Classification Of Fungi Alexopoulos And Mims 1979 79.pdf
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Maullinia ectocarpii I. Maier, E. R. Parodi, R. Westermeier et D. G. Müller, is a parasite of Ectocarpus siliculosus and other phaeophycean algae, and it is characterized by features specific for the plasmodiophorids and has been described as a new genus and species by Maier et al. (2000). Plamodiophorids are obligate parasites of angiosperms (Kanyuka et al., 2003) and seaweeds (Schnepf, 1994). Considerations on the entire 18S rDNA of two genera of the group, Spongospora and Plasmodiophora, showed that they are not closely related to a range of protists and true fungi (Down et al., 2002). Many of them are involved in important diseases of brassicas, potato, cereal species and grass (Barr, 1979), and some of them are considered viral vectors, as for the rhizomania disease virus in sugar beet, and barley mild mosaic virus in cereals (Teakle, 1980; 1983). Plasmodiophorid life cycles normally involve the production of two types of intracellular plasmodia: namely, sporogenic and sporangial. Resting spores and zoosporangia respectively produce two types of biflagellate zoospores, the primary and the secondary ones (Dylewski, 1990; Kanyuka et al., 2003).In the original publication of M. ectocarpii (Maier et al., 2000) only one type of zoospores was described from thalli growing on both field and culture material of Ectocarpus siliculosus and other brown algae. In the present paper we describe a second type of zoospores produced by M.ectocarpii, hosted by E.siliculosus. The present paper deals with the ultrastructure of these zoospores, with emphasis in the configuration of the flagellar apparatus. These apparatuses are a stable attribute of mature fungal flagellate cells, and may serve to characterize cell types as wells as to taxonomically identify the organisms (Lange and Olson, 1976; Hardham, 1987; Dick, 1997). Its potential has been clearly perceptible also in high level fungal taxonomy (Dylewski, 1990; Cavalier-Smith, 2002; Prillinger et al., 2002), although it may be relevant at the generic level too (Barr and Allan, 1982). Although the genus Maullinia clearly seems to have affinities with all plasmodiophorid genera, its precise taxonomical affinities within this group are not clear in the present state of knowledge. Motile cells features have prove to be the most important criterion to infer phylogenetic relationships among the plasmodiophorids (Talley et al., 1978; Clay and Walsh, 1997), even though the origin of the simple cruciate root pattern in plasmodiophorids is not obvious owing to the absence of detailed root structures (Cavalier-Smith, 2002). 2b1af7f3a8