Genome-wide association study of turnip mosaic virus resistance in non-heading Chinese cabbage

A genome-wide association study (GWAS) using 83 diverse non-heading Chinese cabbage (NHCC) accessions identified 42,526 high-quality single nucleotide polymorphism markers associated with turnip mosaic virus (TuMV) resistance. Seventeen associated loci were identified, along with the related genes that were differentially expressed between resistant and susceptible varieties, suggesting that they may be candidate genes for TuMV tolerance. Nine mutant genes of Arabidopsis were selected for inoculation with TuMV-GFP (green fluorescence protein) to further confirm the disease resistance of these genes. Quantitative polymerase chain reaction (qPCR) analysis showed that the virus content in the Arabidopsis mutants with the homologous genes of cell wall-associated proteins, pectin methyl-esterase (PME), transcription factors (TFs), resistance gene (R), VAN3/SFC protein and F-box gene were significantly higher than that in the mutants with the homologous genes of methylation and J protein. Our results provide the basis of further study of the potential function of these candidate TuMV resistance genes and demonstrate that the described diverse NHCC can be efficiently used for GWAS of various quantitative traits. Taken together, the findings of this study will be useful to improve TuMV resistance in NHCC breeding and to discover new genes related to TuMV resistance.