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Elias Perez
Elias Perez

Classification Of Fungi Alexopoulos And Mims 1979 Pdf 79 _VERIFIED_

A fungus (PL: fungi[2] or funguses[3]) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom,[4] separately from the other eukaryotic kingdoms, which by one traditional classification include Plantae, Animalia, Protozoa, and Chromista.

classification of fungi alexopoulos and mims 1979 pdf 79

The fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, and morphologies ranging from unicellular aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of the fungus kingdom, which has been estimated at 2.2 million to 3.8 million species.[5] Of these, only about 148,000 have been described,[6] with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans.[7] Ever since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christiaan Hendrik Persoon, and Elias Magnus Fries, fungi have been classified according to their morphology (e.g., characteristics such as spore color or microscopic features) or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits. Phylogenetic studies published in the first decade of the 21st century have helped reshape the classification within the fungi kingdom, which is divided into one subkingdom, seven phyla, and ten subphyla.

Before the introduction of molecular methods for phylogenetic analysis, taxonomists considered fungi to be members of the plant kingdom because of similarities in lifestyle: both fungi and plants are mainly immobile, and have similarities in general morphology and growth habitat. Although inaccurate, the common misconception that fungi are plants persists among the general public due to their historical classification, as well as several similarities.[18][19] Like plants, fungi often grow in soil and, in the case of mushrooms, form conspicuous fruit bodies, which sometimes resemble plants such as mosses. The fungi are now considered a separate kingdom, distinct from both plants and animals, from which they appear to have diverged around one billion years ago (around the start of the Neoproterozoic Era).[20][21] Some morphological, biochemical, and genetic features are shared with other organisms, while others are unique to the fungi, clearly separating them from the other kingdoms:

Although commonly included in botany curricula and textbooks, fungi are more closely related to animals than to plants and are placed with the animals in the monophyletic group of opisthokonts.[145] Analyses using molecular phylogenetics support a monophyletic origin of fungi.[51][146] The taxonomy of fungi is in a state of constant flux, especially due to research based on DNA comparisons. These current phylogenetic analyses often overturn classifications based on older and sometimes less discriminative methods based on morphological features and biological species concepts obtained from experimental matings.[147]

The Eccrinales and Amoebidiales are opisthokont protists, previously thought to be zygomycete fungi. Other groups now in Opisthokonta (e.g., Corallochytrium, Ichthyosporea) were also at given time classified as fungi. The genus Blastocystis, now in Stramenopiles, was originally classified as a yeast. Ellobiopsis, now in Alveolata, was considered a chytrid. The bacteria were also included in fungi in some classifications, as the group Schizomycetes.

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).


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