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United States Department of Agriculture

Agricultural Research Service

Title: Genetic Mapping of Avirulence Genes in the Wheat Stem Rust Fungus, Puccinia Graminis

Authors
item Szabo, Les
item Balmuth, Alexi

Submitted to: International Congress on Molecular Plant-Microbe Interactions
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 1998
Publication Date: N/A

Technical Abstract: Puccinia graminis f.sp. tritici and the disease it causes (black stem rust of wheat) have served as a paradigm for plant pathologists, primarily owing to the importance of the host and the severities of past epidemics. Genetic studies have demonstrated that race-specific resistance in this system fits the gene-for-gene theory. Currently, more than 60 different resistance/avirulence gene pairs have been defined for the interaction between wheat and P. graminis f.sp. tritici. A mapping population of 81 F2 progeny is currently being used to develop a genetic linkage map of P. graminis f.sp. tritici. The current genetic map consists of approximately 550 DNA markers (RAPD and AFLP) and eight avirulence genes (AvrT6, AvrT8a, AvrT9a, AvrT10, AvrT21, AvrT28, AvrT30 and AvrTU) in 55 linkage groups. These eight avirulence genes are contained on seven linkage groups. The closest DNA marker (CRL134-155) to an avirulence gene is approximately 5.5 centimorgans from AvrT6. Since this fungus is dikaryotic and has a high level of heterozygosity, a set of co-dominant markers needs to be developed in order to reduce the number of linkage groups. Currently, simple sequence repeats (SSRs) are being cloned from P. graminis to develop a set of SSLP markers.

Last Modified: 11/26/2014