Fungi Symbiosis

Fungal Symbiosis :Two common mutualistic relationships involving fungi are mycorrhiza and lichen

1. Fungal Symbiosis

2. Symbiosis Sym=together Biosis =life Symbionts : the organisms involved Commensalism: one symbiont receives benefit Parasitim : one called a parasite, benefits at the expense of the other Mutualism : which is beneficial to both organisms involved.

3. “the intimate association between two distantly , related species that are mutually benefiting from this association.” Definition in the biological sense is broader and was first defined in this sense by Anton deBary 1879

4. M ainly two Lichens Mycorrhiza

5. L ichens

6. Fungus + Algae An association between a fungus and an alga that develops into a unique morphological form that is distinct from either partner is termed a lichen . fungus Algae mycobiont phycobiont The algal partner possess the green pigment chlorophyll Performs photosynthesis The fungus, protects its partners

7. M ycobionts Mycobionts , in the traditional sense of lichens, belong in the phylum Ascomycota . mycobiont + photobiont fugus seen to be composed of filamentous cells and each such filament is called a hypha . These hyphae grow by extension and may branch but keep a constant diameter.

8. P hycobionts either green algae or cyanobacteria fungus benefits from the algae or cyanobacteria because they produce food by photosynthesis

9. Upper cortex Algal layer Medulla Lower cortex

10. T ypes

11. C rustose These lichens form a crust on rocks or in tiny spaces between rock crystals . Their bright colors—red, orange, yellow—prevent damage from too much sunlight . Slow-growing and longlived , some crustose lichens take 25 years to grow 1 inch. Some found in glaciers are several thousand years old.

12. F oliose lichen These leafy-looking lichens have root like threads anchor them to tree,trunks , rocks, and soil .

13. F ruticose These bushy lichens often look like miniature shrubs or trees ( Usnea cavernosa )

14. Rugged Pioneers Clean-Air Lovers

15. Many Uses To dye fabric—such as yarn to weave rugs Brew medicinal teas To make poultices to soothe skin irritations Certain species of lichens contain a blue coloring matter called litmus

16. M ycorrhizae

17. What is mycorrhiza ? Mycorrhiza (plural, - ae or –as) - Greek - means “fungus+ root” A symbiotic association between a plant and nonpathogenic fungus that colonizes the cortical tissue of roots during periods of active plant growth. These symbioses are characterized by movement of nutrients - carbon flows to the fungus and inorganic nutrients move to the plant, thereby providing a critical linkage between the plant root and soil. Few higher plants do not form mycorrhizal associations, 10-20% including some aquatic vascular plants and members of the Brassicaceae , Cyperaceae , and Juncaceae

18. Characteristics of Mycorrhizae Enhances mineral transport to plants,especially phosphorous. Infection occurs only at root tips. Relationships obligate and facultative. Plants with mycorrhizae more drought resistant. Plants with mycorrhizae more resistant to plant pathogens .

19. Characteristics ofMycorrhizae Occurs in almost all plants. Some exceptions are Crucifers and aquatic plants. It is thought that plants would nevernhave made the transition to the terrestrial environment without mycorrhizal fungus

20. Categories of Mycorrhizae Two Major:- Ectomycorrhizae : Mycelium forms an external sheath around root tip. Does not penetrate cells of root. Endomycorrhizae : Mycelium does not form sheath and does penetrate root cells.

21. Mycorrhizae inoculum Mycorrhizal inoculum is material that carries mycorrhizal fungi in a usable form to the intended host plants. In the case of VAM fungi, inoculum may be spores, hyphae , and colonized root fragments. The quality of mycorrhizal inoculum is not easy to assess, but the best way is an expression of the number of propagules per unit volume of material. Propagules include spores, hyphae , and root fragments.

22. Functions of Mycorrhizal Fungus uses organic nutrients (including sugars) produced by plant ECM are not obligate mutualists but VAM are. Fungi impart benefits to plant by increasing: nutrient absorption, especially phosphorus, water uptake, tolerance of harsh environmental conditions, including polluted environments (e.g. acts as shield against acidity, elemental toxicity and pathogens).

23. Benefits of Mycorrhizae Increased uptake of nutrients Hyphae explore the soil for nutrients, increase surface area for nutrient absorption transport them back to the plant . The nutrients P, Zn, C, N, Cu and S have been shown to be absorbed and translocated to the host by mycorrhizal fungi Increased rootlet size and longevity Mycorrhizal plants have larger roots than nonmycorrhizal plants regardless of whether mycorrhizal fungi are present.