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

Abstract

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 F2 population, and 30 extremely dwarf (bulk–D) and high (bulk–H) plants in the F2 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.