MYCORRHIZA TYPES, DISTRIBUTION, AND SIGNIFICANCE
WITHREFERENCE TO AGRICULTURE.
Mycorrhiza was first used by German researcher A.B. Frank in 1885.
It’s greek word viz mycos- fungus and
Symbiotic mutualisticrelationshipwithbidirectional nutrient
About 90%of all land plants are associated with it except
Cruciferae, Chenopodiaceae and Resedaceae.
THREE WAY INTERACTION.
Mycorrhizal associationinvolves 3 way interactionbetween Host,
Fungi and Soil.
TYPES OF ASSOCIATION
Mycorrhiza are commonly dividedinto endomycorrhiza and
These two type are differentiated by-
Ectomycorrhiza do not penetrate individual cells withinthe root.
Endomycorrhiza penetrate the cell wall and invaginate the cell
Endomycorrhiza’sare variable belonging to basidiomycetesand associated
with root development which have been furtherclassifiedas :-
Vesiculararbuscular mycorrhizae (VAM).
VAMare produced by aseptate mycelial fungi whichpenetrateroot forming
vesicles and arbuscles.
Vesicles are thin or thick walled structure which stores polyphosphateand
Arbuscles are dichotomously branched haustoria which lives for 4 days and
then get lysed releasing storedfoodas oil droplets in the cortex.
Slowgrowing, septate and mostly sterile .
Rootlets are coveredby very loose, sparse, dark hyphae that penetrates the cortex
forming intercellular coils.
Thesecoils degenerate after 3-4 weeks likeVAM.
They usually improve the uptake of P and N nutritionof plants.
Seen in Monotropaceae which are achlorophyllous.
Uses their mycorrhizae not only to obtain minerals and nutrients, but also to
tap the carbon supplies via the nearby plants or soil by breakdown of
cellulose and lignin.
Boletusa mycorrhizal fungus associatedwithroots of both pine and
Fungal sheath present.
All orchids are myco-heterotrophic at some stage and formorchid
mycorrhizas with a range of basidiomycete fungi.
Their hyphae penetrate into the root cells and formpelotons (coils) for
The fungus provides C-nutrition to the seeds.
They have mycorrhiza intermediate in formbetween ecto and endomycorrhiza
types found in ericaceae.
The root systemis differentiated in short and long roots.
Short roots are swollen and covered by mantle.
The formeractually penetrate the cortical cells and fill themwithcoils.
Theseare association, where fungi forma mantlearound roots withno hyphal penetration
in the cells.
Fungal hypha is generally separate.
Hartig’s net is present between
the cells whichis 40µmthick.
Most conspicuous and easily
Ubiquitous in Artic, Temperateand Tropical regionsfound in almost all
angiospermsincludinggymnosperms and liverworts.
Distribution pattern weresurveyed in montane scrubgrassland, alpine
steppe ad alpine meadow.
Their altitudes are rangingfrom3500 to 5200mon Tibetan plateau.
Their general occurrence is in Gramineae, Palmae, Rosaceae, Leguminosae
They are reported fromcarboniferousand Devonian periods.
DISTRIBUTION OR OCCURRENCE
Found in 3% of seeded plantsviz common in northern temperate forest
especially in Fagaceae and Pinaceae where as in tropics Myrtacceae and
Majoritycomes fromthe general Amanita, Boletus and Tricholoma.
Its distribution is limited to the arid areas of south-central Asia and the
northern hilly margin of the Tibetan Plateau.
SIGNIFICANCE WITHREFERENCE TO
Increases nutrient uptake of plant fromsoil.
Increase diversity of plants.
Significant role in nutrient recycling.
More tolerant to adverse soil chemical constraints which limit crop
Inoculation of VAM as biofertiliser provides a distinct possibility for the
uptake of P in phosphorus-deficient soil.
Increases plant resistance to diseases and drought.
Improve soil structure.
Protection of plants during stress condition.
Uptake of sulphur and inorganic salts fromsoil.
Obligatory for the germination of orchidseeds.
Mycorrhizal association is very essential for the plants because it has
several benefits like absorption of nutrients, increase drought
resistance, enhance plant efficiency in absorbing water and nutrients
AM fungi useful in agriculture because it serves as biofertilizers as it
helps in the absorption of phosphorus and other nutrient uptake.
Introduction to mycology by R.S Mehrotra and R.K Aneja.
Principles of microbiology.