ASCOMYCETES (CONT.) PYRENOMYCETES I IB 371 General Mycology Lecture 22 Tuesday November 11, 2003

ASCOMYCETES (CONT.) PYRENOMYCETES Ascomata perithecial or sometimes cleistothecial Ovoid to cylindrical unitunicate asci, usually formed from ascogenous hyphae and croziers in a hymenium or becoming scattered throughout the ascomata Hamathecial tissue present or absent at maturity

PYRENOMYCETES Asci persistent or evanescent Ascospores usually forcibly discharged from persistent asci Ascospores comprising a wide range of morphologies Asexual reproduction by conidia

PYRENOMYCETES Include numerous and important plant pathogens Parasites and symbionts of arthropods Saprophytes capable of degrading lignocellulose Endophytes of a variety of plants Mycotoxin producers Etc.

In-class Activity

XYLARIALES - ASCOMATA Dark, leathery or carbonaceous Usually a perithecium but sometimes a cleistothecium Sometimes embedded in a stroma

Stromata

XYLAIALES - ASCI Formed in a peripheral or basal hymenial layer Usually cylindrical, sometimes club shaped or subglobose Usually with an apical ring surrounding a pore through which ascospores are discharged Apical ring may be amyloid and stain blue in iodine

XYLARIALES - HAMATHECIUM Paraphyses present - attached at base, growing upward and inward, and interspersed among the asci Periphyses present in the beak of the perithecium

XYLARIALES - ASCOSPORES Usually pigmented One celled or sometimes transversely septate With germ pores or slits Sometimes with a gelatinous sheath

XYLARIALES - ANAMORPHS Mostly holoblastic development with conidiogenous cells proliferating sympodially or percurrently

Hypoxylon multiforme

Hypoxylon ascospores

Xylaria stroma

Xylaria asci

Xylaria asci

XYLARIALES Remember Xylaria polymorpha – dead man’s fingers

SORDARIALES Primarily saproprobic on plant or animal remains, dung Ascomata rarely in a stroma Ascomata perithecial or cleistothecial Peridium thin or thick, transparent to darkly pigmented

SORDARIALES Asci cylindric to club-shaped with apical pores and often some type of apical apparatus Paraphyses may or may not be present at maturity Ascospores various in pigmentation and septation

Sordaria fimicola Used extensively for genetic studies Found on dung (fimicolous) Color mutations in ascospores used as markers in genetic studies Beaks are positively phototrophic and direct forcibly shot ascospores away from the substrate

Sordaria

Podospora on dung

Podospora

Cercophora alleghensis

CHAETOMIUM Ubiquitous Cellulose decomposers Mesophilic, thermotolerant, thermophilic species Tooth paste fungus

CHAETOMIUM Perithecia ostiolate, covered with hairs Asci thin-walled, evanescent Ascospores lemon-shaped w. apical or sub-apical germ pores Conidia, when produced, chlamydospores or phialospores

CHAETOMIUM - PERITHECIA

CHAETOMIUM

CHAETOMIUM

CHAETOMIUM

Neurospora crassa Gets its name from the nerve-like striations on the ascospores Used extensively in genetic studies (1 gene for 1 enzyme theory - Beadle & Tatum) Field of haploid genetics - all genotypes expressed Lab pest - very fast growth and conidiation rate, conidia hydrophobic & easily dispersed

Halosphaeriales Occur primarily in seawater with some species in freshwater habitats Ascomata membranous or carbonaceous Hamathecium absent or as catenophyses Asci thin-walled, usually without apical structures, deliquescing to release ascospores Ascospores modified for dispersal & attachment in aquatic habitats

Ascospore appendages

HALOSPHAERIALES

HALOSPHAERIALES

HALOSPHAERIALES

Corollospora lacera

HALOSPHAERIALES

Nais glitra ascus

Nais glitra ascospores