Using virulence mutants to Identify Avr genes in the wheat stem rust fungus, Puccinia graminis f. sp. tritici

C2 - Non-edited contributions to conferences

Upadhyaya, N. M., Ortiz, D., Chen, J., Ellis, J., Li, F., Mago, R., Kanyuka, K., Figueroa, M., Park, R. F. and Dodds, P. 2018. Using virulence mutants to Identify Avr genes in the wheat stem rust fungus, Puccinia graminis f. sp. tritici. International Congress of Plant Pathology (ICPP) 2018. Boston, USA 29 Jul 2018 American Phytopathological Society (APS).

AuthorsUpadhyaya, N. M., Ortiz, D., Chen, J., Ellis, J., Li, F., Mago, R., Kanyuka, K., Figueroa, M., Park, R. F. and Dodds, P.
TypeC2 - Non-edited contributions to conferences
Abstract

The wheat stem rust fungus Puccinia graminis f. sp. tritici (Pgt) is one of the most destructive pathogens of wheat. Resistance of host lines is often governed by recognition of fungal effector proteins (avirulence/virulence proteins) by plant resistance proteins (R proteins). We have taken a mutational genomics approach to identify Avr genes in Pgt. We isolated spontaneous mutants with virulence for Sr50, Sr5, Sr27, Sr21 or Sr45 by selection on resistant host lines. Sequence analysis of the Sr50 virulent mutant revealed that virulence resulted from the exchange of a whole chromosome between the two haploid nuclei of this dikaryotic organism, resulting in loss of the avirulence allele. This confirms the important role of somatic exchange events in virulence evolution in Pgt. The AvrSr50 gene was identified from the 25 candidate effector genes from this chromosome by transient co-expression with the cloned Sr50 gene in N. benthamiana. AvrSr50 recognition was confirmed in wheat by viral expression. AvrSr50 is expressed early during infection and is highly expressed in haustoria. Three mutants with virulence for Sr27 contain overlapping deletions and a single candidate gene for AvrSr27 has been identified. Likewise, AvrSr5 mutants contain large deletions spanning several candidate effector genes. New expression assays are being developed for confirmation of avirulence gene function in wheat.

Keywords
Year of Publication2018
Conference titlePlant Health In A Global Economy
Conference locationBoston, USA
Event date29 Jul 2018
03 Aug 2018
Digital Object Identifier (DOI)doi:10.1094/PHYTO-108-10-S1.1
Open accessPublished as green open access
Accepted author manuscriptUpadhyaya.pdf
JournalPhytopathology
Journal citation108 (S1.1)
PublisherAmerican Phytopathological Society (APS)
Book editorAmerican Phytopathological Society (APS) Press
Funder project or codeDesigning Future Wheat (DFW) [ISPG]
DFW - Designing Future Wheat - Work package 2 (WP2) - Added value and resilience
FunderBiotechnology and Biological Sciences Research Council
Output statusPublished
Publication dates
Online15 Oct 2018
Publication process dates
Accepted2018
Copyright licenseCC BY
ISSN0031-949X

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