Fine-mapping of the Fusarium head blight resistance QTL Qfhs.ifa-5A identifies two resistance QTL associated with anther extrusion

Abstract

Key message Fine-mapping separated Qfhs.ifa-5A into a major QTL mapping across the centromere and a minor effect QTL positioned at the distal half of 5AS. Both increase Fusarium resistance and anther extrusion. Abstract The Fusarium head blight (FHB) resistance QTL Qfhs.ifa - 5A resides in the low-recombinogenic pericentromeric region of chromosome 5A making fine-mapping particularly arduous. Qfhs.ifa - 5A primarily contributes resistance to fungal entry with the favorable allele descending from the highly Fusarium resistant cultivar Sumai-3. Fine-mapping a near-isogenic recombinant inbred line population partitioned the Qfhs.ifa - 5A interval into 12 bins. Near-isogenic lines recombining at the interval were phenotyped for FHB severity, anther retention and plant height. Composite interval mapping separated the initially single QTL into two QTL. The major effect QTL Qfhs.ifa - 5Ac mapped across the centromere and the smaller effect QTL Qfhs.ifa - 5AS mapped to the distal half of 5AS. Although Qfhs.ifa - 5Ac and Qfhs.ifa - 5AS intervals were as small as 0.1 and 0.2 cM, their corresponding physical distances were large, comprising 44.1 Mbp and 49.2 Mbp, respectively. Sumai-3 alleles at either QTL improved FHB resistance and increased anther extrusion suggesting a pleiotropic effect of anthers on resistance. This hypothesis was supported by greenhouse experiments using the susceptible cultivar Remus and its resistant near-isogenic line NIL3 carrying the entire Qfhs.ifa - 5A segment. By manually removing anthers prior to spray inoculation both, Remus and NIL3 became almost equally resistant in the early phase of the disease development and were significantly less diseased than variants without anther manipulation. At late time points the positive effect of the anther removal became smaller for Remus and disappeared completely for NIL3. Results affirm that absence of anthers enhanced resistance to initial infection but did not protect plants from fungal spreading within spikes. Electronic supplementary material The online version of this article (10.1007/s00122-019-03336-x) contains supplementary material, which is available to authorized users.

Relationship between genetic variability of flowering traits andFusariummycotoxin contamination in oats

“…Results of Panel 2 and Panel 3 displayed that complete cleistogamy, as found in cultivar Aveia, or a high level of chasmogamy, such as in Schenkenfeldener, resulted in lower infection levels and mycotoxin accumulation, but there are several known and unknown factors interfering with AR and mycotoxin accumulation. A precise evaluation of the impact of AR on mycotoxin content will require tests in oat populations with less variation in PH and flowering date, but high variability in AR, as recently used in wheat (Steiner et al, 2019). Our results indicate that differences in AR in oats explained only a small part of genetic variability for resistance to Fusarium, and more research is needed to disassemble and depict the active and passive resistance components against Fusarium in this smallgrain cereal.…”

“…Since oats are most susceptible to Fusarium infection during flowering (Tekle et al, 2012;Xue et al, 2015), and also because of the colocation of QTLs for AR and FHB in wheat (Steiner et al, 2019), a significant effect of AR on mycotoxin accumulation in oats was hypothesized. Results of Panel 2 and Panel 3 displayed that complete cleistogamy, as found in cultivar Aveia, or a high level of chasmogamy, such as in Schenkenfeldener, resulted in lower infection levels and mycotoxin accumulation, but there are several known and unknown factors interfering with AR and mycotoxin accumulation.…”

Fusarium Head Blight, Mycotoxins and Strategies for Their Reduction

“…It is now possible to identify genomic regions that contain genes, referred to as quantitative trait loci (QTLs) and single nucleotide polymorphism markers for FHB resistance derived from QTL mapping and genome-wide association studies. Ultimately, this will contribute to the selection of genotypes and cultivation of plants resistant to mycotoxin-producing pathogens [166,176].…”

Anther Extrusion and Its Association with Fusarium Head Blight in CIMMYT Wheat Germplasm

“…In the aforementioned studies, numerous QTL for AE were identified, and many of them were reported to be responsible for both AE and FHB [4,5,9,33]. In this regard, the well-known ones are those on 4BS and 4DS, linking to Rht-B1 and Rht-D1 [9], respectively, as well as the closely linked ones on 5AS and 5Ac in the Fhb5 region [5,34]. Considering the close relationship of AE with Type I FHB resistance, the former was proposed as a morphological marker for FHB resistance by many researchers [4,10].…”