Identification of Dwarfing Candidate Genes in Brassica napus L. LSW2018 through BSA-Seq and Genetic Mapping

Plant height, as a crucial component of plant architecture, exerts a significant influence on rapeseed (Brassica napus L.) lodging resistance, photosynthetic efficiency, yield, and mechanized harvest level. A previous study identified dwarf rapeseed LSW2018. In this study, LSW2018 (dwarf parent (PD)) was crossed with 389 (high parent (PH)) to establish the F-2 population, and 30 extremely dwarf (bulk-D) and high (bulk-H) plants in the F-2 population were respectively selected to construct two bulked DNA pools. Whole-genome sequencing and variation analysis (BSA-seq) were performed on these four DNA pools (PD, PH, bulk-D, and bulk-H). The BSA-seq results revealed that the genomic region responsible for the dwarf trait spanned from 19.30 to 22.19 Mb on chromosome A03, with a length of 2.89 Mb. After fine mapping with simple sequence repeat (SSR) markers, the gene was narrowed to a 0.71 Mb interval. Within this region, a total of 113 genes were identified, 42 of which contained large-effect variants. According to reference genome annotation and qRT-PCR analysis, there are 17 differentially expressed genes in this region between high and dwarf individuals. This study preliminarily reveals the genetic basis of LSW2018 dwarfing and provides a theoretical foundation for the molecular marker-assisted breeding of dwarf rapeseed.