Classification Of Fungi By Alexopoulos Pdf Free

Throughout the years, mycologists have strived to classify fungi based on their reproductive and vegetative traits. Traditionally, fungi are divided into four classes: Ascomycetes, Phycomycetes, Basidiomycetes, and Deuteromycetes. Phycomycetes include fungi such as Oomycetes, Chytridiomycetes, and Zygomycetes, which are considered lower fungi with origins traced back to algae.

A comprehensive phylogenetic classification of the kingdom Fungi is proposed, with reference to recent molecular phylogenetic analyses, and with input from diverse members of the fungal taxonomic community. The classification includes 195 taxa, down to the level of order, of which 16 are described or validated here: Dikarya subkingdom nov.; Chytridiomycota, Neocallimastigomycota phyla nov.; Monoblepharidomycetes, Neocallimastigomycetes class. nov.; Eurotiomycetidae, Lecanoromycetidae, Mycocaliciomycetidae subclass. nov.; Acarosporales, Corticiales, Baeomycetales, Candelariales, Gloeophyllales, Melanosporales, Trechisporales, Umbilicariales ords. nov. The clade containing Ascomycota and Basidiomycota is classified as subkingdom Dikarya, reflecting the putative synapomorphy of dikaryotic hyphae. The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotina. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella.

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Alexopoulos had 40 students during his academic life, including Master's, doctoral and post-doctoral students.[2] Among these students was Meredith Blackwell, an emerita Professor at the Louisiana State University who focuses on fungi associated with arthropods,[10] and mycologist O'Neil Ray Collins.[11] On the upper branches of Alexopoulos' "scientific genealogic tree" lies the Heinrich Anton De Bary[1] known as the Father of Plant Pathology.[12]

C. J. Alexopoulos (1962) also included slime molds under fungi andplaced them as Division Mycota and it was divided into two subdivisions:Myxomycotina (wall-less form) and Eumycotina (true, walled fungi).

Ainsworth G. C. (1966, 71, 73) proposed a more natural system ofclassification of fungi. This classification is based on morphology, especiallyof reproductive structure. He includes fungi along with slime molds underthe kingdom Mycota.

Myxomycota i., slime molds and Eumycota or true fungi. Divisionsare subsequently divided into subdivision, class, subclass, order, family andthen to genus. According to his classification, division ends in mycota,subdivision in mycotina, class in mycetes, subclass in mycetidae order inales and family in aceae.

Later, much more handy system of classification was proposed by Gwynne-Vaughan and Barnes (1926). In their classification, Myxomycetes were not considered as fungi and were included by them as forms resembling fungi.

E. A. Gaumann and B. O. Dodge (1928) also did not consider the Myxomycetes as fungi. They classified fungi based on both the phases (i.e., haploid and diploid) of life cycle; structure of thallus and organs of fructifications.

C. J. Alexopoulos (1962) also included slime molds under fungi and placed them as Division Mycota and it was divided into two subdivisions: Myxomycotina (wall-less form) and Eumycotina (true, walled fungi).

Later, C. J. Alexopoulos and C. W. Mims (1979) placed fungi and slime molds under the kingdom of their own, called Myceteae under the superkingdom Eukaryonta. The kingdom is divided into three divisions and further the divisions are divided into sub-division, class and form-class.

Ainsworth G. C. (1966, 71, 73) proposed a more natural system of classification of fungi. This classification is based on morphology, especially of reproductive structure. He includes fungi along with slime molds under the kingdom Mycota.

Myxomycota i.e., slime molds and Eumycota or true fungi. Divisions are subsequently divided into subdivision, class, subclass, order, family and then to genus. According to his classification, division ends in mycota, subdivision in mycotina, class in mycetes, subclass in mycetidae order in ales and family in aceae.

Say for example, the Mastigo- mycotina is a composite grouping covering all fungi that form motile flagellated zoospores. Among others, unrelated classes like Chitridio- mycetes and Oomycetes were included in the same group. Oomycetes has indeed quite a different evolutionary origin to that of most other fungi.

Though members of fungi show similarity in their morphology, mode of nutrition and ecology, but the higher dissimilarity is observed in the base sequences of their 18s rRNA (or more precisely in the DNA coding for it), which is now considered as the most important parameter to determine the genetic relationship. Thus, it shows that the fungi are polyphyletic aggregation of unrelated members.

Based on comparison of several factors such as, 18s rRNA, cytoskele- ton protein, chemical features like chitin, mitochondrial codon UGA coding for tryptophan instead of termination, storage of glycogen, elongation factors and morphological structure of motile cells like male gamete in animal and zoospores in fungi, there is close similarity of fungi with animals than to other two groups like Straminopila and Protozoa.

The earlier consideration of the sub-division Deuteromycotina representing the asexual stages of Ascomycotina and Basidiomycotina (Ainsworth 1973, Hawksworth et al1983) was now reconsidered as a formal taxon as they are not a monophyletic group. The members are described under Mitosporic fungi.

The organisms of the fungal lineage include mushrooms, rusts,smuts, puffballs, truffles, morels, molds, and yeasts, as well asmany less well-known organisms (Alexopoulos et al., 1996). About70,000 species of fungi have been described; however, some estimatesof total numbers suggest that 1.5 million species may exist(Hawksworth, 1991; Hawksworth et al., 1995).

As the sister group of animals and part of the eukaryotic crowngroup that radiated about a billion years ago, the fungi constitutean independent group equal in rank to that of plants and animals.They share with animals the ability to export hydrolytic enzymes thatbreak down biopolymers, which can be absorbed for nutrition. Ratherthan requiring a stomach to accomplish digestion, fungi live in theirown food supply and simply grow into new food as the localenvironment becomes nutrient depleted.

Figure 1: Hyphae of a wood-decaying fungus found growing on theunderside of a fallen log. The metabolically active hyphae havesecreted droplets on their surfaces. Copyright M. Blackwell1996.Prior to mating in sexualreproduction, individual fungi communicate with other individualschemically via pheromones. In every phylum at least one pheromone hasbeen characterized, and they range from sesquiterpines andderivatives of the carotenoid pathway in chytridiomycetes andzygomycetes to oligopeptides in ascomycetes and basidiomycetes.

Within their varied natural habitats fungi usually are the primarydecomposer organisms present. Many species are free-living saprobes(users of carbon fixed by other organisms) in woody substrates,soils, leaf litter, dead animals, and animal exudates. The largecavities eaten out of living trees by wood-decaying fungi providenest holes for a variety of animals, and extinction of the ivorybilled woodpecker was due in large part to loss, through humanactivity, of nesting trees in bottom land hardwoods. In some lownitrogen environments several independent groups of fungi haveadaptations such as nooses and sticky knobs with which to trap anddegrade nematodes and other small animals. A number of references onfungal ecology are available (Carroll and Wicklow, 1992; Cooke andWhipps, 1993; Dix and Webster, 1995).

However, many other fungi are biotrophs, and in this role a numberof successful groups form symbiotic associations with plants(including algae), animals (especially arthropods), and prokaryotes.Examples are lichens, mycorrhizae, and leaf and stem endophytes.Although lichens may seem infrequent in polluted cities, they canform the dominant vegetation in nordic environments, and there is abetter than 80% chance that any plant you find is mycorrhizal. Leafand stem endophytes are a more recent discovery, and some of thesefungi can protect the plants they inhabit from herbivory and eveninfluence flowering and other aspects of plant reproductive biology.Fungi are our most important plant pathogens, and include rusts,smuts, and many ascomycetes such as the agents of Dutch elm diseaseand chestnut blight. Among the other well known associations arefungal parasites of animals.

Fungal spores may be actively or passively released for dispersalby several effective methods. The air we breathe is filled withspores of species that are air dispersed. These usually are speciesthat produce large numbers of spores, and examples include manyspecies pathogenic on agricultural crops and trees. Other species areadapted for dispersal within or on the surfaces of animals(particularly arthropods). Some fungi are rain splash or flowingwater dispersed. In a few cases the forcible release of spores issufficient to serve as the dispersal method as well. The function ofsome spores is not primarily for dispersal, but to allow theorganisms to survive as resistant cells during periods when theconditions of the environment are not conducive to growth. be457b7860