Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/1995
Publication Date: N/A
Interpretive Summary: A new barley disease, barley stripe rust, has appeared in North America and has spread from Texas to the Pacific Northwest. The disease has caused losses of 30-70% in South America and Mexico, where it occurred prior to entering the United States. Similar losses are possible, since varieties in the United States are susceptible. Studies were conducted using virulence tests and a molecular technique called "random amplified polymorphic DNA (RAPD) assay to determine the relationship of the barley stripe rust pathogen to stripe rust of wheat, stripe rust of bluegrass, leaf rust of barley, leaf rust of wheat, and stem rust of wheat. The results show that barley stripe rust can attack wheat and wheat stripe rust can attack barley. However, most wheat varieties are resistant to barley stripe rust and most barley varieties are resistant to wheat stripe rust. The barley and wheat stripe rusts cannot attack bluegrass and bluegrass stripe rust cannot attack barley or wheat. The results also show that there are at least 14 races of barley stripe rust in the United States. Therefore, the barley stripe rust population is highly variable and selection for resistance depends upon what race is used. RAPD analyses clearly separated barley stripe rust from wheat stripe rust, bluerass stripe rust, barley leaf rust, wheat leaf rust, and wheat stem rust. Barley stripe rust and wheat stripe rust are more closely related to each other than they are to bluegrass stripe rust and the three forms of stripe rust are not closely related to the other rusts.
Technical Abstract: Relationships of Puccinia striiformis f. sp. hordei (stripe rust of barley) to P. striiformis f. sp. tritici (stripe rust of wheat), P. striiformis f. sp. poae (stripe rust of bluegrass), P. hordei (leaf rust of barley), P. recondita f. sp. tritici (leaf rust of wheat), and P. graminis f. sp. tritici (stem rust of wheat) in the United States were determined by virulence and random amplified polymorphic DNA )RAPS) analyses. All isolates of P. s. hordei were virulent on some cultivars of wheat (Triticum aestivum), and some isolates of P. s. tritici were virulent on some cultivars of barley (Hordeum vulgare). However, P. s. hordei was avirulent on most wheat cultivars and P. s. tritici was avirulent on most barley cultivars. P. s. hordei and P. s. tritici were not virulent on bluegrass (Poa pratensis) and P. s. poae was not virulent on either barley or wheat. Among 31 barley cultivars tested, eight were resistant to all isolates of P. s. hordei. Fourteen races of P. s. hordei were detected based on reactions of 11 barley cultivars that were selected to differentiate races of barley stripe rust. RAPD analyses clearly differentiated the isolates of P. s. hordei, P. s. tritici, and P. s. poae. Puccinia s. hordei and P. s. tritici were more closely related to each other than they were to P. s. poae. The three formae speciales of P. striiformis were not closely related to P. hordei, P. r. tritici, and P. g. tritici.