Presence of a Sexual Population of Puccinia graminis f. Sp. Tritici in Georgia Provides a Hotspot for Genotypic and Phenotypic Diversity

Pablo D. Olivera, Zoya Sikharulidze, Rusudan Dumbadze, Les J. Szabo, Maria Newcomb, Ketino Natsarishvili, Matthew N. Rouse, Douglas G. Luster, Yue Jin

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a reemerging disease exemplified by recent epidemics caused by new virulent races. Understanding the sources and origins of genetic variations in the pathogen populations globally can facilitate the development of better strategies in disease management. We analyzed 68 wheat stem rust samples collected between 2013 and 2015 from Georgia where stem rust incidences are frequent and the alternate host, common barberry, is present. A total of 116 single-pustule isolates were derived and evaluated on stem rust differential lines to determine the virulence phenotypes and 23 races were identified, many of which were detected for the first time. Unique virulence combinations including, Sr22+Sr24 and Sr13b+Sr35+Sr37 were detected. These virulence combinations pose new challenges to breeding programs because many of these genes are used in breeding for resistance to the Ug99 race group. Sixty-one isolates were genotyped using a custom single-nucleotide polymorphism chip and 17 genotypes were identified. The 2013 isolates contained 11 multilocus genotypes compared with isolates of 2014 and 2015, with five and three genotypes, respectively. The higher levels of virulence and genotypic diversity observed in the 2013 samples strongly indicated that sexual recombination occurs in the Georgian P. graminis f. sp. tritici population, and that the Caucasus region of Eurasia may be an important source of new races.

Original languageEnglish (US)
Pages (from-to)2152-2160
Number of pages9
JournalPhytopathology
Volume109
Issue number12
DOIs
StatePublished - 2019

Bibliographical note

Funding Information:
Funding: This research was funded by United States Department of Agriculture-Agricultural Research Service and the Durable Rust Resistance in Wheat and Delivering Genetic Gain in Wheat projects administrated by Cornell University (grants DRRW-OPPGD1389 and DGGW-OPP1133199 were funded by the Bill and Melinda Gates Foundation and the United Kingdom Department for International Development). Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. The USDA is an equal opportunity provider and employer.

Funding Information:
This research was funded by United States Department of Agriculture-Agricultural Research Service and the Durable Rust Resistance in Wheat and Delivering Genetic Gain in Wheat projects administrated by Cornell University (grants DRRW-OPPGD1389 and DGGW-OPP1133199 were funded by the Bill and Melinda Gates Foundation and the United Kingdom Department for International Development). Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. The USDA is an equal opportunity provider and employer.

Publisher Copyright:
Copyright © 2019 The Author(s).

Keywords

  • Ecology and epidemiology
  • Genetics and resistance
  • Genotyping
  • Population biology
  • Race typing
  • Surveillance
  • Wheat stem rust

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