Abstract:

Single segment substitution line (SSSL) is a power tool for mapping, cloning and functional analysis of genes. In this study, A SSSL population was developed using a Indica cultivar “Huajingxian 74” as recipient and 12 accessions including 8 Indica and 4 Japonica as donors (Table 1 and Fig.1). Five hundreds and forty-nine SSR markers with an average marker interval about 2.8 cM on the rice microsatellite map were used to survey the polymorphism between parents. The polymorphisms between the 12 donors and the recipient were varied from 33.0% to 70.7% with an average of 50.0% (Table 2). By backcrossing four or five times, a series of candidate SSSLs were selected. The genetic backgroud in the candidate SSSLs was examined in BC₄F₁, BC₄F₂, BC₅F₁ or BC₅F₂. The samples with residual segments from the candidate SSSLs were 1.07% (Table 3). Discarding the candidate SSSLs with residual segments, a total of 260 SSSLs were developed, of which 74 SSSLs were selected from BC₄F₂, 134 SSSLs from BC₄F₃ and other 52 from BC₅F₂ (Table 4). Each SSSL contained a single defined homozygous chromosome substituted segment from one of the twelve donors in the Huajingxian 74 genetic background. The estimated lengths of the substituted segments ranged from 0.2 cM to 109.9 cM with an average of 19.9 cM (Fig.2 and Table 4). Total length of the substituted segments in the SSSL population was 5166.0 cM, which was about 3.4 times of the rice genome. The substituted segments in the SSSLs were distributed on 12 chromosomes (Fig.3 and Table 5) and provided a coverage of 83.8% of the rice genome (Table 4). These SSSLs will play an important role in the study of functional genomics and molecular breeding in rice.

Key words: Oryza sativa L., Single segment substitution line, Marker-assisted selection