The Research Of Fine Mapping Of Hybrid Lethality Gene BoHL2 In Cabbage(Brassica Oleracea L.var.capitata)

Hybrid lethality, a type of postzygotic reproductive barrier, is the phenomenon that the two parents grow normally but theirs F1 hybrids die before sexually mature. Location of the hybrid lethal gene is the molecular basis of cloning hybrid lethality genes, meanwhile laying the foundation for clarifying the mechanism of hybrid lethality.In this study, we observed the hybrid lethality phenomena in a cross between two cabbage inbred lines, 09-211 and 09-222. Genetic analysis revealed that the hybrid lethality was controlled by two complementary dominant genes, BoHL1 and BoHL2, from 09-211 and 09-222, respectively. The genetic mechanism conformed to the 2 loci Bateson-Dobzhansky-Muller model. On the basis of this study, we used 09-222 first crossed with 87-534, 11-196 and 96-100 to obtain the F1, then crossed with 09-211 to construct the segregation populations for BoHL2 fine mapping, which lay the foundation for cloning and functional analysis of hybrid lethality genes. The results are as follows:1. Preliminary mapping of cabbage hybrid lethal gene BoHL2To map the lethal BoHL2 gene from 09-211, BSA was conducted on 336 individuals derived from the segregation population(09-222 × 87-534) × 09-211 to identify six polymorphic markers on chromosome C04 linked to the BoHL2, six pairs of primers including InDel0110, InDel0112, InDel0114, D349, LTSSR342, and LTSSR346. Linkage analysis revealed that BoHL2 was located between LTSSR346 and InDel0114. The interval distance between the two markers was 6.65 Mb. According to the flanking marker LTSSR346 and InDel0114, 73 pairs of primers were developed by comparing the 10 ? coverage re-sequencing data from 09-211 and 09-222 and obtained 33 polymorphic markers with good and stable amplifications. Enlarging segregation population(09-222 × 87-534) × 09-211, we mapped BoHL2 on the C04 chromosome by HL211 and HL249. The interval distance was 1.8 Mb.2. Fine mapping of cabbage hybrid lethal gene BoHL2Two additional large mapping populations(09-222 × 11-196) × 09-211 and(09-222 × 96-100) × 09-211 was chosen. Fine mapping BoHL2 on the C04 chromosome by HL235 and HL234 at a distance of 0.3 cM and 0.3 cM, respectively. The physical distance was 70.33 Kb.3. Candidate gene analysisThe mapping region contained 9 genes according to the annotations of B.oleracea. In which, Bol033387 and Bol033390 have the domain of resistant genes. Besides, the analysis of the Indel and SNP sites from the five hybrid lethal cabbage inbred lines’ mapping region indicated that most of sites loacated on the region of Bol033385. So, we identified the three genes are canadidate genes.