Abstract
Developing and deploying multi-use naked barley varieties that accumulate lower levels of deoxynivalenol (DON) resulting from Fusarium head blight (FHB) disease could help farmers mitigate economic risks and expand market possibilities. Previous work established that a substantial amount of DON in covered barley accumulates in the hull and can be removed by pearling. We studied a diverse panel of 244 naked barley lines to determine if there is a genetic variation for the distribution of DON in Fusarium-infected spikes. We evaluated the panel genotyped with a 50K Barley SNP array for disease severity, toxin accumulation, and other agronomic traits in two FHB disease nurseries from 2020 to 2021. Harvested naked barley spikes separated into hull and kernel fractions revealed that 11.92-70.02% of the total toxins were localized in the hull. Single-SNP and haplotype-based genome-wide association studies (GWAS) were carried out using mixed linear models. Based on the single-SNP GWAS, 132 marker-trait associations, localized into 13 quantitative trait loci, were identified for all the traits except FHB severity. Haplotype-based GWAS found two haplotype-trait associations each for DON in hull and plant height, three for DON in rachis, and five for heading date. Notably, markers and haplotypes associated with later heading were also linked to higher levels of the toxin in the hull but not the kernel. Moderate-to-high predictive abilities suggest that genomic selection could be used to develop improved naked barley cultivars with a lower risk of DON contamination.