Genetic Diversity and Resistance to Fusarium Head Blight in Synthetic Hexaploid Wheat Derived From Aegilops tauschii and Diverse Triticum turgidum Subspecies

Abstract

Synthetic hexaploid wheat (SHW) can serve as a bridge for the transfer of useful genes from Aegilops tauschii and tetraploid wheat (Triticum turgidum) into common wheat (T. aestivum). The objective of this study was to evaluate 149 SHW lines and their 74 tetraploid parents for their genetic diversity, breeding values and inter-genomic interactions for resistance to Fusarium head blight (FHB). The genetic diversity analysis was performed based on the population structure established using 4,674 and 3,330 polymorphic SNP markers among the SHW lines and tetraploid parents, respectively. The results showed that all T. carthlicum and most T. dicoccum accessions formed different clusters and subpopulations, respectively, whereas all the T. durum, T. polonicum, T. turgidum, and T. turanicum accessions were clustered together, suggesting that T. durum was more closely related to T. polonicum, T. turgidum, and T. turanicum than to T. dicoccum. The genetic diversity of the SHW lines mainly reflected that of the tetraploid parents. The SHW lines and their tetraploid parents were evaluated for reactions to FHB in two greenhouse seasons and at two field nurseries for 2 years. As expected, most of the SHW lines were more resistant than their tetraploid parents in all environments. The FHB severities of the SHW lines varied greatly depending on the Ae. tauschii and tetraploid genotypes involved. Most of the SHW lines with a high level of FHB resistance were generally derived from the tetraploid accessions with a high level of FHB resistance. Among the 149 SHW lines, 140 were developed by using three Ae. tauschii accessions CIae 26, PI 268210, and RL 5286. These SHW lines showed FHB severities reduced by 21.7%, 17.3%, and 11.5%, respectively, with an average reduction of 18.3%, as compared to the tetraploid parents, suggesting that the D genome may play a major role in reducing disease severity in the SHW lines. Thirteen SHW lines consistently showed a high level of FHB resistance compared to the resistant check, Sumai 3, in each environment. These SHW lines will be useful for the development of FHB-resistant wheat germplasm and populations for discovery of novel FHB resistance genes.

Epigenetic regulation of gene expression improves Fusarium head blight resistance in durum wheat

“…Except a few variations, the performances of selected lines were consistent and the results were reproducible. The variation in FHB resistance in the M4 lines or in the parental lines observed during this study can be attributed to variability in FHB reactions, unfavorable environmental conditions for disease development or escape from inoculation which commonly occur in field FHB evaluation as documented by other researchers 43 – 45 . Stability and inheritance of resistance of M4 lines were further tested by crossing two M4 lines (E.25.11 and 41,708.72) with a susceptible parental line, Ben and developing BC 1 :F 3 families and testing them by Fusarium inoculation, which confirmed that the modification is stable, genetic and heritable.…”

Breeding for Fusarium head blight resistance in wheat—Progress and challenges

“…A possible explanation could be that current durum wheat, mostly descending from germplasm of the warm and summer‐dry Mediterranean basin, has not been exposed to relevant disease pressure and selection for improved FHB resistance had historically low priority (Buerstmayr et al, ). It is also hypothesized that the D genome of hexaploid wheat may play a major role in reducing disease severity as synthetic wheat lines, generated by crossing tetraploid T. turgidum with Aegilops tauschii , were more resistant than the T. turgidum parents (Szabo‐Hever et al, ).…”

Exploring the alpha‐gliadin locus: the 33‐mer peptide with six overlapping coeliac disease epitopes in Triticum aestivum is derived from a subgroup of Aegilops tauschii

“…durum with A. tauschii accessions, followed by chemical chromosome doubling. These so‐called re‐synthesised bread wheats or synthetic hexaploid wheats (SHWs) are made with the goal of introducing new functional trait diversity into modern germplasm (Kishii, 2019), notably disease resistance genes (Mujeeb‐Kazi et al ., 1996; Das et al ., 2016; Szabo‐Hever et al ., 2018; Kishii et al ., 2019; Mohler et al ., 2020) but also, for example, a higher yield (Hao et al ., 2019). The International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico has been developing many synthetic hexaploid wheats since the 1960s (Gordon et al ., 2019), but several other programmes exist, for example at NIAB, Cambridge, UK.…”