mycorrhiza types, distribution and significance.

With reference to agriculture.

1. MYCORRHIZA TYPES, DISTRIBUTION, AND SIGNIFICANCE WITH REFERENCE TO AGRICULTURE . PRESENTED BY SHABNOOR SHAIKH MSC 1

2. OVERVIEW OF MYCORRHIZA Mycorrhiza was first used by G erman researcher A.B . Frank in 1885. It’s greek word viz mycos - fungus and rhiza -root. Symbiotic mutualistic relationship with bidirectional nutrient exchange. About 90% of all land plants are associated with it except Cruciferae, Chenopodiaceae and Resedaceae .

3. THREE WAY INTERACTION. Mycorrhizal association involves 3 way interaction between Host, Fungi and Soil.

4. TYPES OF ASSOCIATION Mycorrhiza are commonly divided into endomycorrhiza and ectomycorrhiza . These two type are differentiated by- Ectomycorrhiza do not penetrate individual cells within the root. Endomycorrhiza penetrate the cell wall and invaginate the cell membrane.

5. ENDOMYCORRHIZA Endomycorrhiza’s are variable belonging to basidiomycetes and associated with root development which have been further classified as :- Vesicular arbuscular mycorrhizae (VAM). Ericoid mycorrhizae . Arbutoid mycorrhizae . Monotropoid mycorrhizae . Orchid mycorrhizae .

6. VESICULAR ARBUSCULAR MYCORRHIZA VAM are produced by aseptate mycelial fungi which penetrate root forming v esicles and arbuscles . Vesicles are thin or thick walled structure which stores polyphosphate and other minerals. Arbuscles are dichotomously branched haustoria which lives for 4 days and then get lysed releasing stored food as oil droplets in the cortex.

7. ERICOID MYCORRHIZA Slow growing, septate and mostly sterile . Rootlets are covered by very loose, sparse, dark hyphae that penetrates the cortex forming intercellular coils. These coils degenerate after 3-4 weeks like VAM. They usually improve the uptake of P and N nutrition of plants.

8. MONOTROPOID MYCORRHIZA 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. Boletus a mycorrhizal fungus asso­ciated with roots of both pine and Monotropa . Fungal sheath present.

9. ORCHID MYCORRHIZA All orchids are myco -heterotrophic at some stage and form orchid mycorrhizas with a range of basidiomycete fungi. Their hyphae penetrate into the root cells and form pelotons (coils) for nutrient exchange The fungus provides C-nutrition to the seeds.

10. ECTENDOMYCORRHIZA (ARBUTOID) They have mycorrhiza intermediate in form between ecto and endomycorrhiza types found in ericaceae . The root system is differentiated in short and long roots. Short roots are swollen and covered by mantle. The former actually penetrate the cortical cells and fill them with coils.

11. ECTOMYCORRHIZA These are association , where fungi form a mantle around roots with no hyphal penetration in the cells. Fungal hypha is generally separate. Hartig’s net is present between the cells which is 40µm thick. Most conspicuous and easily recognized.

12. DISTRIBUTION OR OCCURRENCE OF ENDOMYCORRHIZA Ubiquitous in Artic, Temperate and Tropical regions found in almost all angiosperms including gymnosperms and liverworts. Distribution pattern were surveyed in montane scrub grassland, alpine steppe ad alpine meadow. Their altitudes are ranging from 3500 to 5200m on Tibetan plateau. Their general occurrence is in Gramineae , Palmae , Rosaceae , Leguminosae and Papilionaceae . They are reported from carboniferous and Devonian periods.

13. DISTRIBUTION OR OCCURRENCE OF ECTOMYCORRHIZA Found in 3% of seeded plants viz common in northern temperate forest especially in Fagaceae and Pinaceae where as in tropics Myrtacceae and Dipterocarpacae . Majority comes from the 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.

14. SIGNIFICANCE WITH REFERENCE TO AGRICULTURE Increases nutrient uptake of plant from soil. Increase diversity of plants. Produce uniform seedling. Significant role in nutrient recycling. More tolerant to adverse soil chemical constraints which limit crop production. Inoculation of VAM as biofertiliser pro­vides a distinct possibility for the uptake of P in phosphorus-deficient soil.

15. Increases plant resistance to diseases and drought. Improve soil structure. Protection of plants during stress condition. Uptake of sulphur and inorganic salts from soil. Obligatory for the germination of orchid seeds.

16. CONCLUSION 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 from soil. AM fungi useful in agriculture because it serves as biofertilizers as it helps in the absorption of phosphorus and other nutrient uptake.

17. REFERENCE Introduction to mycology by R.S Mehrotra and R.K Aneja . Principles of microbiology.