CBGG

Grain yield is the primary target for increasing soft red winter wheat production in the United States. Genome wide association studies were performed for yield-related traits using field-based evaluation of 270 elite breeding lines. Yield ranged from 3.9 to 7.5 tons·ha−1. The effect of genotype by year interaction was significant for most traits. Heritability estimates ranged from 0.21 for biomass to 0.84 for plant height. Biomass, kernel weight, and grain weight per spike were positively correlated with grain yield while days to heading and maturity were negatively correlated with grain yield. We used FarmCPU method and 45K markers to identify marker-trait associations. Fifty-nine MTAs were identified based on two-year phenotypic estimates. An association for grain yield on chromosome 7D showed a −logP value of 16.35 and explained 18% of the phenotypic variation. Associations were identified at −logP values of 6.30 and 4.08 on chromosomes 5A for thousand kernel weight and grain per spike that explained 10% and 6% of phenotypic variations, respectively. Grain yield and days to heading data from previous trials in other states were used to validate and evaluate the transferability of associations. We observed that for grain yield, only 7 out of 28 associations and for days to heading, only 8 out of 47 associations were validated across seemingly homogenous environments, indicating the majority of associations are not stable QTL across environments. This study suggests that achieving genetic gains appears to require utilizing genotype by environment interaction and local field based germplasm testing.

wheat; genome wide association studies; marker trait associations; yield components; grain yield; days to heading