Title: Virulent races of Puccinia striiformis identified in the United States in 2007 Authors
Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2008
Publication Date: June 1, 2008
Citation: Chen, X., Wan, A., Richardson, K.L. 2008. Virulent races of Puccinia striiformis identified in the United States in 2007. APS Annual Meeting. Phyto 98:S36. Technical Abstract: Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (PST), and stripe rust of barley, caused by P. striiformis f. sp. hordei (PSH), were monitored by collaborators throughout the US. In 2007, stripe rust of wheat occurred in more than 16 states while stripe rust of barley was found in California, Colorado, and Washington. Both stripe rusts were generally in low levels except epidemic occurred in some areas. Urediniospores from infected leaf samples were increased on susceptible seedlings of either ‘Nugaines’ wheat or ‘Steptoe’ barley. Isolates of PST were tested on a set of 20 wheat differential genotypes and PSH isolates were tested on a set of 12 barley differential genotypes for identifying virulent races. Five PSH races and 30 PST races were detected. The most frequent races were PST-114 (virulent on Lemhi, Heines VII, Moro, Produra, Yamhill, Stephens, Lee, Fielder, Tres, Express, Yr8, Yr9, Clement, and Compair), PST-116 (all PST-114 virulences plus Paha), and PST-115 (all PST-116 virulence except for Moro). Among the 30 PST races, 11 were first identified in 2007. New race PST-127, which is the most virulent race identified to date, virulent on all 20 wheat differential genotypes except for Moro (Yr10, YrMor), Yr5, and Tres (YrTr1, YrTr2). This race has the combination of virulence on Yr1, Yr2, Yr3a, Yr4a, Yr6, Yr7, Yr8, Yr9, Yr17, Yr19, Yr20, Yr21, Yr22, Yr23, YrExp1, YrExp2, and several other resistance genes.