Molecular Characterization and Expression of PFT, an FHB Resistance Gene at the Fhb1 QTL in Wheat

Abstract

Fusarium head blight (FHB) is a destructive fungal disease in wheat worldwide. Efforts have been carried out to combat this disease, and the pore-forming toxin-like (PFT) gene at the quantitative trait locus (QTL) Fhb1 was isolated and found to confer resistance to FHB in Sumai 3. In this study, we characterized PFT in 348 wheat accessions. Four haplotypes of PFT were identified. The wild haplotype of PFT had higher resistance than other haplotypes and explained 13.8% of phenotypic variation in FHB resistance by association analysis. PFT was highly expressed during early flowering and increased after Fusarium graminearum treatment in Sumai 3. Analysis of the 5' flanking sequence of PFT predicted that the cis elements of the PFT promoter were related to hormones and biological defense responses. However, PFT existed not only in the FHB-resistant accessions but also in some susceptible accessions. These results suggested that FHB resistance in a diverse range of wheat genotypes is partially conditioned by PFT. The profiling of FHB resistance and the PFT locus in this large collection of wheat germplasm may prove helpful for incorporating FHB resistance into wheat breeding programs, although more work is needed to reveal the exact role of the QTL Fhb1 in conferring resistance to fungal spread.

Exploring and exploiting the genetic variation of Fusarium head blight resistance for genomic-assisted breeding in the elite durum wheat gene pool

“…Notably, only the susceptible Syrian landrace ‘Haurani’ possessed the ‘resistant’ PFT haplotype that is in contrast to a study of 40 wheat landraces and cultivars where the PFT allele was exclusively found in FHB resistant lines (Rawat et al 2016 ). In a broader study of 348 hexaploid wheat accessions of mainly Chinese origin, the ‘resistant’ PFT allele existed also in susceptible accessions (He et al 2018 ) and in a collection of 151 cultivars 44 lines were positive for the Wangshuibai/Sumai-3 PFT allele, but only 12 of them were resistant (Jia et al 2018 ). Fhb1 has been introgressed in hexaploid wheat and durum wheat, mostly efficiently improved FHB resistance levels but the recurrent parent had a large impact on the effect of Fhb1 suggesting a large dependency on the genetic background (Von der Ohe et al 2010 ; Salameh et al 2011 ; Balut et al 2013 ; Prat et al 2017 ).…”

Optical Sorter-Based Selection Effectively Identifies Soft Red Winter Wheat Breeding Lines With Fhb1 and Enhances FHB Resistance in Lines With and Without Fhb1

“…Optical sorter-based selection operated on detectable differences in seed color only, not seed shape/size or preharvest appearance of the plant. Furthermore, previous research has shown the QTL on 5A contributes mostly to Type I resistance, unlike Fhb1 which contributes to strong Type II resistance (Bai et al, 1999;Buerstmayr et al, 2003;He et al, 2018;Steiner et al, 2019). Therefore, Qfhs.ifa-5A may be more involved in reducing physical kernel damage (shriveled seeds/FDK) and visible preharvest disease symptoms (rating), than differences in seed coat color as a result of FHB infection (FDKos).…”

“…The majority of major effect QTL detected for reduced DON accumulation, including Fhb1, co-located with QTL for reduced disease severity on plants preharvest or grains postharvest (Somers et al, 2003;Liu et al, 2012;Liu et al, 2013;Ágnes et al, 2014;Buerstmayr and Lemmens, 2015). Furthermore, Fhb1 has been classified as a strong contributor to Type II FHB resistance, which is associated with reductions in Fusarium damaged kernels (Bai et al, 1999;He et al, 2018). The proportion of Fusarium damaged kernels determined with an optical sorter (FDKos) is a postharvest measure of disease severity on grain as well as an indicator of Type II FHB resistance; therefore, it is not surprising that optical sorter-based among line selection (lines with FDKos values greater than the resistant check were discarded each selection cycle) increased the proportion of lines with Fhb1 (a QTL known to be associated with reduced kernel damage).…”

“…Fhb1 was first described by Waldron et al as Qfhs.ndsu-3B and later renamed (Waldron et al, 1999;Liu et al, 2006;Agostinelli et al, 2011). Fhb1 is a major effect QTL that confers strong Type II resistance to FHB in wheat and other small grains (Bai et al, 1999;Cuthbert et al, 2006;Petersen et al, 2017;Steiner et al, 2017;He et al, 2018;Zhu et al, 2019). Qfhs.ifa-5A contributes mainly to Type I FHB resistance (Buerstmayr et al, 2003;Steiner et al, 2019).…”

Breeding for the resistance to Fusarium head blight of wheat in China

“…Rawat et al [105] reported a pore-forming, toxin-like domain conferring FHB resistance for Fhb1. However, markers based on the SNP of this gene do not readily allow the distinction of FHB resistance or susceptible lines when hundreds of lines are assessed [106] . Based on sequencing of the Fhb1 region of near-isogenic lines, fragment deletions and SNP variations of His (histidine-rich calcium binding protein) gene have been identified, and most of the materials lacking 752 bp fragments were scab resistant materials.…”