Associations between morphological and FHB traits in a soft red winter wheat population

Fusarium head blight (FHB) is a destructive disease in wheat (Triticum aestivum) and other small grains. Morphological traits can act as barrier between pathogen and plant and provide a passive form of resistance to disease. The objectives were: (1) to phenotype 250 soft red winter wheat (SRWW) breeding lines and cultivars for morphological traits in 2015-2016; (2) to estimate their correlations with disease resistance; and (3) to identify QTL for morphological traits associated with FHB resistance through genome-wide association study (GWAS). Morphological traits measured were anther extrusion, plant height, peduncle length, spike length (SL), spikelet number (SN), spike density (SD), spike inclination (SI). Agronomic traits included heading date and yield. Disease traits were: FHB-rating, incidence, severity, FHB-index, Fusarium damaged kernels and deoxynivalenol (DON) concentration. There were significant (p < 0.01) differences among genotypes for all morphological traits measured. Moderate heritabilities (0.41-0.66) for spike traits were estimated. Morphological and disease traits were generally negatively correlated; e.g. there was a significant (p < 0.01) negative correlation between spike inclination and DON. GWAS identified 29 significant (p < 0.001) SNPs associated with morphological traits, ranging from - 3.54 to 9.58% of the trait mean. Potential SNPs for yield were located on chromosomes 1B, 3B and 6A. Despite the small effects identified for the SNPs, several morphological traits should be considered for phenotypic and/or genomic selection in FHB resistance breeding programs.