SNP association analysis of resistance to Verticillium wilt (Verticillium dahliae Kleb.) in spinach

Abstract

Verticillium wilt, caused by Verticillium dahliae Kleb., is an important disease of spinach (Spinacia oleracea L.) and use of genetic resistance is the most economical method of controlling this disease. The objective of this research was to conduct molecular association analysis for Verticillium wilt resistance in spinach. A total of 95 USDA spinach accessions were evaluated for resistance to Verticillium wilt in this study. Phenotyping was conducted using a 0-4 scale of disease severity scores of Verticillium wilt and genotyping was performed using 2,878 SNPs which were postulated from genotyping by sequencing (GBS). STRUCTURE 2.3.4 and MEGA 6 were used for population structure and genetic diversity analysis. The single marker regression (SMR) from QGene, general linear mode (GLM) and mixed linear mode (MLM) from TEASSEL, and compressed mixed linear model (cMLM) and enriched compressed mixed linear model (EcMLM) from GAPIT were used for association analysis of Verticillium wilt resistance. Significant genetic variation of Verticillium wilt disease resistance was observed among the 95 spinach accessions with a wide range from 0.3 to 3.0 on a 0-4 scale. Two well-differentiated genetic populations and admixtures were postulated in the spinach panel. Five SNP markers, AYZV02052595_108, AYZV02112284_14543, AYZV02123399_146, AYZV02164612_331, and AYZV02170942_274 were identified to be associated with Verticillium wilt resistance with R-squared values from 9.3 to 18.2%. These markers may provide a tool utilized in molecular spinach breeding to select Verticillium wilt resistance through marker-assisted selection.