Comprehensive evaluation of compound saline-alkali tolerance and gene mining by GWAS in Vicia faba L.

Background: Faba bean ( Vicia faba L.) is a crucial cool-season legume crop, which is highly valued for its high protein content and key role in crop rotation systems. Considering the increasing threat of soil salinity and alkalinity globally, it is critical to screen germplasm resources with salt and alkali tolerance in faba bean and to identify the underlying genes. Results: In this study, 12 morphological and physiological traits under compound saline-alkali stress were measured to evaluate saline-alkali tolerance of 240 germplasm based on principal component analysis. The results showed that biomass-related traits such as fresh weight of shoot and leaf number had relatively high weights in the evaluation of salt and alkali tolerance at the seedling stage, and 38 highly saline-alkali tolerant materials were identified. A total of 242 SNPs affecting seedling saline-alkali tolerance were identified in a genome-wide association study of 240 faba bean accessions, with 57 SNPs significantly associated with 7 traits and identified by GLM and MLM models. It was found that 10 genes (such as L-GalLDH , ZAT4 , GA20ox2 ) overlapped with the reported genes related to salt-alkali tolerance or stress resistance by functional annotation of candidate genes. Conclusions: Which enhanced our understanding of the regulatory network of saline-alkali tolerance in faba beans and provided genetic resources and potential targets for molecular design breeding of saline-alkali tolerance in faba bean.