Genome-wide association mapping and characterization of genetic loci associated with resistance against wheat streak mosaic virus.

BACKGROUND

Wheat streak mosaic disease, caused by wheat streak mosaic virus (WSMV), is considered a serious cereal disease that threatens wheat yield worldwide. To date, only a limited number of genes related to WSMV resistance have been characterized. Identification of novel sources of resistance is essential for the development of resistant varieties.

RESULTS

In this study a genome-wide association study (GWAS) and expression analysis of candidate QTLs through RT-qPCR were implemented on a set of 175 globally diverse wheat genotypes. A GWAS of 21,773 high-quality DArTseq markers revealed 17 significant markers (p-value < 10- 4, and FDR < 0.05) on chromosomes 1B, 2 A, 2B, 2D, 3 A, 3B, 4B, 5 A, 5B, 6 A, 6B, 6D and 7 A. GWAS results revealed some potential candidate genes for WSMV resistance, including several nucleotide binding site-leucine-rich repeats (NBS-LRR)-type resistance genes, different types of kinases such as serine-threonine/tyrosine-protein kinase and defense-related proteins such as F-box proteins (FBPs), GroEL-like heat shock protein 60 and cytochrome P450. Moreover, comparisons of the expression profiles of eight candidate genes between two accession, resistant (the landrace IPK41079) and susceptible (the cultivar Alamut), using RT-qPCR revealed higher relative expression levels in resistant than susceptible accessions.

CONCLUSIONS

These candidate genes and associated QTLs represent promising targets for marker-assisted selection (MAS) following independent validation in additional wheat populations and field environments.