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Systemic classification of zygomycota and blastocladomycota
- 1. WELCOME
- 2. Classification of Blastocladiomycota and Zygomycota (kirk et al., 2008) Harish J PAMB1087 Department of Plant Pathology UNIVERSITY OF AGRICULTURAL SCIENCES,GKVK, BANGALORE
- 4. General Characteristics Members occur saprophytically in water or plant debris or soil The thallus is eucarpic or holocarpic, rhizoidal system is common Posteriorly uniflagellate zoospores are produced as asexual spore Sexual reproduction: isogamous or anisogamous Alternation of generation is common. Presence of gamma particles A prominent nuclear cap is found in zoospores and planogametes. Zoospores
- 5. Blastocladiomycota Blastocladiomycetes Blastocladiomycetales Blastocladiaceae Catenariaceae Coelomomycetaceae Physodermataceae Sorochytriaceae Allomyces Blastocladia Blastocladiella Blastocladiopsisa Microallomyces • Catenaria • Catenophlyctis • Coelomomyces • Coelomycidium • Callimastix • Physoderma • Urophlyctis Sorochytrium Domain - Eukarya Kingdom - Fungi Phylum Class Order Family Genus (Kirk et al., 2008)
- 6. Genus: Allomyces • Allomyces was first discovered in India in 1911 by E.J. Butler, they exist in soil and water as saprobes. • Septa are absent except at the bases of reproductive organs and older hyphae. • The female gametangium produce a pheromone called sirenin which attracts the male gametes. • The female gametes are sluggish swimmers and tend to remain near gametangium following release allowing male gametes to find female gametes for fertilization. • Male gametes also produce female attracting pheromone called parisin.
- 7. Allomyces macrogynus - Alternation of generations
- 8. Genus: Physoderma • All members of this genus are obligate parasites of vascular plants • Magnus, in 1901, used characteristics of the resting spore and host plant reaction to distinguish between Physoderma and Urophlyctis, he claimed that resting spores from Physoderma were globose and ellipsoidal, and those from Urophlyctis were flattened on one side. • Physoderma species cause discoloration and slight malformation, while Urophlycits cause significant malformation and hypertrophy.
- 9. Brown spot of maize - Physoderma maidis Crown wart of Alfalfa - Physoderma alfalfae Sugarbeet crown wart - Urophlyctis leproides
- 10. Genus: Coelomomyces • Coelomomyces produce coenocytic mycelium, naked plasmodium like thallus which lacks rhizoids. • Coelomomyces psorophorae are obligate parasites of mosquitoes and chironomids (midges) and are important biological control agents of mosquitoes. • It has an alternation of generation and also heteroecious requiring two hosts [one mosquito larvae; Culiseta inorata- sporophytic thalli diplophase (2n) and other a copepod; Cyclops venalis- gametophytic thalli haplophase (n)] similar to rust fungus in Basidiomycota. • Zygote (A) • Larva of Culiseta inornata (B) • Sporangia (C) • Zoospores of opposite mating type (D) • Cyclops vernalis (E) • Gametes of opposite mating type (F)
- 11. Abdomen of Simulium piperi with Coelomomyces.
- 12. Zygomycota Weeds of the fungal world Mostly saprobic, some are Facultative parasites Production of metabolites
- 13. General Characteristics • Thallus is well developed with branched mycelium consisting of coarse grey or white coenocytic hyphae. • Cell wall is composed of chitosan, chitin, a partially deacetylated form of chitin. • Tufts of rhizoids (hold-fasts) are formed as anchoring organ just below the sporophore. • The intervening hypha connecting two groups of rhizoid are called stolon. • Asexual reproduction by aplanospores (non-motile sporangiospores), conidia (Entomophthorales); also by budding, oidia, arthrospores and chlamydospores. • A typical zygomycete sporangium is relatively large usually columellate borne terminally on a specialized hypha called sporangiophore. • Sexual reproduction results in thick walled resting spore called zygospore; developed within a zygosporangium which is formed after a fusion of two gametangia.
- 14. Zygomycota Domain - Eukarya Kingdom - Fungi Phylum Subphylum Family Genus Mucoromycotina Kickxellomycotina Zoopagomycotina Entomophthoromycotina Zygomycetes Trichomycetes Mucorales Endogonales Entomophthorales Mucoraceae Pilobolaceae Endogonaceae Mucor Rhizopus Pilobolus Endogone Order Class Entomophthoraceae Entomophthora Class Order Family Genus Genus (Kirk et al., 2008)
- 15. Mucorales • Fungi in this order are widely distributed in soils and mostly saprobes; some may cause spoilage of food. • Some are facultative parasites of plants and animals, while others may be obligate parasites on other fungi, especially on other Mucorales and mushrooms. • Mucorales are commonly known as ‘pin molds’ because of their sporangia that appear as black dots in the cobweb-like hyphae, are often the first species that participate in decay of vegetable matter and other substrate, hence called “sugar fungi”. • They utilize simple sugars most efficiently leaving complex polysaccharides (cellulose, hemicelluloses, pectin etc.) as they lack enzymes to degrade complex carbohydrates. • The phenomenon of heterothallism was discovered by an American mycologist/geneticist Dr. A.F. Blakeslee in 1904 in Mucorales (Mucor mucedo and M. hiemalis) • The pheromones initiating sexual development in Mucorales are mating- type specific and function as precursors of compounds known as trisporic acids.
- 16. Family: Mucoraceae • This is one of the largest families of Mucorales. • It contains genera Actinomucor, Mucor, Rhizomucor, Rhizopus, Parasitella, Zygorhynchus and Circimucor. • Members are either homo or heterothallic and produce multispore columellate sporangia with persistent walls. • Species of Mucor and Rhizopus cause post harvest rot in fruits and vegetables. Ex: R. atrocarpi causes fruit rot of Jack fruit • Rhizopus stolonifer occurs very frequently on bread and hence called Bread mould. • Due to pin head like black coloured sporangia the entire mycelium appears blackish and hence the name “Black mould”. • Mucormycosis is caused by M. circinelliodes, M. javanicus, M. racemosus, M. ramosissimus and M. spinosus.
- 18. • Some of species cause soft rot of sweet potato Rhizopus stolonifer (Black rot of sweet potato) in storage. • Choanephora cucurbitarum is plant pathogenic that attacks flowers and fruits of cucurbits and many other economically important plants often causing considerable damage (rotting of green vegetable peas, beans, cucumbers etc). • Rhizopus stolonifer can also be very destructive to strawberries during shipping and marketing. • Mucor racemosus causes storage rot of fruits and vegetables. Structure of Rhizopus
- 19. Rhizopus arrhizus Rhizopus microsporus Rhizopus stolonifer
- 20. Mucor Rhizopus 1. Habitat: commonly found on dung Commonly found on bread 2. Structures like rhizoids, stolons are absent Structures like rhizoids, stolons are present 3. Sporangiophores variously branched with a single terminal columellate sporangium Sporangiophores unbranched, short, stout with single terminal columellate sporangium 4. Gametangia are of same size Gametangia are of unequal size 5. Food material is absorbed by entire mycelial surface Food material is absorbed by rhizoids 6. Aplanospores adhere to columella with drop of fluid, not easily disseminated but disseminated by insects and ants. Aplanospores easily disseminated by wind 7. Columella do not change its shape after spore liberation Becomes dome shaped after spore release
- 21. Family: Pilobolaceae • It includes three carpophilus genera, Pilobolus ( Hat thrower, shot gun fungus or Circardian clock), Pilaira (isolated from dung of herbivores), Utharomyces (from rodent faeces), rarely found in soil. • All species produce phototrophic, unbranched sporangiophores that arise directly from the substrate and terminate in dark flat columellate sporangia with persistent cutinized walls covered with crystals, probably composed of calcium oxalate. • Pilobolus has a growth requirement of dung extract and it is unique in Order Mucorales for its forcible discharge of sporangium for a distance up to 2 m or more.
- 23. Order-Endogonales • Formerly this order included the forms that were both saprobic and mycorrhizal, however, the endomycorrhizal taxa now belong to Glomales. • Endogonales contain single family Endogonaceae containing genera Endogone and Sclerogone. The sporocarps contain only zygospores and sporangia are unknown. • The sporocarps of Endogone has distinct odour of onions, burnt sugar or fish. • Both genera can be found in soil, rotting wood, sphagnum or other plant material as saprobes or ectomycorrhizal associates. Sporocarp of Endogone pisiformis Zygospores of E. pisiformis
- 25. Subphylum : Entomophthoromycotina • Encompasses a group of biologically important fungi best known as insect pathogens. • But many are saprobic in soil, litter and dung and one genus is parasitic on gametophytes of ferns. • The host specificity and relatively rapid killing of hosts makes Entomophthorales important biocontrol agents. • Mycelium divided by septa turns into uni- or multinucleate segments termed as hyphal bodies. • Sexual reproduction involves the union of two hyphal bodies and form thick bi- layered zygospore. Entomophthorales
- 26. Entomophthora • A familiar species Entomopthora muscae, commonly called Fly fungus, found on dead house fly, causes ‘Fly cholera’. • Healthy flies contact the sticky conidia and get infected. • Entomopthora maimaiga is used as a biocontrol agent against gypsy moths
- 27. THANK YOU
Editor's Notes
- Exception : Coelomomyces resides as obligate parasite in mosquito larvae. Haploid gametothallus alternated to sporothallus (diploid) then it undergoes meiosis and again forms gametothallus. , it is the only order having nuclear cap in the zoospores and planogametes
- Thus exhibit haplodiplobiontic life cycle
- Zygote (A) infects larva of Culiseta inornata (B) leading to development of hyphal bodies, mycelium and, ultimately, thick-walled resistant sporangia. Under appropriate conditions these sporangia (C) release zoospores of opposite mating type (D) which infect the alternate host, Cyclops vernalis (E). Each zoospore develops into a thallus and, eventually, gametangia. Gametes of opposite mating type (F) fuse either in or outside of the copepod to form the mosquito-infecting zygote