Genomic Regions Affecting Heading Date and Culm Length in a Backcross Line from a Cross between Oryza sativa and O. grandiglumis

Abstract

Through earlier breeding efforts, portions of the genome of the wild species Oryza grandiglumis (2n=48) have been introgressed into the rice cultivar, Hwaseongbyeo (Oryza sativa spp. japonica). Hwaseongbyeo was used as recurrent parent and O. grandiglumis was used as donor parent. An advanced backcross line, HG101 from a single plant of BC5F3 families displayed differences compared to Hwaseongbyeo in a number of traits including days to heading (HD) and culm length (CL). These differences between HG101 and Hwaseongbyeo could be attributed to the O. grandiglumis chromosome segments introgressed into HG101. To identify and characterize the effects of alien gene(s) introgressed into HG101, F2:3 lines from the cross between Hwaseongbyeo and HG101 were developed and evaluated for days to heading and culm length. Genotypes were determined for 150 F2 plants using polymorphic SSR markers. QTL analysis was carried out to determine the relationship between marker genotype and two traits, HD and CL. One QTL underlying HD was detected on chromosome 11. Three QTLs on chromosomes 1, 8 and 11 were associated with CL, respectively. The phenotypic variation explained by each QTL ranged from 16.7 to 23.2%. QTLs controlling HD and CL identified in this study have not been detected in previous QTL studies involving Oryza cultivars indicating introgression of potentially novel alleles from O. grandiglumis. The QTLs detected in this study might provide a source of information about the natural genetic variation underlying the evolution and breeding of rice.