Presentation on theme: "Fungus-Like Protozoans Mycology (Bio 594, Special Topics) M. Marshall 2013 Shippensburg University (See last slide for credits)"— Presentation transcript:
Fungus-Like Protozoans Mycology (Bio 594, Special Topics) M. Marshall 2013 Shippensburg University (See last slide for credits)
Carl Linnaeus (1707-1778) the “ Father of Taxonomy ” –“ Minerals exist; plants exist and live; animals exist, live and sense. ” – Plants without obvious sexual organs were classified in Class Cryptogamia (lichens, fungi, mosses, ferns) Fungi are primitive plants under this classification of organisms. @
Two Kingdom System In the not-so-distant past all life was considered to be either plant or animal @
Modern Classification At least 7 kingdoms are now recognized: – Eubacteria, Archaebacteria, Animalia, Plantae, Eumycota, Stramenopila (Chromista ?), Protoctista (Protozoa, Protista) – Some proposed revisions split the protozoans up into even more kingdoms (see slide after next) – The kingdoms shown in Blue contain fungus-like organisms, some of which (now in the Stramenopila ?) were considered true fungi until relatively recently.
The seven Kingdom system according to your text (now outdated) Kingdoms in Blue contain fungi or fungus-like organisms
The evolution of “large scale”systematics has been substantial, but things are still a mess at present
The problem with Protozoans It seems clear that the Protozoa as they are now constructed, which in itself has always been controversial, will not stand. The relationships among members of this kingdom are in some case so remote that it seems almost certain that it will eventually be fragmented into several more Kingdoms. There is a fair amount of consensus that the Chromistids should exist as a distinct Kingdom separate from protozoans, and that the Oomycete “watermolds” should be placed there instead of in their former position (along with the Zygomycetes) in the Phylum Phycomycota. So the Pythiums, Phytophthoras, Saprolegnias, Peronosporales and so on – all of which have aquatic motile zoospores – are no longer considered true fungi. The other protozoan category of fungus-like organisms has always been considered protozoans; these are the free-living plasmodial and cellular slime molds and the Plasmodiophorids, which are slime mold – like obligate endoparasites of plant roots. These are placed in theEumycetozoa of the Amoeboza as the cells move via cytoplasmic streaming.
A (doubtless out of date) Historical Overview PROTOZOANSEUMYCOTA (True fungi) Chromista ? Phycomycetes * Phythophthora Oomycetes Pythium Plasmopara Peronospora (moved) ZYGOMYCOTA* (incl. Glomeromycota) Amoebozoa MYXOSTELIDA CHYTRIDIOMYCOTA* (Myxomycetes) (Blastocladiales, true Chytrids plasmodial slime molds and others) DICTYOSTELIDA ASCOMYCOTA* (Acrasiomycetes) cellular slime molds BASIDIOMYCOTA* PLASMODIOPHORA All OTHER PROTOZOAN GROUPS Deuteromycetes* (artificial Form Phylum & subdivisions based on asexual structs. only) * all ended in – cetes and were considered classes; grayed out = no longer a valid taxa zoospores swarm cells amoeba zoospores Sex = zygospores Sex = ascospores Sex = basidiospores Sex = oospores
At the moment (2013) things look like this... From the Tree of Life web projecthttp://tolweb.org/tree/phylogeny.html
Physarum polycephalum, a plasmodial slime mold Contrast to Fig 2.1 in BK Fifth Kingdom book
Physarum plasmodium, essentially one huge multinucleate cell
Plasmodia differentiate into a colony of sessile fungus-like sporangia Myxomycetes are classified according to the structure of the sporangia. In some the differentiation into delicate stalked structures is quite complex, in others the plasmodium seems to merely collect itself a bit and harden in place Hemitricia clavata
Myxomycota sporangia A & B Sporangia of Arcyria and Stemonitis C. An aethalium (no stalk) of Lycogola spp. D. a plasmodiocarp (the plasmodium veins thicken and harden of Hemitrichia spp. (thanks to Tom Volk, http://botit.botany.wisc.edu/toms_fungi/oct2003.ht ml) http://botit.botany.wisc.edu/toms_fungi/oct2003.ht ml Trichia spp. sporangia
Dictyostelium discoideum, a cellular slime mold Contrast to Fig. 2.2 in BK
Dictyostelium amoeba aggregate to form a slug that then differentiate into a single stalked sporangium or sorocarp
Dictyostelium aggregation / differentiation stages in sorocarp formation
From: Schaap, P. 2011. Evolutionary crossroads in developmental biology: Dictyostellium discoidium. Development 138: 387-396 The biochemistry and molecular biology of Dictyostelium aggregation and sporulation has been extensively investigated.
Plasmodiophora brassicae, clubroot of crucifers. Plasmodiophora is a genus in the Phytomyxea of the Protist Rhizaria super group. P. brassicae infects over 300 varieties of crucifers world-wide. It’s an obligate, holocarpic (the whole plasmodium differentiates into spores), endoparasite. Infections cause host cell hypertrophy with loss of tissue integrity and function; above ground wilting and yield loss results. Clubbed root Spores filling cell remnants