植物真菌学-lecture 1

植物真菌学Mycology,Lecture 1 Overview of the Fungi,Mycology is the scientific study of fungi mykes (Gr.) - cap; mushroom fungus (L.) = sphongos (Gr.) - sponge Mycology is improperly coined; according to the rules of Greek grammar it should be mycetology There are approximately 100,000 described species of fungi, however, it is estimated that there are over 1 million species of fungi on the planet.,What is a fungus?,What is a fungus?,A eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption, and reproduces by spores. The primary carbohydrate storage product of fungi is glycogen (糖原).Most fungi have a thallus composed of hyphae (sing. hypha) that elongate by tip growth,Fungal hyphae form a network called a mycelium (pl. mycelia),真菌不是植物真菌不含叶绿素，无根、茎、叶的分化。,Why study fungi?,Fungi are among the most diverse organisms on Earth, and are considered only second to the Insects in species diversity.,Fungi are ancient,Major fungal lineages are ancient, perhaps emerging one billion years agoFungi were present before the emergence of animals and vascular plants,Fungi and humans,Humans have utilized/interacted with fungi for thousands of years,Associations,Fungi are involved in symbiotic(共生的) relationships with a number of organisms Lichens (地衣）Mycorrhizas （菌根）Endophytes （植物内生菌）Mutualists （依生生物）,Decomposers,As saprotrophs, particularly as decomposers（分解者）, fungi are essential components of the carbon cycle and are among the few organisms that can break down lignin（木质素）,Pathogens,Fungi are important as pathogens of animals and plants. Over 70% of all plant diseases are caused by fungi（Irish potato famine caused by the fungus Phytophthora infestans） Skin，respiratory system disease 癣、灰指甲,Economics & Industry,Food industryBrewing and baking, commercial cultivation, cheese, tempeh(印尼豆豉), food spoilage, mycotoxinsIndustrialOrganic acids: citric acid for soft drinksMedicineAntibiotics: Penicillin, griseofulvin（灰黄霉素）, cyclosporin（环孢子菌素）, etc. vitamins、Chinese medicineEnzymesPectic enzymes, hemicellulase, etc.,Neurospora crassa: discovered by Shearer other biochemical pathways discovery of antibiotics theory of symbiosis Yeast: Molecular biology, Biotechnology,Major advances in science,Classification,Whittaker (1969) proposed 5 kingdoms: Prokaryotes (Monera原核生物界） Animals Plants Fungi Protista（原生生物界）,8 kingdoms（Cavalier-Smith 1991）are now recognized: Eubacteria（真细菌界） Archaebacteria（古细菌界）Archezoa （原始动物界或古真核生物界 ） Animalia, Plantae, Fungi （Eumycota） Chromista（假菌界）or (Stramenopila茸鞭生物界) Protozoa (原生动物界Protista, Protoctista),Fungi versus fungi,The small case “fungus” is used inclusively for a heterogenous group of organisms that have traditionally been studied by mycologists. “Fungi” refers to the organisms in the Kingdom Fungi, the true fungi, also called the “Eumycota”,Characters that separate the Fungi (=the Kingdom Fungi) from fungi,Table. Comparison of the characteristics of Fungi and Fungus-like Organisms,Kingdom Fungi Phyla: Chytridiomycota（壶菌门）Zygomycota（接合菌门）Ascomycota （子囊菌门） (inc. Deuteromycetes半知菌类)Basidiomycota（担子菌门）,Kingdom Stramenopila (Chromista)Phyla:Oomycota（卵菌门）Hyphochytriomycota（丝壶菌门）Labyrinthulomycota（网黏菌门） Kingdom ProtozoaPhyla:Plasmodiophoromycota（根肿菌门）Dictyosteliomycota（网柄菌门）Acrasiomycota（集胞菌门）Myxomycota（黏菌门）,How many species of fungi exist?,Number described = 80,000 (+1,700 new species each year),Estimating the number of fungal species,Hawksworth, D. L. (1991). The fungal dimension of biodiversity: magnitude, significance, and conservation. Mycological Research 95: 641-655Hawksworth, D.L. (2001) The magnitude of fungal diversity: the 1.5 million species estimate revisited. Mycological Research 105 (12): 1422-1432.,Flowering plants on British Isles described = 2,000 speciesFungi on British Isles described = 12,000 speciesRatio of 6 fungi to each plant speciesTotal number of described plant species = 250,000 (most plant species are believed to be described)6 x 250,000=1.5 million species of fungi!Less than 5% of which are described, and at the current rate of description, it will take 800 years to describe all extant species.,Classification is the systematic arrangement of organisms into groups based on established criteria. Systematics is the study of the relationships and classification of the living world in a system or conceptual hierarchy（等级）. Taxonomy, nomenclature are subcategories of systematics.Taxonomy is the study of the theory, practice and rules of classification of living and extinct organisms.Nomenclature is the “allocation of scientific names to the units a systematist considers to merit formal recognition.” (Hawksworth et al., 1995. The Dictionary of the Fungi).,Nomenclature,The nomenclature of fungi is governed by the International Code for Botanical Nomenclature, latest edition 1994, as adopted by the International Botanical Congress.,Hierarchical ClassificationKingdom Fungi Phylum Basidiomycota Class Basidiomycetes Order Agaricales Family Agaricaceae Genus Agaricus Species: Agaricus campestris L.(蘑菇),Agaricus campestris L.,Agaricus campestris L. is the type species of the genus Agaricus L.campestris is the specific epithetNote that the genus and species are in italics (or underlined); the genus is capitalized, the species epithet is in lower caseL. stands for Linnaeus, the authority,Agaricus bisporus (Lange) Imbach,Lange and Imbach are the authorities for this speciesLange was the first to describe this fungus, as Coprinus bisporusImbach later transferred the species bisporus to the genus Agaricus,二孢蘑菇,Authority the author of a scientific name of a taxon; the person/persons who formally described and published the name. What if there are several mycologists named Lange, how do we know which one did the work?Standard abbreviations of authority names can be found in the Dictionary of the Fungi (Hawksworth et al. 1995) and Fungi on Plants and Plant Products in the United States (Farr et al. 1989).,What is a species?,Most fungi are morphospecies（形态种）, delimited on the basis of phenotype, most commonly by morphological characters, and represented by a type specimen. A biological species（生物学种） is “a population, or a group of populations, among which there is interbreeding. Two individuals might not be able to interbreed, but they are still members of the same species (conspecific) if they are part of the same gene pool.” ( Futuyma, D.J. 1998. Evolutionary Biology).,What is a species?,A phylogenetic species（谱系物种 ） is “irreducible (basal) cluster of organisms diagnosably different from other such clusters, and within which there is a parental pattern of ancestry and descent” (Cracraft, J. 1989. Speciation and Its Consequences). （是无法再加以分割的生物基本群集(cluster)，各基本群集有其自身的“祖裔传衍模式”可与其它群集分辨开来。）,For mycologists, species concepts and species recognition are problematic. John Taylor and colleagues have proposed a recognition concept that is rapidly gaining popularity among mycologists using a phylogenetic approach. This concept is termed “Genealogical Concordance（系谱和谐) Phylogenetic Species Recognition” (GCPSR) and encompasses a phylogenetic approach based on concordance (agreement) of multiple gene genealogies (Taylor et al., 2000. Fungal Genetics and Biology 31: 21-32).,真菌的起源与演化,一些学者根据真菌有性阶段的形态及交配方式进行推测，认为真菌来自藻类。壶菌目自原藻演化而来；水霉目自无隔藻演化而来；毛霉自接合藻演化而来；子