Some important Ascomycetes Taphrina deformans Peach leaf curl

Some important Ascomycetes Taphrina deformans - Peach leaf curl Unusual ascomycete 1, . Naked asci 2. Extensive dikaryophase 3. Anamorph has budding cells 1. Pathogens

Some important Ascomycetes Fusarium sp. Anamorph genus Teleomorphs are in Gibberella and Nectria Wilt diseases Several economically important diseases - e. g. on cereals, peas, beans. Causes greatly reduced yield/ death. Can live in soil for many years as saprophytes.

Some important Ascomycetes Cryphonectria (Endothia) parasitica causes Chestnut blight, Ophiostoma ulmi causes Dutch elm disease which was introduced into the U. S. in 1930, to Canada in 1944 These two diseases have all but wiped out Chestnut and Elm in N. America

Some important Ascomycetes Soft rots in family Sclerotiniaceae e. g Monilia Sclerotinia Botrytis growing on overripe grapes causes a ‘noble rot’ - increases sugar content and makes a sweet, highly valued wine. . Most produce dense masses of melanized hyphae (termed sclerotia) to overwinter

Some important Ascomycetes Cordyceps sp. Attack insects - sporulate directly on their dead bodies. Important as the anamorph of some is: Tolypocladium niveum - source of cyclosporine, the most effective and least toxic immunosuppressant

Some important Ascomycetes Life cycle of Ergot fungus Claviceps purpurea.

Some important Ascomycetes Erysiphales. Powdery mildews. Important diseases of grapes, hops, gooseberries and cereals. Produce cleistothecia some have specialized opening mechanisms. Conidia form white ‘mat’ on leaf surface

Some important Ascomycetes Penicillium /Aspergillus. Penicillium antibiotics Aspergillus mycotoxins eg aflatoxin Also important in ‘blue cheese’ production & as food rots

Some important Ascomycetes Venturia inaequlis Apple Scab

Some important Ascomycetes Drechslera maydis - Southern corn blight - one of the most serious outbreaks of plant disease in recent years (1970) • `Texas male sterile' strain of corn was widely used for seed production - highly susceptible to this fungus (previously a minor disease). • Toxin disrupts mitochondrial membranes. • Toxin also reduces p’synthesis: inhibits uptake of K in stomates, causing the stomates to close and reducing the intake of CO 2.

Some important Ascomycetes 2. Food and Health EDIBLE SPECIES Truffles - Tuber sp. A hypogeous (undergound) fruit body - many internal asci attracts animals to dig it up and eat it - so liberating ascospores. Morels Morchella sp.

Some important Ascomycetes • Saccharomyces cerevisiae - ‘yeast’ – Baking and brewing use. – Yeast extract (Marmite)

Ascomycetes - yeasts • Yeasts are fungi which typically form unicellular cells which divide by budding i. e not filamentous hyphae • Most are Ascomycetous - many form asci, but there are some yeast-like forms in the Zygomycetes and Basidiomycetes • Budding yeast cells considered to be conidia • • Very important in ecology and for man (brewing and baking) Yeasts will be dealt with later by Dr. Lachance.

Some important Ascomycetes 3. Rots and decomposition • Ascomycetes include fungi which are: – prime colonizers/decomposers of soft plant debris, – play vital role in the carbon and nitrogen cycles. – dominate soil mycota in most forests. – dead leaves colonized by aquatic hyphomycetes tolerant of low temp’s - can grow even under ice – make dead leaves more palatable and nutritious for the detritivorous invertebrates which eat them. – Cellulolytic hyphomycetes - cause blue stain and soft rot of wood, discolouration and loss of strength of cotton materials and moulding of almost any damp organic substrate.

Some important Ascomycetes 4. Genetics/ Biotechnology • Classical genetics - Yeast, Sordaria, Neurospora • Molecular Genetics - yeasts and filamentous fungi used as hosts for vectors carrying genes from eukaryotic organisms. E. g. used to express insulin, human growth factor, human tissue plasminogen activator (used to dissolve blood clots) etc. • Penicillium and many other fungi - source of penicillin & other antibiotics.

4. Genetics/Biotechnology Contributions to classical genetics Ascomycetes made major contributions to the study of meiotic recombination - asci contain products of one meiosis in an order reflecting segregation of alleles at first and second division. Ascomycetes also important in study of mitotic recombination via a parasexual cycle.

Follow-up to Lecture • • • Read Chap 4 (38 -45), (52 -53). Skim read rest of chapter. View Fifth Kingdom CD/ Web page (Chap 4) Review lecture notes on Web know main features of Ascomycete fungi Important economic species review terms • ascospores/ascus/ascoma ; operculate/inoperculate • unituniculate/bituniculate/prototuniculate • apothecia/perithecia/cleistothecia • conidia/conidiophore/conidioma • dikaryophase