Construction Of Indica/japonica Hybrid Double Haploid Population And Mapping Of SDL In Rice(oryza Sativa L.)

Rice anther culture technology can not only create useful genetic variation,but also quickly obtain homozygous plants with good characters and accelerate the breeding process,which has become an important technical means in modern rice breeding.It may take 6-8 generations for traditional breeding methods with repeated self-crossing that breed stable and good character lines,but the Double Haploid（DH）population constructed by rice anther culture technique can greatly shorten the breeding cycle.Previous studies have shown that the anther culture ability of rice was highly dependent on genotype and showed the characteristic of quantitative character inheritance.The general trend of callus induction ability of different rice varieties and their hybrids was waxy rice>japonica>japonica hybrid rice>japonica/indica hybrid rice>indica hybrid rice>indica rice,and there were great differences among different varieties of the same type of rice.However,the underlying molecular mechanism of anther culture ability remains unclear.The reason of SD in DH population is due to microspores within anthers bearing desirable alleles,which in favor of anther culture ability,would be selectively transmitted to DH lines during the anther culture processes.Thus,characterized the underlying locus and genes of SD is crucial for elucidating the genetic mechanism that controlling the anther culture ability.Indica variety Fan 38 and japonica variety Shenhui 26 were crossed to obtain F₁generation.The anther culture of F₁ and BC₁F₁ generation was carried out and constructed a DH population containing 154 lines and 1912 lines,the highest anther culture efficiency is 28.91%.The 2b-RAD genotyping approach was used to construct a high density SNP molecular marker genetic map to identify Segregation distortion locus（SDL）.Five SDLs were detected on chromosomes 2,3,7,9 and 11,with LOD values ranging from 3.74（SDL7）to 41.49（SDL9）.The analysis identified a total of 9 epistatic locus-pairs.Meanwhile,the two-locus interaction region between chromosome 2 and 3overlaps with SDL2 and SDL3 which display SD at the single-locus level.It was found that the SD in SDL2 and SDL3 regions was significantly inclined to the Shenhui 26 allele of japonica rice parent.Meanwhile,SDL7,SDL9 and SDL11 were significantly inclined to the Fan38 allele in indica rice,and the complete disappearance of the male parent Shenhui 26 allele in the SDL9 region suggests the presence of a pollen lethal gene near this region.Further analysis of the recombination of DH populations from BC₁F₁generation narrowed the pollen lethal gene that near SDL9 to a region of about 295kb.These results are of great significance to reveal the genetic regulation mechanism of anther culture,improve the efficiency of anther culture,increase rice yield and accelerate the process of rice breeding.