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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #339844
Title: Genetic differentiation of the wheat leaf rust fungus Puccinia triticina in Pakistan and genetic relationship to other worldwide populations

Author
item Kolmer, James
item MIRZA, JAVED - Cereal Crops Research Institute
item IMTIAZ,, MUHAMMAD - International Maize & Wheat Improvement Center (CIMMYT)
item SHAH,, JAWAD - Nuclear Institute For Food And Agriculture (NIFA)

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2017
Publication Date: 6/1/2017
Citation: Kolmer, J.A., Mirza, J.I., Imtiaz, M., Shah, J.A. 2017. Genetic differentiation of the wheat leaf rust fungus Puccinia triticina in Pakistan and genetic relationship to other worldwide populations. Phytopathology. 107(6):786-790.

Interpretive Summary: Wheat is attacked by a fungus that is called Puccinia triticina, which is the scientific name of the fungus that causes the disease wheat leaf rust. This disease occurs in the U.S. and world wide. This study examined the Puccinia triticina population in Pakistan as part of a worldwide study of genetic variation in this fungus. Twenty-four different races of the leaf rust fungus were described in Pakistan. Most of the races had virulence to important leaf rust resistance genes in wheat cultivars that are grown in Pakistan. Three major groups of isolates were described using DNA based molecular markers. Some of the leaf rust isolates from Pakistan had the same virulence and molecular markers as isolates in the United States, South America, and Europe, which indicated a recent migration of these isolates worldwide. This information can be used by wheat breeders and plant pathologists to develop wheat cultivars with improved leaf rust resistance.

Technical Abstract: Collections of Puccinia triticina, the wheat leaf rust pathogen, were obtained from Pakistan in 2008, 2010, 2011, 2013, and 2014. Collections were also obtained from Bhutan in 2013. Single uredinial isolates were derived and tested for virulence phenotype to 20 lines of Thatcher wheat that differ for single leaf rust resistance genes, and for molecular genotype with 23 simple sequence repeat (SSR) primers. Twenty-four virulence phenotypes were described among the 89 isolates tested for virulence. None of the isolates had virulence to Thatcher lines with Lr9, Lr24, or Lr18. Virulence to most of the other Thatcher lines was over 50%. The two most common virulence phenotypes, FHPSQ and KHPQQ had virulence to Lr16, Lr17, and Lr26. Twenty-seven SSR genotypes were found among the 43 isolates tested for molecular variation. The SSR genotypes had high levels of observed heterozygosity and significant correlation with virulence phenotype, that indicated clonal reproduction. Cluster analysis and principal component plots indicated three groups of SSR genotypes that also varied significantly for virulence. Isolates with MBDSS and MCDSS virulence phenotypes from Pakistan and Bhutan were highly related for SSR genotype and virulence to isolates from Turkey, Europe, Central Asia, the Middle East, North America and South America, indicating the possible migration of the rust fungus between continental regions.