Effective marker alleles associated with type 2 resistance to Fusarium head blight infection in fields

Abstract

Molecular markers associated with known quantitative trait loci (QTLs) for type 2 resistance to Fusarium head blight (FHB) in bi-parental mapping population usually have more than two alleles in breeding populations. Therefore, understanding the association of each allele with FHB response is particularly important to marker-assisted enhancement of FHB resistance. In this paper, we evaluated FHB severities of 192 wheat accessions including landraces and commercial varieties in three field growing seasons, and genotyped this panel with 364 genome-wide informative molecular markers. Among them, 11 markers showed reproducible marker-trait association (p < 0.05) in at least two experiments using a mixed model. More than two alleles were identified per significant marker locus. These alleles were classified into favorable, unfavorable and neutral alleles according to the normalized genotypic values. The distributions of effective alleles at these loci in each wheat accession were characterized. Mean FHB severities increased with decreased number of favorable alleles at the reproducible loci. Chinese wheat landraces and Japanese accessions have more favorable alleles at the majority of the reproducible marker loci. FHB resistance levels of varieties can be greatly improved by introduction of these favorable alleles and removal of unfavorable alleles simultaneously at these QTL-linked marker loci.

Fusarium Head Blight and Rust Diseases in Soft Red Winter Wheat in the Southeast United States: State of the Art, Challenges and Future Perspective for Breeding

“…However, it is often questionable whether markers can be validated in a diverse background to enhance the visibility of the QTL mapping results. Nonetheless, Li et al (2016a) observed very few markers (~3%) holding reproducible marker-trait association while testing 364 genome-wide informative SSR and sequence-tagged site (STS) markers associated with type II FHB resistance. Additionally, Petersen et al (2017) found that only one QTL ( Qfhb.nc-2B.1 ) and its associated marker contributed resistance to disease severity and FDK and was identified as the best candidate for use in MAS among twelve genomic loci identified from diverse wheat nurseries.…”

Genome-wide association mapping revealed syntenic loci QFhb-4AL and QFhb-5DL for Fusarium head blight resistance in common wheat (Triticum aestivum L.)

“…The average percentage of symptomatic spikelets (PSS) was calculated as the measure of FHB severity. All tested accessions were classified into four classes based on FHB severity, resistant (0 < PSS ≤25%), moderately resistant (25% < PSS ≤50%), moderately susceptible (50% < PSS ≤75%) and susceptible (75% < PSS ≤ 100%) [51].…”

Genetic Characterization of a Wheat Association Mapping Panel Relevant to Brazilian Breeding Using a High-Density Single Nucleotide Polymorphism Array

“…Previous GWAS studies have identified genetic loci controlling FHB (e.g., Wang et al 2017) and awning (e.g., DeWitt et al 2019) (for further examples, see also Discussion). As a complementary approach to the use of high-density genotyping approaches, the availability of genetic markers diagnostic or highly predictive of allelic state at genetic loci controlling major agronomic traits in wheat (e.g., those listed on CerealsDB, https:// www.cerealsdb.uk.net/cerealgenomics/, and subsequently published by Rasheed et al 2016) allow known loci to be rapidly characterized in breeder-relevant germplasm, including association mapping panels (e.g., Li et al 2016). Despite the potential for such marker-informed approaches, relatively limited genome-wide genotypic investigation of Brazilian wheat germplasm has been undertaken to date (Schuster et al 2009).…”