Introduction to the Basidiomycetes

1. Introduction to the Basidiomycetes Mycology (Bio 594, Special Topics) M. Marshall, 2013 Shippensburg University (See last slide for additional credits)

2. The Basidiomycetes

3. Phylum Basidiomycota “Basidiomycetes” characterized by basidiospores formed on basidia (sing. basidium) Three subphyla (classes?) recognized Agaricomycotina (=Hymenomycetes) Ustilaginomycotina Pucciniomycotina(=Urediniomycetes)

4. Kendrick book (an example of an older system) Phylum: Dikaryomycota Sub phy: Basidiomycotina Class: Holobasidiomycetes Order: Exobasidiales – odd resupinate “crusts” Order: Dacrymycetales – Jelly fungi Order: Aphyllophorales – lage (400+ genera) no gills Fam: Corticicaceae – resupinate “paint fungi” on wood Fam: Thelephoraceae - resupinate “paint fungi” on ground Fam: Clavariaceae – Club & coral fungi FamCantherellacea - Chanterelles Fam: Coniophoraceae – dry rots Fam: Hydnaceae – tooth fungi Fam: Schizophyllaceae – stalkless gilled on wood (common) Fam: Polyperacea – brackets & shelfs, many difficult to classify Order: Agaricales Fam: Amanitacea - Amanitas Fam: Bolbitacea – Boletes Fam: Coprinaceae – Coprinoids FamCortinariaceae – partial veil ETC

5. Agaricomycotina Mushrooms, puffballs, shelf fungi, jelly fungi Ustilaginomycotina Smut fungi and allied taxa Pucciniomycotina Rust fungi and allied taxa

6. Basidiomycete Mycelium Primary mycelium (monokaryon) Secondary mycelium (dikaryon) Characterized by clamp connections in many taxa Tertiary mycelium organized, specialized tissues that make up the basidiocarp

7. Basidiomycotaseptal pores Dolipore septa, septal pore caps or parenthosomes Septal pore cap

8. Septal Pore comparisons

9. Clamp connections

10. The Basidiomycete Life Cycle

11. Most are heterothallic 20-25% of heterothallic taxa are unifactorial (bipolar); 65% of heterothallic taxa are bifactorial (tetrapolar) with A and B loci Model systems for mating loci: Ustilagomaydis (corn smut) Schizophyllum commune Coprinus cinereus These systems have been explored at the molecular level and have proved to be quite complex. Sexual compatibility in Basidiomycetes

12. Alocus Two closely linked subloci(Aα) and (Aβ) or (A1 andA2)with multiple alleles are expressed as a functional unit and any cross involving strains differing at either Aα or Aβis compatible. In S. commune, Aαhas 32 alleles, Aβhas 9 alleles Note* the specific alleles present are not as important as the sub-loci type! Alocus controls: Specific nuclear pairing Initiation of clamp Separation of clamp by septum Compatibility at A locus only gives barrage reaction: Nuclear pairing and initiation of clamp only The A locus

13. Blocus Two closely linked sub-loci (Bα) and (Bβ) with multiple alleles are also expressed as a functional unit and any cross involving strains differing at either Bα or Bβ is compatible In S. commune, Bα and Bβ have 9 alleles each B locus controls: Septal breakdown (last stage of clamping) Nuclear migration Compatibility at B locus only gives flat reaction Nuclear migration occurs, but no clamp initiation The B locus

14. Two genetic loci (A and B) are located on separate chromosomes and segregate separately at meiosis Mating reactions of four possible isolates of a bifactorial fungus: Bifactorial (tetrapolar) Mating System Barrage = death occurs in the anastomosing cells creating a clear zone between mycelia Flat = irrregularheterokaryon

15. Dikaryon formation in Coprinus and Schizophyllum requires that both A and B be different at one sub-locus in the two anastomosing hyphae. When anA1interacts with an A2 the Afunctions are “turned on” and nuclear pairing, conjugate division, clamp initiation and clamp septationall function. None of these occurs when the As of the two mycelia are the same. Similarly, when a B1 from one hyphae interacts with a B2 from the other, nuclear migration and clamp tip fusion work as they should. All Aand B functions must work for successful dikaryon formation; fusion only Multi loci control of Basidiomycete Mating by tetrapolar heterothallism

16. Common A, Bdifferent; irregular n~n= Flatrxn, no basidiospores A&Bbothdifferent Successful n+n= basidospores eventually result. Possible Mating Reactions Common B irregular n~n= Barrage, anastomosed cell death Common A&B, no n+nat all n+n= regular heterokaryon, synchronous nuclear division w clamps. n~n = nuclear ratio not 1:1, no clamps.

17. Common A, B different; irregular n~n= Flatrxn, no basidiospores A&B both different Successful n+n= basidospores eventually result. Common A, B different; irregular n~n= Flatrxn, no basidiospores A composite view

18. Basidia Basidioles Cells resembling basidia that have not produced basidiospores Cystidia Larger than other hymenial elements Variety of shapes—taxonomically important Function not known Trap air, aid in evaporation, protect basidia? The Basidiomycete Hymenium

19. Types of basidia

20. Basidium & basidiosporedevelopment

21. Basidiospore discharge Hilar appendix Film of water on spore sterigmata Buller drop

22. Agaricomycotina Mushrooms, puffballs, shelf fungi, jelly fungi Ustilaginomycotina Smut fungi and allied taxa PucciniomycotinaRust fungi and allied taxa We will next consider the rusts and smuts which have multi-celled relatively primitive basidia.

23. Credits This presentation has been modified from one posted on the web by Dr. Lori Carris, Washigton State University Plant Pathology Dept. from her course: Plant Path 521, Mycology.