Dr. Robert Brueggeman

“Rpt5, Rpg1, and rpg4/5: Characterizing Broad Resistance against Important Necrotrophic and Biotrophic Fungal Pathogens of Barley”
Dr. Robert Brueggeman Associate Professor, Barley Breeding/Molecular Genetics
Robert A. Nilan Endowed Chair in Barley Research and Education Dept. of Crop and Soil Sciences, WSU

Abstract
Two pathogens that threaten barley production worldwide are the necrotrophic fungal pathogen Pyrenophora teres f. teres (the causal agent of net form net blotch) and the biotrophic fungal pathogen Puccinia graminis f. sp. tritici (the cause agent of wheat stem rust). Net form net blotch resistance/susceptibility is complex, but the broadest and most effective resistance is provided by the Rpt5 gene which has been deployed in important barley producing regions worldwide. Rpt5 was effective against all known isolates of P. teres f. teres until the recent emergence of Moroccan and Canadian isolates with virulence on Rpt5. Stem rust resistance in North American barley has primarily relied on a single source of resistance, but rpg4/5 has recently been deployed to address North American isolates with virulence on Rpg1. Alarmingly, the recent characterization of stem rust populations from Washington determined that 99% of the isolates were virulent on Rpg1, 16% were virulent on rpg4/5, and 10% were virulent on both genes when stacked together. This was the first report of P. graminis f. sp. tritici races or isolates that were virulent on both R‐genes when stacked together, representing the most virulent Pgt population on barley from across the globe. In this talk I will present our research to identify and characterize these important barley resistance genes and the pathogen effectors that interact with them. An interesting point of discussion is how and why these virulent pathogen populations arose. It is understandable for Rpt5 virulence as the gene was deployed over large acreage under heavy disease pressure. However, for the PNW Rpg1‐rpg4/5 virulence it is a mystery as neither gene was deployed in PNW barley varieties.

For more information regarding Dr. Brueggeman’s seminar, please see the seminar announcement.