Mycorrhizal association

1. Mycorrhizal Association Tara H. Shkur 2012

2. The fungus-root symbiotic relationship is called “ Mycorrhizae ”

3. Mycorrhizae The most prevalent beneficial organisms associated with plants, however, are soil-inhabiting fungi that form mutualistic root–fungal associations referred to as mycorrhizas All mycorrhizas have intimate contact between hyphae and plant cells in an interface where nutrient exchange occurs . Majority of plants form mycorrhizas , it is likely to lie somewhere between 80% and 90%. In many of these associations between 10% and 30% of the food produced by the plant moves through to the fungi.

4. Mycorrhizae Mycorrhizas are found in a wide range of habitats, including deserts, lowland tropical rainforests, high latitudes and altitudes Uptake of nutrient and Mineral nutrient acquisition from soil is considered to be the primary function of mycorrhizas , in addition to it’s roles in ecology, and man economic uses..

5. The pioneering work of Frank , resulted in the recognition of two broad subdivisions of mycorrhizas , E ctomycorrhizas and Endomycorrhizas

6. Mycorrhizae Types Two major types of mycorrhiza occur in Nature E ndomycorrhiza “ vesicullar-arbuscular ” ( common in more than 80 % of terrestrial plant species) E ctomycorrhiza (specific to conifers and some broadleaved woody species ) %15 of plants There exists other types: Ericoid, Orchid, monotropoid mycorrhiza of less ecological importance.

7. Ectomycorrhiza The formation of a mantle or sheath of hyphae that covers considerable portions of lateral roots, the development of hyphae between root cells form a complex highly branched structure called the Hartig net, Ectomycorrhiza : root tip of Pinus nigra colonised by ectomycorrhizal fungus

8. Ectomycorrhizas are usually found on tree species although a few shrub and herbaceous species may also develop this association. A detailed list of the conifer and angiosperm families . *Fungi groups with large fruiting bodies, e.g. mushrooms, truffles and puffballs. Ectomycorrhiza

9. Ectomycorrhizas can also confer pathogen resistance to their plant partner, and they are more effective at this, compared to AM roots

10. It has been estimated that between 5,000 and 6,000 species of fungi form ecto - or ectendo-mycorrhizas . Around 4,500 of these are epigeous (have above-ground fruiting bodies), but up a quarter are hypogeous (with underground fruiting bodies) such as truffles White Truffles ( Tuber magnatum ). Fly agaric ( Amanita muscaria ).

11. Endomycorrhiza They are either Vesicular or Arbuscular ; Consists of hyphae that meander between the cortex cells, and often enter them. Vesicular- arbuscular mycorrhiza : Highly colonized root of maize dyed with trypan blue. Mycorrhizal formations are clearly visible: 1) vesicles; 2) arbuscules

12. Main cellular features of the arbuscular endomycorrhiza Hyphae from a germinating spore infect a root hair and can grow within the root between root cortical cells and also penetrate individual cells, forming arbuscules . These are finely branched clusters of hyphae, which are thought to be the major site of nutrient exchange between fungus and plant.

13. Fully developed arbuscule of Glomus mosseae in cortical cell

14. • Arbuscules : transfer organs of the mycorrhizae . •Hyphae : connect root to soil . Act as pipeline •Spores : resting, lipid filled structures. Is the seed of the fungus world. •Identification is based on these .

15. Many common desert plants, including cacti, are heavily mycorrhizal .. indicating that mycorrhizas have a particularly important role in water relations in dry ecosystems and in soils with poor water retention

16. Reasons, why the study of mycorrhizas is important ? Mycorrhizas increase nutrient uptake from the soil . Mycorrhizal fungi can be used in the biocontrol of pathogenic fungi and nematodes . Some mycorrhizal fungi can bind heavy metals thus protecting plants from toxic levels of these substances . Mycorrhizas have a positive effect on the establishment of plant communities.

17. If no other factors are limiting, growth will be proportional to the amount of P absorbed by plants . Mycorrhizae may supply up to 80%* of the plant P.

18. Agricultural advantages • Allow plants to draw more nutrients and water from the soil, including phosphorus • Result in vigorous and healthy plants • Accelerate rooting • Increase plant survival • Increase drought tolerance and others stresses • Enhance flowering and fruiting

19. Ecological Importance Improvement of soil structure • Stimulation of beneficial microbial activity Water infiltration improvement • Reduction of erosion and nutrient leaching

20. AM ; also contribute to microaggregate formation in soils due to the production of a glycoprotein called “ glomalin ”; glycoprotein that acts as a glue for soil structure . Aggregate formation reduces decomposition of SOM, maintaining C in the soil. SOM also holds water and retains nutrients.

21. Reference: Books: - Mycorrhiza anatomy and cell biology - Mycorrhiza symbiosis 2 nd edition Websites: -http:// mycorrhizas.info/index.html -http:// en.wikipedia.org/wiki/ Mycorrhiza -http://www.mycorrhizae.com/ -http :// www.world-of- fungi.org/Assets/ Mostly_Mycology / Diane_Howarth /mycorrhizal%20types.htm

22. Thanks for your attention