[The platform of breeding by design based on the SSSL library in rice].

Breeding by design is a new concept proposed in the beginning of the century. It refers to the breeding of varieties by crop design utilizing favorable alleles dispersed in different genetic resources in a genome. In the past 20 years, we have proposed a "three-step" strategy to carry out the research on breeding by design in rice. Firstly, we constructed a library of chromosomal single-segment substitution lines (SSSLs) by using of Huajingxian74 (HJX74), an elite xian (indica) variety from South China as the recipient and 43 accessions of seven species of rice AA genome as donors. The genes in the substituted segments of SSSLs were then detected. Breeding by design was conducted by selecting the favorable genes from the SSSL library. Our practice indicates that the SSSL library is a powerful platform for breeding by design and various "traits", "lines" and "varieties" of rice can be designed and bred by utilizing abundant genes in the SSSL library. Here, we introduce the platform of the HJX74-SSSL library and our work of breeding by design on the platform. It will provide a case study for crop design.