Fine Mapping And Analysis Of Candidate Genes BoHL1 And BoHL2 Associated With Hybrid Lethality In Cabbage(Brassica Oleracea L. Var. Capitata)

Plant hybrid lethality is defined as the phenomenon that parents can grow normally,while F₁generation exhibits wilting,chlorosis,growth dwarfed,and lethality.Hybrid lethality,a postzygotic reproductive isolation phenomenon,plays an important role in the evolution of species.Based on previous studies,we continues to build more separation groups for fine mapping of BoHL1 and BoHL2.We also performed candidate gene analysis in the mapping region,which lay the foundation for cloning and functional analysis of hybrid lethality genes.The results are as follows:1.Fine mapping of cabbage hybrid lethal gene BoHL1 and BoHL2Fine mapping of cabbage hybrid lethal gene BoHL1:five additional large mapping populations（09-211×87-534）×09-222 was built to mapping BoHL1.BoHL1 was mapped between X594 and X538by InDels and SSRs,the physical distance was 70.33 Kb.Then BoHL1 was fine-mapped between K102and K107 by KASP,flanking it with genetic distances of 0.04cM and 0.01cM respectively,The physical distance was 56Kb（C1:42801015-42857181）.Fine mapping of cabbage hybrid lethal gene BoHL2:based on the predecessors’mapping result,we get three polymorphic primers by designing new InDels between HL234 and HL235.BoHL2 was fine-mapped between L613 and L618,flanking it with genetic distances of 0.1cM and 0.1cM,the physical distance was 27Kb（C4:46366966-46393632）.2.Candidate gene analysis of hybrid lethality genesAccording to TO1000 reference genome,the mapping region of BoHL1 contained 17 genes,the mapping region of BoHL2 contained 5 genes,respectively.We used analysis of gene function,re-sequencing and RNA-Seq,combination of qRT-PCR and gene amplification to analysis these genes.We proposed that Bo1g153250,Bo1g153270,Bo1g153280,Bo1g153320,Bo1g153330,Bo1g153380,Bo1g153400 may be associated with hybrid lethality in cabbage in the fine mapping region of BoHL1;Bo4g173750,Bo4g173780,Bo4g173790 may be associated with hybrid lethality in cabbage in the fine mapping region of BoHL2.Annotations of Bo1g153320,Bo1g153380,Bo4g173780 are related to reported hybrid lethality genes,and nucleotide variations between two parents and relative expression difference between seedling stage and hybrid lethality stage were detected,so we focus on Bo1g153320,Bo1g153380,Bo4g173780.3.Screening and identification of hybrid lethal materialsIn 2016-2017,the combinations which were obtained by the inbred lines 09-211,09-222 and other inbred lines were used as test materials,11 inbred lines were identified as hybrid lethal materials which carry BoHL2.