Genetic dissection of salt tolerance architecture in Brassica napus at the seedling stage by genome-wide association study

Abstract

Owing to the continuous increase in industrialization, the extent of soil salinization is escalating globally. Brassica napus is among the most advantageous field crops for the development and utilization of saline - alkali land. Nevertheless, the molecular regulation of salt tolerance during the seedling stage in this species remains unclear. To explore this mechanism, an association population consisting of 202 accessions was subjected to a 257 mmol/L NaCl solution at the seedling (four - leaf) stage. After 14 days of salt treatment, the above - ground and under - ground fresh and dry weights of each accession line were measured, and the correlations between these traits were evaluated. By integrating phenotypic data with resequencing data, a genome - wide association study identified 2043 single nucleotide polymorphisms (SNPs) that were significantly associated with these traits. Ninety SNPs were detected repeatedly, with a single SNP accounting for 1.3%–5.29% of the phenotypic variation. Subsequently, two candidate genes were identified, and six germplasm resources with strong salt tolerance at the seedling stage were selected. These results will guide strategies for breeding salt - tolerant B. napus and will offer a theoretical foundation for the restoration and management of salinized land.