Dikaryomycota Persistent dikaryon cells with two haploid nuclei

Dikaryomycota • Persistent dikaryon: cells with two haploid nuclei • Regularly septate hyphae

Dikaryomycota – two haploid nuclei Haploidy nuclear condition, referring to number of chromosome copies per cell in G 1 S G 2 M

Dikaryomycota – two haploid nuclei Nuclei: Haploid Dikaryotic plasmogamy ? Diploid karyogamy

Dikaryons in fungi • Only one cell – Zygomycetes • Limited dikaryon – Ascomycetes • Persistent dikaryon – Basidiomycetes

dikaryon monokaryon

Maintaining the dikaryon state • Conjugate mitosis – coordinated nuclear division • Typically at “clamp connections” that have specialized septa

Simple septum vs Dolipore septum

Dikaryomycete classes based on sexual sporulation • Ascomycetes in sacs • Basidiomycetes on stalks

Ascomycete life cycle Asexual cycle: haploid spores (n) +/– mating types septate hyphae (n)

Ascomycete life cycle, Raven 15 -14 Asexual cycle: haploid spores (n) +/– mating types septate hyphae (n) Mating structures: ascogonium trichogyne antheridium plasmogamy Trichogyne growth Nuclear migration

Ascogonia and antheridia T An As

Ascus development germination meiosis II mitosis (sp dep) meiosis I karyogamy 2 n crozier

Ascus formation Crozier = hook penultimate cell karyogamy Meiosis and mitosis in developing ascus

Ascus development karyogamy meiosis II mitosis

Ascomata: four types Peziza Morchella Emericella Erysiphe Neurospora Magnaporthe Cochliobolus Note ascus shape: elongate vs spherical

Elongate asci: 2 types unitunicate bitunicate operculum pore Cleistothecial asci

Asci and ascospores Peziza Eurotium Otidea

Ascoma development Ascogonium croziers dikaryotic ascogenous hyphae (n+n) Sterile Hyphae (n) Ascogonium

Ascomycete fruiting bodies: ascomata apothecium perithecium

Mycosphaerella pseudothecia

Erysiphe graminis

Holobasidia Synchronous spore formation Heterobasidia Asynchronous spore formation basidiospore sterigma septa Nuclei migrate through the sterigma/spore junction

Mushroom life cycle 15 -19 Dikaryotic hyphae Basidiomata initiation is triggered by environmental conditions, including moisture

Mushroom development Hymenium – fertile layer Mushroom hymenium on: _____, _____

Gilled mushrooms Agaricales Lactarius indigo

Pores are lined with basidia

Fomes fomentarius

Auriscalpium vulgare Hydnum repandum

Deuteromycetes – life without sex

Deuteromycetes – life without sex • Advantages – speed (of reproduction, ~1 day) – flexibility (can maintain a well-adapted genome) – can maintain (lethal? ) mutations in haploid nuclei, since hyphae are multinucleate