains limited. Two reciprocal F2 mapping populations generated from a cross between Ilpumbyeo (japonica) and Dasanbyeo (indica) were developed and used for constructing genetic maps to identify QTLs responsible for subspecies specific-related traits using 107 sequence-tagged site (STS) markers. A total of 26 main-effect QTLs for subspecies-related traits such as grain length, grain width, grain length-width ratio, apiculus hair length, and potassium chlorate resistance, were detected on seven chromosomes (1, 2, 3, 4, 5, 6, and 8). Of the detected QTLs, 14 QTLs corresponding to the previously reported QTLs suggesting the functional conservation of QTLs across populations and the remaining 12 QTLs appeared to be novel QTLs. A total of 29 significant epistatic QTLs were also detected in present study demonstrating an important genetic basis of epistatic interactions for complex subspecies-related traits. These results suggest that the subspecies-related traits and detected QTLs should be taken into consideration to incorporate with marker-assisted selection strategy in rice breeding program.