Multilocus genotypes of the wheat leaf rust fungus Puccinia triticina in worldwide regions indicate past and current long distance migration

Authors: Kolmer, James; ORDONEZ, MARIA - Pontifical Catholic University Of Ecuador; GERMAN, SILVIA - National Agricultural Research Institute(INIA); MORGOUNOV, ALEXI - International Maize & Wheat Improvement Center (CIMMYT); PRETORIUS, ZACK - University Of The Free State; VISSER, BOTMA - University Of The Free State; GOYEAU, HENRIETTE - French National Institute For Agricultural Research; ANIKSTER, YEHOSHUA - Tel Aviv University; ACEVEDO, MARICELIS - Cornell University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2019
Publication Date: 4/1/2019
Citation: Kolmer, J.A., Ordonez, M.E., German, S., Morgounov, A., Pretorius, Z., Visser, B., Goyeau, H., Anikster, Y., Acevedo, M. 2019. Multilocus genotypes of the wheat leaf rust fungus Puccinia triticina in worldwide regions indicate past and current long distance migration. Phytopathology. https://doi.org/10.1094/phyto-10-18-0411-r.
DOI: https://doi.org/10.1094/phyto-10-18-0411-r

Interpretive Summary: Wheat is attacked by the rust fungus called Puccinia triticina, which causes the disease wheat leaf rust. There are many different forms or races of the wheat leaf rust fungus that vary in their ability to attack different resistance genes in wheat. Every year the USDA-ARS Cereal Disease Laboratory makes collections of the wheat leaf rust fungus from the major wheat growing regions of the United States to determine which forms of P. triticina are present. Collections of the leaf rust fungus were also made in different worldwide regions. The objective of this research was to determine the genetic relationship between worldwide populations of P. triticina with the population that is present in North America. DNA based molecular markers identified 424 different genotypes among 831 collections of P. triticina from 11 different wheat growing regions across the world. Twenty seven of the genotypes were found in more than one continental region, which indicated that these genotypes had migrated in the past between different continental regions. The results indicated that the leaf rust fungus is capable of long distance migration. The results will be useful for wheat breeders and plant pathologists in the development of leaf rust resistant wheat cultivars.

Technical Abstract: Many plant pathogenic fungi have a global distribution across diverse ecological zones and agricultural production systems. Puccinia triticina, the wheat leaf rust fungus, is a major pathogen in many wheat production areas of the world. The objective of this research was to determine the genetic relatedness of P. triticina in different worldwide regions. A total of 831 single uredinial isolates collected from 11 continental regions were characterized for multilocus genotype at 23 simple sequence repeat loci and for virulence to 20 lines of wheat with single genes for leaf rust resistance. A total of 424 multilocus genotypes and 497 virulence phenotypes were found. All populations had high heterozygosity and significant correlation between virulence and molecular variation, which indicated clonal reproduction. The populations from North America and South America; Central Asia and Russia; the Middle East and Europe were closely related for multilocus genotypes and many individual isolates from other continental regions were closely related. Twenty-seven multilocus genotypes were found in more than one continental region, and 13 of these had isolates with identical virulence phenotypes. The wide geographic distribution of identical and highly related multilocus genotypes of P. triticina indicated past and more recent migration events facilitated by the spread of clonally produced urediniospores.