BIOLOGY 3404 F EVOLUTION OF PLANTS Fall 2008

BIOLOGY 3404 F EVOLUTION OF PLANTS Fall 2008 Lecture 5 Thursday October 2 Chapter 14, Fungi (part I)

Outline • Life cycles: three types cover almost all e. g. s • Groups of fungi and fungus-like organisms and what they do • Fungus-like Protists: Myxomycota, Dictyosteliomycota, Oomycota, etc. • Five Phyla of Kingdom Fungi: Chytridiomycota, Zygomycota, Glomeromycota, Ascomycota, Basidiomycota • Unnatural groups: Deuteromycetes, Lichenomycota

Zygotic Meiosis, Raven et al. Fig. 12 -15 a

Gametic Meiosis, Raven et al. Fig. 12 -15 b

Sporic Meiosis, Raven et al. Fig. 12 -15 c

Which is it? (Which are we? ) • Knowing Fig. 12 -15 inside-out will make life-cycles in this course much easier to manage • We will see a lot of life cycles, but in essence there are only three kinds: recognized by ploidy of the organism – Haploid: zygotic (meiosis immediately follows formation of the diploid zygote) – Diploid: gametic (meiosis occurs in single cells of diploid individual, long after zygote formation; meiosis produces gametes, which unite to form zygote) [= delayed meiosis] – Both haploid and diploid individuals: sporic (meiosis occurs in single cells of diploid individual, long after zygote formation; meiosis produces spores, which form haploid individuals) [= delayed production of gametes]

But remember … • Many organisms reproduce asexually, so their life cycles do not fit in any of the three types described above. • Most asexually-reproducing organisms are derived from sexually-reproducing ones, so you can infer what type of life cycle their ancestors had • Some asexually-reproducing organisms may be “primitively asexual” - i. e. , they have been around since before sex was invented

[Fungus-like Protists I: the slime moulds, Myxomycota and Dictyosteliomycota] – FYI only • Closely related to amoebae; spores germinate to form amoeboid stage in life cycle • Engulf food (phagocytosis) but may also have external digestion via secreted enzymes, followed by absorptive nutrition (as in Fungi) • Amoebae aggregate (c. AMP) and form acellular plasmodium (Myxos) or cellular pseudoplasmodium (Dictyos): “feeding slime”

Slime Moulds II • Following nutritional or other environmental trigger(s), feeding slime transforms into fruiting (spore-producing) structures – very fungus-like, and very beautiful • See George Barron’s Myxo web site, http: //www. uoguelph. ca/~gbarron/myxoinde. htm • Very important as nature’s vacuum-cleaners – eating particulate organic matter, bacteria and spores, and contributing to nutrient cycling • Very common in soil and litter

Arcyria cinerea (Photos: GL Barron) Badhamia utricularis Dictydium cancellatum

Myxomycete life cycle, Raven et al. Fig. 15 -58 Is this zygotic, gametic, or sporic meiosis?

Dictyostelid life cycle, Fig. 15 -60

Fungus-like Protists II: the water moulds, Oomycota • These are closely related to Chrysophyta and others in the group sometimes called Kingdom Stramenopila (or Heterokonta) • Have motile cells (zoospores) with two flagella, one tinsel and one whiplash • Oomycota include some saprotrophs but also some important plant pathogens, such as Late Blight of Potato (Phytophthora infestans), Blue Mould of Tobacco (Peronospora destructans), and Downy Mildew of Grapes (Plasmopara viticola)

Late Blight of Potato, Raven et al. Fig. 15 -19 Tinsel and whiplash flagella; Kendrick 5 th Kingdom

Oomycota life cycle, Raven et al. Fig. 15 -17

(true) Kingdom Fungi Defined • Heterotrophic, eukaryotic organisms generally with extracellular digestion and absorptive nutrition; cell walls contain chitin and glucan/mannan, not cellulose • Most are filamentous but some are unicellular (yeasts); a few are motile • Must either live as saprotrophs (decaying dead organic matter) or symbionts (parasites or mutualists, etc. , with other living organisms

Chytridiomycota • Approximately 1000 described species • Depend on free water - flagellate • Most groups have just one flagellum, and can be recognized as chytrids by this • Some (the rumen fungi) have multiple flagella, and were considered protozoa • Synchytrium endobioticum causes potato wart disease, closed US to PEI potatoes.

Chytrids II • Closest to ancestral choanoflagellate, the common ancestor of both fungi and multicellular [= true] animals – Fig. 15 -7 • At least some have sexual and asexual phases, and also haploid and diploid phases in their life-cycle (Allomyces) – Fig. 14 -10

Allomyces life cycle, Raven et al. Fig. 14 -10 Is this zygotic, gametic, or sporic meiosis?

Chytridiomycota Catenaria, a chytrid that attacks and consumes living nematodes (drawing by George Barron)

Glomeromycota • Approx. 150 described species • Thought to be 300 -500 M years old! • These were formerly [i. e. , in your textbook] treated in Zygomycota as the Glomales • The entire group (or what we know of them) form symbioses with photoautotrophs • Entirely asexual (? ) – for millions of years, but coenocytic, with different nuclei

Glomeromycota II • One species (Geosiphon) has an endosymbiotic cyanobacterium • The rest form mycorrhizal relations with >80% of green plants, called “endomycorrhizae” or Arbuscular Mycorrhizae (AM) – Figs. 14 -40, 14 -44 • These relations are particularly important in delivering phosphorus to herbaceous and tropical woody species in nutrient-poor soils

Glomeromycota III Hyphae and a spore of a Glomales washed from soil. The spore is 1/10 mm in diameter!

Zygomycota • Approximately 1, 000 described species • Best known are the “bread moulds” Rhizopus and relatives (Mucorales), with tall, broad, glassy hyphae, growing on bread, fruit, and pumpkins • Broad, coenocytic hyphae, thin-walled (occasionally wall-less when growing within insects) • May have both asexual and sexual reproduction (sporangiospores and zygospores borne in zygosporangia) • May be homo- or heterothallic.

Zygomycota Rhizopus

Zygomycota Rhizopus hyphae and asexual spores Rhizopus zygospores

Zygomycota Asexual spores (sporangiospores) of Cunninghamella (photo by George Barron)

Rhizopus life cycle, Raven et al. Fig. 14 -11 Is this zygotic, gametic, or sporic meiosis?

Ascomycota • Approximately 48, 000 described species • Include most yeasts, most “deuteromycota” and most “mycophyta” or “lichenomycota” – we will return to these fungi in lectures on “lichens” • Ascomycota include many important plant diseases, as well as diseases of humans • Saprotrophs (some may be pests) degrade incredible diversity of substrates

Ascomycota Asci of a cup fungus from dung, each with eight ascospores (dark purplish brown when mature). Photo: George Barron

Ascomycete life cycle, Raven et al. Fig. 14 -14 Is this zygotic, gametic, or sporic meiosis?

Ascomycota Morels, Morchella esculenta, on a lawn in London

Ascomycota “Tar spot” of maple caused by Rhytisma acerinum

Ascomycota Ascomata Asci Powdery mildew of maple caused by Uncinula bicornis

Basidiomycota • Approximately 30, 000 described species • Include most mushrooms, most major wood decayers, and most mycorrhizae of boreal trees (ectomycorrhizae – more next week) • Basidiomycota include many important plant diseases, including rusts and smuts • Attine ants and termites cultivate saprotrophic mushrooms

Basidiomycota The “sexual cell” in Basidiomycota is the basidium (pl. basidia). Two different haploid nuclei are present in every cell – the dikaryon, and then fuse to form a short-lived diploid nucleus in the basidium.

Mushroom life cycle, Raven et al. Fig. 14 -18 Is this zygotic, gametic, or sporic meiosis?

Clamps and dolipores

“Deuteromycota” – a fictitious group* Penicillium, an asexual Ascomycete *Your text now calls them “conidial fungi”

Penicillium (above) and Aspergillus (right)

“Lichenomycota” • Also called the Mycophycomycota, but are a completely fictitious group • Lichens (more next week) have evolved many times in many groups of Ascomycota (most) and some groups of Basidiomycota (few)