Rust fungus

Rost-dl, n. slushing oil. -pilz, m. (Bot.) rust fungus, rijst. 

In additional tests, the suppressor activities of pectins in the intact host/pathogen-interaction were investigated by injecting genetically resistant plants with pectic substances prior to inoculation with the rust fungus. Infected leaves were harvested, cleared, and stained with Calcofluor one week after inoculation, and fungal growth was assessed under the UV-epifluorescence microscope. 

Solutions of different pectic substances were injected into healthy wheat plants, with or without the glycoproteogalactan elicitor, and the activities of the enzymes PAL and POD were determined. These enzymes are involved in the hypersensitive reaction of wheat against the rust fungus, and increased activities can be expected after elicitation, whereas suppressor active substances will cause a reduction of the elicitor-induced enzyme activities. 

Macek, K.J., M.A. Lindberg, S. Sauter, K.S. Buxton, and P.A. Costa. 1976. Toxicity of Four Pesticides to Water Fleas and Fathead Minnows. U.S. Environ. Protection Agen. Rep EPA-600/3-76-099. 57 pp. Macko, V., J.A.A. Renwick, and J.F. Rissler. 1978. Acrolein induces differentiation of infection structures in the wheat stem rust fungus. Science 199 442-443. 

Highly resistant wheat varieties exhibit a typical hypersensitive response when infected with an avirulent race of the stem rust fungus. Host cells which are penetrated by a fungal haustorium undergo rapid necrotization, thus depriving the biotrophic parasite of its nutritional basis. 

We will now consider the evidence that has accumulated to show the participation of lignification in the hypersensitive resistance of wheat to the wheat stem rust fungus, Puccinia graminis f. sp. tritici. 

When highly resistant wheat varieties are inoculated with an avirulent race of the stem rust fungus, fungal growth is arrested by the hypersensitive death of the first penetrated host cells (30,31.) Even in very densely inoculated leaves, the reaction of less than one percent of the host cells is sufficient to stop further development of the parasite. This small percentage may be the reason, why no increased content of biochemically determined lignin was measured in infected hypersensitive wheat leaves (60,61). 

However, when an elicitor (see below), isolated from the stem rust fungus (62), is injected into the intercellular spaces of wheat leaves almost every cell in the infiltrated area exhibits a hypersensitive-like reaction (62-65). In the elicitor treated leaves, lignin content as determined by the thioglycolic acid procedure clearly increased (66). 

Hatcher, P. E., Paul, N. D., Ayres, P. G. and Whittaker, J. B. (1994a). The effect of an insect herbivore and a rust fungus individually, and combined in sequence, on the growth of 2 Rumex species. New Phytologist 128 71-78. 

Connick, W. J. and French, R. C. (1991). Volatiles emitted during the sexual stage of the Canada thistle rust fungus and by thistle flowers. Journal of Agricultural and Food Chemistry 39 185-188. 

Wheat is a curious case. Resistance to the rust disease periodically breaks down in wheat. As soon as the search discovers a new gene for resistance in wheat, a new race of the rust fungus appears. This is the classic case of the gene-for-... 

Puccinia chondrillina Bubak. Syd., a rust fungus from Europe, determined to be a virulent, host-specific, and safe biocontrol agent, was introduced into Australia in 1971 to control Chondrilla iuncea L., rush skeletonweed (27. 28). In 1976 it was introduced into California and later into other western states in the U.S. (29-31). The biology of this pathogen, weed control success, and assessment of the economic impact of controlling rush skeletonweed in Australia have been reviewed (23, 27-31). In summary, the... 

Puccinia carduorum Jacky, a rust fungus from Turkey, was released in 1987 on a limited basis in Virginia to control musk thistle, Carduus thoermeri Weinm. (=C. nutans L. ssp. leiophyllus [Petrovic] Stoj. Stef.), a problem in about 15% of all counties in the United States and in Canada. Detailed studies in quarantine... 

Phatak et al. (25) have demonstrated that a native rust fungus, Puccinia canaliculata (Schw.) Lagh., can be used in an augmentation... 

Pests and diseases are seldom a problem on cultivated barberries. Many states prohibit growing common barberry Berberis vulgaris), which is an alternate host to a rust fungus that also attacks cereal grains. Check with your extension agent for local restrictions. 

If you place a Colorado potato beetle on a potato leaf, and the beetle doesn t eat anything, you don t have a pest problem. Similarly, if you put rust fungus particles on a snapdragon leaf, and they don t infect the leaf, you don t have a disease problem. Disease only occurs when the proper environmental conditions exist to allow the pathogen to penetrate and grow into the host plant. You can picture this interrelationship between organism, environment, and plant as a triangle, like the one shown below. 

Derivation Isolated from rust fungus in 1952, synthesized in 1969. 

Preinfection Changes In Germlings of a Rust Fungus Induced by Host Contact... 

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