Investigating Fusarium resistance in UK winter oats
Blackshaw-Crosby, J. (2022) Investigating Fusarium resistance in UK winter oats. Doctoral thesis, Harper Adams University.
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Abstract
The European Union is currently drafting legislation for maximum limits of the mycotoxins HT2 and T2 in cereals and cereal products intended for human consumption. Fusarium langsethiae has been identified as the main HT2+T2 mycotoxin producer in UK oats. Until the discovery of high concentrations of HT2+T2 in UK oats, oats were considered largely resistant to Fusarium infection. Strong evidence of the epidemiology of the pathogen is still lacking, the infection is symptomless and as, yet no sexual stage has been observed. Cultivars have been demonstrated to have varying resistances to the accumulation of HT2+T2 with ranking remaining relatively consistent across years. This work sought to further clarify the resistance imparted on oat plants by the parental origin of four quantitative trait loci (QTL) identified previously as being associated with F. langsethiae DNA and HT2 +T2 concentration in harvested oat grains. The QTL are designated Mrg04, Mrg20, Mrg21 and Mrg11 and were examined using near isogenic lines (NIL) developed from a mapping population derived from crossing Tardis (a taller earlier cultivar) and Buffalo (a semi-dwarf later cultivar). Introgression of the Buffalo derived Mrg04 QTL into the Tardis background resulted in a shorter plant with only panicles only partially emerged from the flag leaf boot. The opposite introgression lead to plant taller than either parent line. Introgression of the Tardis Mrg21 into the Buffalo background resulted in a later plant when sown in autumn, the effect was close to tenfold when sown in spring. The introgression of the Buffalo Mrg21 into the Tardis background caused the resultant plant to be earlier in autumn sown plots and four times as much so in spring sown plots. Buffalo is the more susceptible of the two cultivars to F. langsethiae. Through comparison of the NIL with original parent lines reductions in HT2+T2 concentrations were seen when Tardis Mrg04 and Mrg21 alleles were introgressed into the Buffalo background genome. The impact of Mrg04 was consistent across all experiments whilst the impact of Mrg21 was dependant on sowing season. The Mrg21 QTL had a weaker effect compared to Mrg04 but introgression of the Buffalo alleles into the Tardis background resulted in a reduction of HT2+T2 in autumn sown plots. Introgression of Tardis derived Mrg20 into Buffalo had no impact on the HT2+T2 concentration, and introgression of Buffalo derived Mrg20 into Tardis had inconsistent effects across years. Successful artificial inoculation of the NIL was achieved under glass, but the ranking of the NIL did not match that of the naturally infected field grown plots. Artificial inoculation attempted in field experiments failed to achieve higher infection levels than uninoculated plots. Plant height and panicle extrusion were correlated to one another, and evidence is presented that either or both could be influencing plant susceptibility to F. langsethiae infection. Dissection of naturally infected panicles and quantification of F. langsethiae DNA concentration at the spikelet level demonstrated the independent nature of the infection in each spikelet reinforcing previous work that oats have high type II resistance to Fusarium infection. Window-pane analysis of summarised environmental variables utilising the NIL field experiments over four years demonstrated that the warm dry conditions post panicle emergence are conducive to higher HT2+T2 concentrations in harvested oats.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Divisions: | Agriculture and Environment (from 1.08.20) |
| Depositing User: | Ms Kath Osborn |
| Date Deposited: | 28 Jun 2022 15:12 |
| Last Modified: | 28 Jun 2022 15:12 |
| URI: | https://hau.repository.guildhe.ac.uk/id/eprint/17857 |
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