The document defines different types of mycorrhizal associations between fungi and plant roots that provide benefits to both organisms. It describes arbuscular mycorrhizas formed by Glomeromycota fungi in plant roots, which usually have structures called arbuscules and vesicles. It also discusses ectomycorrhizal associations with a Hartig net between root cells and a fungal mantle on root surfaces. The document provides examples of orchid mycorrhizas with fungal coils inside thin root cells, and ericoid mycorrhizas in the plant family Ericaceae with fungal coils or hyphae in root cells.

1. Zohaib ul Hassan BAGF11E073
Plant Pathology 8th
zuhaib1144@gmail.com
University College of Agriculture,
University of Sargodha, Punjab,
Pakistan

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

3.  “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 are a subset of
symbioses where two or more different living
organisms receive mutual benefits.

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

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

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

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

13. Arbuscule of a Glomus species in a
root cortex cell.

14. Cortical Hartig net of Pinus ECM root.

15. 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 alli
ance: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