Identification of Blast Resistance Genes in Aegilops tauschii and Triticum aestivum.

O’Hara, Thomas (2023) Identification of Blast Resistance Genes in Aegilops tauschii and Triticum aestivum. Doctoral thesis, University of East Anglia.

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As the world’s most widely grown crop, wheat contributes to 20% of the daily protein and calorie intake for 4.5 billion people. Wheat blast disease, caused by the fungal pathogen Magnaporthe oryzae pv. tritici (MoT), is a relatively recent disease threatening global wheat production. In February 2016, wheat blast made the headlines with a severe outbreak reported in Bangladesh. The presence of wheat blast in Bangladesh is of immense concern as it could act as a gateway for wheat blast to spread throughout South Asia. Despite continuous breeding efforts over the past 30 years to improve blast resistance in wheat, only a handful of resistance genes have been discovered. Moreover, wheat blast resistance has been overcome in some regions in Brazil. It is therefore crucial that new resistance genes are discovered to control this devastating disease. Crop wild relative species are potential sources of novel resistances, as they often have greater genetic variation than cultivated crops.

The resistance genes Rmg7 and Rmg8 map to 2A and 2B respectively in wheat and both recognise the Avr-Rmg8 effector. In the present study, a rapid GWAS based gene cloning approach was used to identify D genome resistance against the Avr-Rmg8 effector using a diversity panel of Aegilops tauschii, the D genome progenitor of hexaploid wheat. An association spanning 162kb on chromosome 7D, containing seven candidates in the resistant haplotype was investigated. Landraces also capture genetic diversity lost through breeding. Similar methods were used to exploit the genetic diversity within 320 Watkins landrace accessions. This resulted in the identification and validation of a serine/threonine kinase as Rmg7; the first R gene cloned for wheat blast. The gene was identical to the race specific gene wheat powdery mildew (Blumeria graminis f.sp. tritici) gene Pm4. The work carried out within this study demonstrates the power of combining genome-based GWAS with isolate-specific phenotyping in the identification of loci and genes conferring resistance to MoT.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 30 Jan 2024 13:07
Last Modified: 30 Jan 2024 13:07

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