Myrotoxins Produced by Myrothecium Roridum a Fungus Pathogenic to Tomatoes
Trichothecenes are a series of sesquiterpene compounds that have been isolated either as fungal met a bolites or from the Brazilian shrubs Baccharis megapotomica and Baccharis coridifolia. The first trichothecene isolated from fungi was trichothec in from Trichothecium roseum in 1948 (Tamm, 1977), and since then over 80 naturally occurring trichothecenes have been reported (McDougal and Schmuff, 1985). Our interest in trichothecenes started with the report of Kupchan in 1977 that B. megapotomica plants contained relatively high levels of “baccharinoids” which are structurally related to the fungally produced macrocyclic trichothecene roridins differing only by the presence of an extra oxygen in the A ring of baccharinoids (Kupchan et al. , 1977). The presence of trichothecenes or baccharinoids was unusual for two reasons; first, the trichothecenes are phyto toxic yet the Baccharis plants appeared to be normal and secondly, when plants were grown in Maryland from seeds collected in Brazil, the plants did not contain trichothecenes. When B. megapotomica seedling roots were exposed to an aqueous solution containing roridin A, we found that the compound was translocated to the upper part of the plant where it was metabolized to forms identical to the naturally occurring baccharinoids (Jarvis et al. , 1981). Other plant species exposed tororid in A were killed whereas B. megapotomica showed no evidence of phyto toxicity. Based on these studies, we suggested that the source of the trichothecene baccharinoids present in B. megapotomica was probably soil fungi located near the plant. As the fungus grew it released trichothecenes e. g. roridins which were absorbed, translocated and metabolized to baccharinoids in the leaf tissue.
KeywordsToxicity Filtration Agar Vinyl Diene
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- Bruton, B.R. (1982). Myrothecium roridum, a potentially devastating pathogen of muskmelons in south Texas. Phytopath. 72, 355.Google Scholar
- Kuti, J.O., Ng, T. J., and Bean, G.A. (1985). Evidence for a “ pathotoxin” role of trichothecene metabolites produced by as train of Myrothecium roridum pathogenic to muskmelon (Cucumis melo L. ) Phytopath. 75, 1358.Google Scholar
- Schieber, E., and Echandi, E. (1963). Myrothecium stem necrosis and leaf spot, a new disease of coffee in Guatemala. Phytopath. 53, 24–25.Google Scholar
- Stevenson, J.A., and McCollock, L.P. (1947). Myrothecium as a tomato rot organism. PI. Dis. Reptr. 31, 147–149.Google Scholar
- Tamm, C. (1977). Chemistry and biosynthesis of trichothecenes. In Mycotoxinsin human health, pp. 209–228 (J.V. Rodricks, C.W. Hesseltine and M.A. Mehlman, eds. ) Pathotox, Publ. Park Forest, I L.Google Scholar
- Ueno, Y. (1983). Trichotheienes: Chemical, Biological and Toxicological Aspects. Kodansha, Tokyo, Japan, pp. 313.Google Scholar