Mycorrhizal association in Plants

Mycorrhizal association present in plants and their types.

1. Mycorrhizal Association in Types in plants Zohaib ul Hassan BAGF11E073 Plant Pathology 8 th [email protected] University College of Agriculture, University of Sargodha, Punjab, Pakistan

2. Symbiosis Symbiosis is defined broadly as “two or more organisms living together” and in most cases both partners benefit (Lewis 1985). M ycorrhizal associations and parasitic fungi have also been called symbiotic, but many scientists now only call beneficial associations symbiotic (Lewis 1985, Paracer & Ahmadjian 2000).

3. Fungal symbioses “All associations where fungi come into contact with living host from which they obtain, in a variety of ways, either metabolites or nutrients” (Cook 1977 ).

4. Mutualistic associations Mutualistic associations are a subset of symbioses where two or more different living organisms receive mutual benefits.

5. Plant-Fungal Symbioses Mycorrhizas are the most important type of symbiotic plant-fungus associations. Definition of Mycorrhizas Mycorrhizas are symbiotic associations essential for one or both partners, between a fungus ( specialised for life in soils and plants) and a root (or other substrate-contacting organ) of a living plant, that is primarily responsible for nutrient transfer. Mycorrhizas occur in a specialised plant organ where intimate contact results from synchronised plant-fungus development.

6. Classification Scheme for Mycorrhizal Associations ( Brundrett 2004) A rbuscular mycorrhizas Associations formed by Glomeromycota fungi in plants that usually have arbuscules and often have vesicles (also known as vesicular- arbuscular mycorrhizas, AM, VAM ). Host: Plant Fungi: Glomeromycota

7. Arbuscular mycorrhizas Linear VAM Associations that spread predominantly by longitudinal intercellular hyphae in roots (formerly known as Arum series VAM ). Coiling VAM Associations that spread predominantly by intracellular hyphal coils within roots (formerly known as Paris series VAM ). Beaded VAM Coiling VAM in roots, where interrupted root growth results in short segments divided by constrictions .

8. Arbuscular mycorrhizas Inner cortex VAM Coiling VAM with arbuscules in one layer of cells of the root inner cortex .

9. Ecto -mycorrhiza Associations with a hyphal mantle enclosing short lateral roots and a Hartig net of hyphae that penetrate between root cells . Cortical Hartig net hyphae penetrate between multiple cortex cell layers of short roots . Epidermal Hartig net fungal hyphae are confined to epidermal cells of short roots.

10. Orchid Associations where coils of hyphae (pelotons) penetrate within cells in the plant family Orchidaceae . E.g.; Most are basidiomycetes in Rhizoctonia  alliance

11. Ericoid Coils of hyphae within very thin roots (hair roots) of the Ericaceae . Most are Ascomycetes

12. Sub- epidermal Hyphae in cavities under epidermal cells, only known from an Australian monocot genus . Host: Thysanotus  spp. ( Laxmaniaceae ) Fungi: Unknown

13. Morphology of Mycorrhizal Associations Arbuscule of a  Glomus  species in a root cortex cell. 

14. Ectomycorrhizas Cortical Hartig net of  Pinus  ECM root.

15. Monotropoid Monotropa  root with epidermal Hartig net (H) and mantle (M) in a cross-section viewed with UV light. Roll-over - hypha projecting into an epidermal cell (arrow) in stained root section.

16. Mycorrhiza Phylum Families Anamorphs Teliomorphs References Arbuscular Glomeromycota Glomaceae, Acaulosporacae, etc. Glomus, Scutellospora, Acaulospora, etc. none Schüßler et al. (2001), Oehl and Sieverding (2004) Ecto- mycorrhiza (ECM) Basidiomycota, Ascomycota, Zygomycota Many families including Amanitaceae, Cortinariaceae, Boletaceae, etc. Most ECM fungi lack anamorphs, butCenococcum is one example Many genera includingAmanita, Cortinarius, Russula, etc. Matheny et al. 2006 and Hibbett et al. 2007 Monotropoid ECM Basidiomycota Russulaceae, etc. NA Russula, Tricholoma, Rhizopogon, etc. Bidartondo et al. 2000, Bidartondo & Bruns 2001, 2002, Leake et al. 2004 Orchid:  not myco-  heterotrophic Basidiomycota (Ascomycete) Ceratobasidiaceae, Tulasnellacea, Sebacinaceae (related to Chanterellaceae?) (also many others are reported) Sterile hyphae:Rhizoctonia alliance:Epulorhiza, Ceratorhiza, Tulasnella, etc. as well as Fusarium, etc. Ceratobasidium, Thanatophorus, Sebacina, etc. Zelmer et al. 1996, Rasmussen 2002, McCormick et al. 2004, Bayman  & Otero 2006,  Dearnaley 2007, Taylor & McCormick 2007 Orchid:  myco-  heterotrophic Basidiomycota Russulaceae, Telephoraceae, etc. NA unrelated clades of ECM, orchid and saprophytic fungi See lists by Batty et al. 2002, Bidartondo et al. 2004, Dearnaley 2007 Ericoid Ascomycota (Basidiomycota) Helotiaceae ( Sebacinaceae ) NA Hymenoscyphus, Rhizoscyphus, (Sebacina) Allen et al. 2003, Berch et al. 2003,  Bougoure & Cairney 2005, Selosse et al. 2007