Fine Mapping Of TSWA7a For Seed Weight And Identification Of It’s Candidate Gene In Brassica Napus

Thousand seeds weight is one of the main agronomic traits screened in the evolution process of Brassica napus.And it’s one of the most important yield components.Based on the localization of TSW locus TSWA7 a and the target region BAC we screened,we conducted fine mapping and map-base cloning for this QTL.And the functions of the two candidate genes were further studied.This work provides new information and new resources for the analysis of the regulatory mechanism of seed size and yield of rapeseed.The results obtained are as follows:1.Base on the previous mapping result,we screened BAC with 8 evenly distributed markers in the candidate regions between SSR434 and BA07-120,38 BAC clones of two alleles were obtained.While fourteen BAC clones were selected and sequenced.With the 51 In Dels developed by sequencing of BAC,we chose 3 codominance In Dels for fine-mapping.2.Thousand seeds weight of BC7F2:3 and BC8F2 population was investigated.It was found that the thousand seeds weight of both populations were continuously distributed.By using BC7F2:3 phenotype and genotype data,QTL scanning was performed.The TSWA7 a locus was locked between BA07-145 and BA07-81 with an LOD value of 7.10.The additive and dominance effects were-0.30 g and-0.04 g,respectively.3.We found 21 ORFs in the target region through analysis of NIL re-sequencing data.Via analyzing Arabidopsis mutant of their homologous gene,significant differencewere found in TSW for the two genes(gene11 and gene15).And throughtranscriptome analysis of different stages,their differential expression time arecoincide with the seeds weight differentiation stage of the two genotype NILs.Homologous genes of these two candidate genes were annotated as WD40 repeatsuperfamily protein coding gene.4.The CRISPR vectors of gene11 and gene15 were constructed and were introduced into rapeseed.We obtained 25 and 18 mutant plants respectively.And the mutation sites were sequenced to confirm their edit type.