4 Chapter I 1.3 Classification of Fungi In the general taxonomic classification,fungi are grouped in terms of the fol- lowing ranks:division,class,order,family,tribe,genus,section,and species.In the binomial description of a fungus,the first name is that of the genus and the second name is the species.The name (not italicized)that follows this may be that of who first described the species Thereare ofte varietiesand strains The a r in a cu portant in defi ing the organismu te a particular m aboiteC some metabolites may be specific to particular strains,others may be more common and are found in a section of a genus.The structure of the reproductive organs and the mechanisms of reproduction form the basis of the classification of fungi.These organisms may be broadly grouped in the following way.There are the Phycomycetes or lower fungi.which have a simple thallus bearing the spores They possess s unicellular aseptate hyphae.In some classifications this class name is treated as a trivial name for the Mastigon otina and Zygomycotina.Ty ex ples are hich ine clud ra species and th 019 es,which Rhizopus and Phycomyces species.The 'damping-off'fungus Pythium ultimum. found growing across over-zealously watered germinating seeds,is an example A second group are the higher fungi which have septate hyphae,and these can be divided into the Ascomycetes and the Basidiomycetes.In the Ascomycetes the spores are borne in a sac-like structure known as an ascus.This type of fruiting body or ascocarp is found in Mon species.The fung pr the colour red ric an thes The Aspergillus be to the e cla Know Plectomycetes.The spores are held in a pea haped perithecium in another clas known as the Pyrenomycetes.The saprophytic plant parasites of the Hypocreales are also members of this group.Some of the best known of the higher fungi are Basidiomycetes.Here the spores are borne in special distinctive fruiting bodies. The edible part of the common mushroom,Agaricus bisporus,is a typical example The final large group are the Fungi Imperfecti or Deuteromy etes In th organis ns the erfect o of r oduction is rare most pa ture egeta e The Fusaria are know n can be conl use some ungi originally cla sified within the Fungi Imperfecti do have both an asexual a perfect stage.Thus the fungus that produces the gibberellin plant hormones. Gibberella fujikuroi,is the perfect stage of Fusarium monoliforme. The naming of fungi has undergone many changes over the years and this can be a source of confusion.For example,Ophiobolus graminis was the name given to a serious pathogen of wheat.This name was incorporated into tha to a family etabolites,the which were Howeve the fungus s no wn as Ga myces graminis.Oph lanes are also produced by a rice pathogen th was a one time known as Helminthosporium oryzae or Drechslera oryzae and is now described as Bipolaris oryzae.Many of the Polyporus species,which gave their1.3 Classification of Fungi In the general taxonomic classification, fungi are grouped in terms of the fol￾lowing ranks: division, class, order, family, tribe, genus, section, and species. In the binomial description of a fungus, the first name is that of the genus and the second name is the species. The name (not italicized) that follows this may be that of the author who first described the species. There are often varieties and strains of particular species. The accession number in a culture collection can be im￾portant in defining the organism used to isolate a particular metabolite. Although some metabolites may be specific to particular strains, others may be more common and are found in a section of a genus. The structure of the reproductive organs and the mechanisms of reproduction form the basis of the classification of fungi. These organisms may be broadly grouped in the following way. There are the Phycomycetes or lower fungi, which have a simple thallus bearing the spores. They possess unicellular aseptate hyphae. In some classifications this class name is treated as a trivial name for the Mastigomycotina and Zygomycotina. Typical examples are the Peronosporales, which include plant pathogens such as Pythium and Phytophthora species and the Mucorales, which include the common Mucor, Rhizopus and Phycomyces species. The ‘damping-off ’ fungus Pythium ultimum, found growing across over-zealously watered germinating seeds, is an example. A second group are the higher fungi which have septate hyphae, and these can be divided into the Ascomycetes and the Basidiomycetes. In the Ascomycetes the spores are borne in a sac-like structure known as an ascus. This type of fruiting body or ascocarp is found in Monascus species. The fungus M. ruber, which produces the red colour on Chinese red rice, is an example of these. The genera Penicillium and Aspergillus belong to the class of Ascomycetes known as the Plectomycetes. The spores are held in a pear-shaped perithecium in another class known as the Pyrenomycetes. The saprophytic plant parasites of the Hypocreales are also members of this group. Some of the best known of the higher fungi are Basidiomycetes. Here the spores are borne in special distinctive fruiting bodies. The edible part of the common mushroom, Agaricus bisporus, is a typical example. The final large group are the Fungi Imperfecti or Deuteromycetes. In these organisms, the perfect stage of reproduction is rare or unknown and for the most part they are cultured vegetatively. The Fusaria are the best known of these. This classification can be confusing because some fungi originally clas￾sified within the Fungi Imperfecti do have both an asexual imperfect stage and a perfect stage. Thus the fungus that produces the gibberellin plant hormones, Gibberella fujikuroi, is the perfect stage of Fusarium monoliforme. The naming of fungi has undergone many changes over the years and this can be a source of confusion. For example, Ophiobolus graminis was the name given to a serious pathogen of wheat. This name was incorporated into that given to a family of terpenoid metabolites, the ophiobolanes, which were isolated from the fungus. However, the fungus is now known as Gaeumanno￾myces graminis. Ophiobolanes are also produced by a rice pathogen that was at one time known as Helminthosporium oryzae or Drechslera oryzae and is now described as Bipolaris oryzae. Many of the Polyporus species, which gave their 4 Chapter 1