Link to home

Gene Action and Linkage of Avirulence Genes to DNA Markers in the Rust Fungus Puccinia graminis

August 2000 , Volume 90 , Number  8
Pages  819 - 826

P. J. Zambino , A. R. Kubelik , and L. J. Szabo

Cereal Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 1551 Lindig Ave., St. Paul, MN 55108

Go to article:
Accepted for publication 13 April 2000.

Two strains of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, were crossed on barberry, and a single F1 progeny strain was selfed. The parents, F1, and 81 F2 progeny were examined for virulence phenotypes on wheat differential cultivars carrying stem rust resistance (Sr) genes. For eight Sr differentials, phenotypic ratios are suggestive of single dominant avirulence genes AvrT6, AvrT8a, AvrT9a, AvrT10, AvrT21, AvrT28, AvrT30, and AvrTU. Avirulence on the Sr; (Sr ‘fleck’) differential showed phenotypic ratios of approximately 15:1, indicating epistatic interaction of two genes dominant for avirulence. Avirulence on Sr9d favored a 3:13 over a 1:3 ratio, possibly indicating two segregating genes-one dominant for avirulence and one dominant for avirulence inhibition. Linkage analysis of eight single dominant avirulence genes and 970 DNA markers identified DNA markers linked to each of these avirulence genes. The closest linkages between AvrT genes and DNA markers were between AvrT6 and the random amplified polymorphic DNA marker crl34-155 (6 centimorgans [cM]) AvrT8a and the amplified fragment length polymorphism marker eAC/mCT-197 (6 cM) and between AvrT9a and the amplified fragment length polymorphism marker eAC/mCT-184 (6 cM). AvrT10 and AvrTU are linked at distance of 9 cM.

Additional keywords: AFLP, avirulence gene nomenclature, molecular map, RAPD, Triticum aestivum, T. durum.

The American Phytopathological Society, 2000