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Location: Cereal Disease Lab

Title: Genetically divergent types of the wheat leaf fungus Puccinia triticina in Ethiopia, a center of tetraploid wheat diversity

item Kolmer, James - Jim
item ACEVEDO, M - North Dakota State University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/25/2015
Publication Date: 4/1/2016
Citation: Kolmer, J.A., Acevedo, M.A. 2016. Genetically divergent types of the wheat leaf fungus Puccinia triticina in Ethiopia, a center of tetraploid wheat diversity. Phytopathology. 106(4):380-385. doi: 10.1094/PHYTO-10-15-0247-R.

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 Ethiopia as part of a worldwide study of genetic variation in this fungus. In Ethiopia the wheat population is very unique as old collections of durum wheat, modern durum wheat cultivars, and common bread wheat are grown in the country. The leaf rust population in Ethiopia consisted of three different forms, that varied greatly for ability to attack leaf rust resistance genes in wheat. One form was highly virulent to durum wheat, but was not able to attack common bread wheat. A second form was also virulent to durum wheat, but could also attack a few of the common bread wheat cultivars. The third form was not able to attack durum wheat, but was highly virulent to common bread wheat cultivars that are grown throughout the world, including the U.S. The highly diverse population of P. triticina in Ethiopia is due to the unique mixture of durum wheat and common wheat cultivars that are grown. This information can be used by wheat breeders and plant pathologists to develop durum and common wheat cultivars with improved leaf rust resistance.

Technical Abstract: Collections of Puccinia triticina, the wheat leaf rust fungus, were obtained from tetraploid and hexaploid wheat in the central highlands of Ethiopia, and a smaller number from Kenya from 2011 to 2013, in order to determine the genetic diversity of this wheat pathogen in a center of host diversity. 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 genotypes with 10 simple sequence repeat (SSR) primers. Nine virulence phenotypes were described among the 193 isolates tested for virulence. Phenotype BBBQJ found only in Ethiopia, was predominantly collected from tetraploid wheat. Phenotype EEEEE also found only in Ethiopia, was exclusively collected from tetraploid wheat and was avirulent to the susceptible hexaploid wheat Thatcher. Phenotypes MBDSS and MCDSS found in both Ethiopia and Kenya, were predominantly collected from common wheat. Phenotypes CCMSS, CCPSS, and CBMSS were found in Ethiopia from common wheat at low frequency. Phenotypes TCBSS and TCBSQ were found on durum wheat and common wheat in Kenya. Four groups of distinct SSR genotypes were described among the 48 isolates genotyped. Isolates with phenotypes BBBQJ and EEEEE were in two distinct SSR groups, and isolates with phenotypes MBDSS and MCDSS were in a third group. Isolates with CCMSS, CCPSS, CBMSS, TCBSS, and TCBSQ phenotypes were in a fourth SSR genotype group. The diverse host environment of Ethiopia has selected and maintained a genetically divergent population of P. triticina.