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Document Type:Latin Dissertation
Language of Document:English
Record Number:53579
Doc. No:TL23533
Call number:‭3220018‬
Main Entry:Maria Eugenia Ordonez
Title & Author:Virulence, molecular diversity, and life cycle evolution of two rust fungi, in part as, Virulence and molecular characterization of a world-wide collection of Puccinia triticina from durum wheat, and, Evolutionary relationship between sympatric macrocycliMaria Eugenia Ordonez
College:University of Minnesota
Date:2006
Degree:Ph.D.
student score:2006
Page No:107-107 p.
Abstract:Collections of Puccinia triticina with virulence to durum wheat from Argentina, Chile, Ethiopia, France, Mexico, Spain, and the USA, and a group of representative races of P. triticina from bread wheat from the USA, were tested for virulence phenotypes on 35 Thatcher differential lines, and with eleven simple sequence repeat (SSR) markers. Similar virulence phenotypes among P. triticina from durum wheat were found that were distinct from the virulence phenotypes of the bread wheat P. triticina isolates. Isolates from durum wheat were avirulent to many Lr genes commonly found in bread wheat. Most isolates from Ethiopia were avirulent to Thatcher and all near-isogenic lines. The large majority of P. triticina isolates from durum wheat had less than 8% genetic dissimilarity for SSR genotypes, while isolates from Ethiopia had 55% dissimilarity with respect to the other durum leaf rust collections. Isolates from bread wheat had over 70% genetic dissimilarity from the durum wheat leaf rust population. Populations of P. triticina from South America, North America and Europe had very similar virulence phenotypes and were closely related for SSR genotypes which suggests a recent common ancestor, while populations from Ethiopia and bread wheat had distinct virulence phenotypes and SSR genotypes, which indicates different origins. No studies have confirmed that in rust fungi a change from a macrocyclic to a microcyclic life cycle is unidirectional, so that the rust can no longer regain a macrocyclic life form. I analyzed the rDNA ITS sequence of the macrocylic Tranzschelia pruni-spinosae var. americana and the microcyclic T. fusca infecting Anemone quinquefolia simultaneously, to test this hypothesis. Parsimony analysis separated the two rust species into three well-supported clades. In one third of the samples analyzed, collections of aecia and telia coexisting on an A. quinquefolia clone belonged to the same phylogenetic group, while for the remaining collections each spore type belonged to a different group. Results indicated that changes in life cycle are not necessarily permanent and therefore the rust could adopt either a macrocyclic or microcyclic life form. Spore stage of the life cycle was not predictive of the rust's phylogenetic classification.
Subject:Biological sciences; Virulence; Molecular diversity; Life cycle; Durum wheat; Sympatric; Puccinia triticina; Tranzschelia; Plant pathology; Agronomy; 0480:Plant pathology; 0285:Agronomy
Added Entry:J. A. Kolmer
Added Entry:University of Minnesota