Submitted to: Molecular Plant Pathology
Publication Type: Review Article
Publication Acceptance Date: 1/15/2005
Publication Date: 3/1/2005
Citation: Leonard, K.L., Szabo, L.J. 2005. Pathogen profile: Stem rust of small grains and grasses caused by Puccinia graminis. Molecular Plant Pathology. 6:99-111.
Technical Abstract: Stem rust has been a serious disease of wheat, barley, oat, and rye, as well as various important grasses including timothy, tall fescue, and perennial ryegrass. The stem rust fungus, Puccinia graminis, is functionally an obligate biotroph. P. graminis is a typical heteroecious rust fungus with the full complement of five distinct spore stages that occur during asexual reproduction on its gramineous hosts and sexual reproduction that begins in the resting spore stage and culminates on the alternate host, barberry (Berberis spp.). Various subdivisions of P. graminis into subspecies, varieties, and formae speciales have been proposed based on spore size and host range. Crossing studies and DNA sequence comparisons support the separation of at least two subspecies, but not the proposed separation based on spore size. The host range of P. graminis is very broad compared to that of most Puccinia spp.; it includes at least 365 species of cereals and grasses in 54 genera. Wheat stem rust, P. graminis f. sp. tritici was shown to infect 74 species in 34 genera in artificial inoculations of seedlings, but only 28 of those species belonging to eight genera were known to be natural hosts of the fungus. Infections in cereals or grasses occur mainly on stems and leaf sheaths, but occasionally they may be found on leaf blades and glumes as well.