Heterogeneity of the genus Myrothecium as revealed by cell wall polysaccharides
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O R I G I N A L PA P E R
Oussama Ahrazem · Begoña Gómez-Miranda · Alicia Prieto · Manuel Bernabé · J. Antonio Leal
Heterogeneity of the genus Myrothecium as revealed by cell wall polysaccharides
Received: 28 July 1999 / Revised: 24 January 2000 / Accepted: 24 January 2000 / Published online: 24 February 2000 © Springer-Verlag 2000
Abstract The polysaccharides obtained from the alkaliextractable, water-soluble fraction (F1SS) from the cell wall of Myrothecium verrucaria and Myrothecium atroviride were shown to be composed of β-(1→6)-galactofuranose fully substituted at O-2 by terminal residues of αglucopyranose and α-glucuronic acid. Glucuronic acid was substituted at O-4 by glucopyranose in the Myrothecium species M. inundatum, M. setiramosum, M. prestonii, M. tongaense and M. roridum. The acidic polysaccharides from Phaeostilbella atra (=Myrothecium atrum) and Myrothecium gramineum lacked the backbone of 2,6 di-O-substituted galactofuranose and contained a high amount of O-5-substituted β-galactofuranose. The structures of the polysaccharides isolated from Myrothecium cinctum and Myrothecium penicilloides were unrelated to each other and to the polysaccharides from the other species analysed. The usefulness of these polysaccharides as a characteristic for delimitation of the genus Myrothecium is discussed. Key words Myrothecium · Cell-wall polysaccharides · Taxonomy
Introduction The genus Myrothecium was first named in 1790 by Tode, who described it as a cup-shaped fungus with spores that become slowly viscous. At first only three species were described: M. inundatum, M. roridum and M. verrucaria.
O. Ahrazem · B. Gómez-Miranda · A. Prieto · J.A. Leal (✉) Centro de Investigaciones Biológicas, CSIC C/ Velázquez 144, 28006 Madrid, Spain e-mail: [email protected], Tel.: +34-91-5611800 ext. 4437, Fax: +34-91-5627518 M. Bernabé Instituto de Química Orgánica, Departamento de Química Orgánica Biológica, CSIC C/ Juan de la Cierva 3, 28006 Madrid, Spain
In 1972, Tulloch revised the genus and described eight known species, two new species and three new combinations. All Myrothecium species produce sporodochia with differentiated marginal hyphae and phialidic spores. Nevertheless, they show variation in the appearance of the fructifications since sporodochia display different degrees of complexity. It has been reported that the perfect state of Myrothecium species belongs to Nectria (Tulloch 1972). Most species are saprophytes and only M. roridum can be considered a serious plant pathogen, as it often causes leaf spot disease (Tulloch 1972). Myrothecium species have the ability to decompose cellulose. Because of their strong cellulolytic activity, isolates of M. verrucaria are used as standard test organisms in the degradation of textiles by moulds (Nicot and Olivry 1961). Numerous antibiotics have been isolated from M. roridum and M. verrucaria such as roridins, myrothecins and verrucarians (Mortimer et al. 1971). Since 1790 there have been 55 specific epithets used within the genus Myrothecium (Tulloch 1972), which sho
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