Myrothecium spp

Some trichothecenes, a group of mycotoxins, have macrodiolide or macrotri-olide skeletons. Trichothecenes inhibited protein synthesis by binding to the ribosomal peptidyltransferase site [141]. Roritoxins (roritoxin A, 113) are 16-membered ring macrodiolides isolated from Myrothecium roridum [142]. Verru-carin A (114) is an 18-membered ring macrotriolide produced by Myrothecium spp. [143]. 

The early work on the biosynthesis of the trichothecene nucleus related to the formation of trichothecolone (101) in Trichothecium roseum and of derivatives of verrucarol (102) in Myrothecium spp. This work has been reviewed in detail (248). The more recent work has been... 

The sequence of the hydroxylation and esterification steps in Myrothecium spp. fermentations between trichodermol (110) and the C-7 diastereoisomeric trichoverrins (C-6"S) (140) and isotrichoverrins (C-6"R) is unclear and has still to be tested with specifically labelled compounds. The pattern of secondary metabolites which could be intermediates, verrucarol (138), verrol (139), the trichodermadienediols (136) and the trichoverrols (137), again suggests a metabolic grid rather than a unique pathway. 

Like other micronutrients. Mo has been found to influence the incidence of plant diseases. Molybdenum application has been reported to decrease leaf-spot infection caused by Septoria sojina in soybeans (Girenko, 1975) and to decrease Verticillium wilt in tomatoes (Dutta and Bremner, 1981) and cotton (Gossypium spp.) (Miller and Becker, 1983). It also reduces the production of roridin E toxin by Myrothecium roridum (Fernando, Jarvis, and Bean, 1986) and zoosporangia formation by Phytophthora spp. (Halsall, 1977). Haque and Mukhopadhyay (1983) observed that soil application of Mo caused some reduction in the population of parasitic nematodes. Whether these effects are due to some specific role of Mo in plant disease resistance or are indirect effects of Mo through plant metabolism is not certain. 

The simple trichothecenes are products of Acremonium, Fusarium, Myrothecium, Stachybotrys and Trichoderma spp., and one species each of Cephalosporium, Cylindrocladium, Dendrostilbella, Gliocladium, Memnoniella, Microdocium, Spicellum and Trichothecium. Trichothecium roseum is, nevertheless, responsible for 12 metabolic products with... 

The trichoverroids and fungal macrocycles are products of Myrothecium and Stachybotrys spp., and one species each of Acremonium, Ceratopycnidium, Cercophora, Cylindrocarpon, Phoma, Phomopsis, and Verticinimonosporium. Acremonium, Ceratopycnidium, Cercophora and Phoma are new sources reported since 1991. 

Trichodiene (49), the last hydrocarbon intermediate in the pathway, has been isolated from T. roseum, from Fusarium spp., and also from S. atra (Table 8). Specific labelling experiments have shown it to be a precursor of trichodiol (55) and 12,13-epoxy trichothecene (73), in addition to trichothecolone (101), in T. roseum (277) it is also a precursor of isotrichodiol (53) (219) and 3-acetylvomitoxin (104) in F. culmorum (278). However, relatively little work has been done on this stage of the pathway to simple trichothecenes in Myrothecium, Stachybotrys and Trichoderma spp. 

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