Fern presentation

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Fern presentation

  1. 1. Ecological significance of mycorrhizae in ferns <ul><li>Overview of Mycorrhizae </li></ul><ul><li>My “Predicted patterns” </li></ul><ul><li>G.T.S Baylis' theory of root morphology (1976) </li></ul><ul><li>Boullard confirms theory applies to pteridophytes (1979) </li></ul><ul><li>Further research supports theory (S. M. Berch, B. Kendrick, 1982) </li></ul><ul><li>Hawaiian contradiction ( J. N. Gemma, et al 1992) </li></ul><ul><li>Cheilanthes lanosa study (Palmieri and Swatzell, 2004) </li></ul><ul><li>Other Significant VAM occurrences in ferns </li></ul>
  2. 2. Overview of Mycorrhizae <ul><li>Two types of associations </li></ul><ul><li>Endomycorrhizal fungi- (Vasicular Arbuscular) mycorrhizal fungi-colonize hosts roots intracellularly </li></ul><ul><li>Ectomycorrhizal- colonize hosts roots extracellularly, form hyphal sheath that surrounds root tip </li></ul><ul><li>All Mycorrhizae are symbiotic, usually mutualistic, sometimes pathogenic </li></ul><ul><li>Focus on VAM in ferns </li></ul>
  3. 3. Vesicular-arbuscular mycorrhizas (VAM) <ul><li>No known sexual state </li></ul><ul><li>Fungal hyphae penetrate root cells and form intricately branched, shrub-like arbuscles within the cells </li></ul><ul><li>Over 200 species described, most can colonize most VAM plant species </li></ul><ul><li>Top picture-”infection” site </li></ul><ul><li>Bottom- arbuscule (nutrient transfer) </li></ul>
  4. 4. How does it work? <ul><li>Fungi release powerful enzymes that dissolve tightly bound minerals like phosphorus, sulfur, iron and all the major and minor nutrients used by plants </li></ul><ul><li>Fungi receive translocated root sugars from the host plant </li></ul><ul><li>Fungi translocates these sugars to surrounding mycelium </li></ul>
  5. 5. Benefits of Mycorrhizal relationships <ul><li>Increase establishment and survival chance by; </li></ul><ul><li>-Increase root uptake potential by ten to several thousand fold </li></ul><ul><li>-Reduce drought stress by storing water during dry periods </li></ul><ul><li>VAM increases plant uptake of Phosphorus, N itrogen Potassium, Magnesium, Copper, Zinc, Calcium, Iron, Cadmium, Nickel, and Uranium </li></ul><ul><li>Possible uses for bioremediation, agriculture, and restoration </li></ul><ul><li>(S. Bray et. Al 2003, Gail W.T. Wilson et. Al, 2001,, Janos, 1980) </li></ul>
  6. 6. Patterns seen in vascular plants <ul><li>Mycorrhizae increased either growth or survival in 24 of 28 species studied. </li></ul><ul><li>No ferns included in study </li></ul><ul><li>Do ferns adhere to this pattern? </li></ul><ul><ul><ul><li>(Janos, 1980) </li></ul></ul></ul>
  7. 7. What I expected to find in Ferns <ul><li>Ferns, being among the oldest vascular plants found today would take advantage of mycorrhizal symbiosis. </li></ul><ul><li>Ferns in extreme habitats would predominantly have symbiosis with fungi </li></ul><ul><li>Dispersal would be more likely to occur in habitats where AMF is present </li></ul>
  8. 8. Baylis Theory of root morphology <ul><li>Theory put forth in 1972, states; </li></ul><ul><li>“ Primitive” fleshy roots lack root hairs and are thus highly colonized by hyphae to maintain uptake ability </li></ul><ul><li>“ Advanced” fine roots less so, already having sufficient nutrient uptake </li></ul><ul><li>Boullard 1979 confirms that Baylis' theory holds true in pteridophytes, stated further that evolution in pteridophytes is accompanied by mycotrophy decline </li></ul><ul><li>(Berch, Kendrich, 1982) </li></ul>
  9. 9. Vesicular-Arbuscular Mycorrhizae of Southern Ontario Ferns and Fern-Allies (Shannon M. Berch and Bryce Kendrick 1982) <ul><li>Three features of VAM sparked the need for study </li></ul><ul><li>1) The mycorrhiza-dependance of certain agriculturally valuable plants under conditions of poor nutrition </li></ul><ul><li>2) The apparant lack of host-specificity of the fungus </li></ul><ul><li>3) The ubiguity of the symbiosis in nature </li></ul><ul><li>This Study </li></ul><ul><li>39 Species from 17 genera from the Southern Ontario flora studied </li></ul>
  10. 10. Vesicular-Arbuscular Mycorrhizae of Southern Ontario Ferns and Fern-Allies (Shannon M. Berch and Bryce Kendrick 1982) <ul><li>Methods </li></ul><ul><li>39 Fern species collected, including 4 Equisetum, and 2 Lycopodium species </li></ul><ul><li>Root segments were placed in 50% formalin-acetic acid-alcohol (FAA) for >3 months </li></ul><ul><li>Washed and heated in 10% KOH for >2h </li></ul><ul><li>Second wash, roots teased apart to isolate “fine” roots </li></ul><ul><li>These fine roots were cut into 5-mm long segments </li></ul><ul><li>100 segments per plant were stained and searched for arbuscule presence </li></ul>
  11. 11. Results <ul><li>Ferns on bare rock and crevices showed no VAM </li></ul><ul><li>Most fern species showed VAM associations to some extent </li></ul><ul><li>Infestation varied drastically in several species, see Onoclea sensibilis, from 0%-80% infection </li></ul><ul><li>Root hairs and Mycorrhizae clusters and patterns varied significantly from plant to plant </li></ul><ul><li>State that results support Baylis' and Boullard's theory due to ophioglossales findings </li></ul><ul><li>(Berch, Kendrich, 1982) </li></ul>
  12. 12. Interpretation <ul><li>Pattern of epilithic ferns lacking mycorrhizae most likely due to lack of microorganism competition for nutrients </li></ul><ul><li>Findings “support” Baylis theory of root development, although these findings were mostly in Ophioglossales </li></ul><ul><li>Plants vary in the presence of VAM, pattern of infection and abundance </li></ul>
  13. 13. Questions <ul><li>Does root hair presence affect infection of roots? </li></ul><ul><li>Does infection of roots prevent root hair development? </li></ul><ul><li>No studies found testing this correlation </li></ul>
  14. 14. Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance J. N. Gemma, R. E. Koske and T. Flynn (1992) <ul><li>The unique flora of Hawaii offered an opportunity to study a large proportion of the population for the presence of VAM </li></ul><ul><li>VAM presence in ferns largely unknown in Hawaii, Angiosperms largely mycorrhizal </li></ul><ul><li>Do the patterns seen in the US hold true in HI? </li></ul><ul><li>Roots collected over a two year period on several of the Hawaiian islands from varied substrates and habitats from 45% of fern species-(72 native and 17 naturalized) </li></ul>
  15. 15. Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance J. N. Gemma, R. E. Koske and T. Flynn (1992) <ul><li>Methods </li></ul><ul><li>Methods very similar to previous study </li></ul><ul><li>Plant species were identified as either </li></ul><ul><li>M = consistently mycorrhizal </li></ul><ul><li>N = consistently non-mycorrhizal </li></ul><ul><li>M + N = facultative mycorrhizal (presence and absence seen in same species) </li></ul><ul><li>MI (mycorrhizal index) used to quantify intensity of infection </li></ul>
  16. 16. Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance J. N. Gemma, R. E. Koske and T. Flynn (1992) <ul><li>Results </li></ul><ul><li>Higher percentage of epilithic VAM found (86%) </li></ul><ul><li>Higher percentage of epiphytic VAM found (55%) </li></ul><ul><li>These were previously consider rare or absent (Berch and Kenrich 1982) </li></ul><ul><li>Contradiction to Boullard-mycotrophy was found to occur with equal frequency in primitive and advanced ferns </li></ul><ul><li>Fossil records show high percentage of non-mycotrophic ferns, (not current flora) </li></ul>
  17. 17. Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance J. N. Gemma, R. E. Koske and T. Flynn (1992) <ul><li>Interpretation </li></ul><ul><li>Extremely low percentage of Mainland ferns surveyed for VAM as compared to HI (1.5% TO 44.5%) </li></ul><ul><li>Evolutionary correlation put forth by G.T.S. Baylis may be unfounded, more research needed </li></ul><ul><li>As VAM is established, facultative and obligate species flourish </li></ul>
  18. 18. Mycorrhizal Fungi associated with Cheilanthes Lanosa M. Palmieri and L.J. Swatzell (2004) <ul><li>Cheilanthes lanosa- (lip fern) xerophytic fern, grows on dry, exposed rocky outcrops </li></ul><ul><li>Least resistant to desiccation when compared to Selaginella lepidophylla,(Resurrection Plant), and Notholaena sinuatA var. cochisensis, (Waxy Cloak Fern) </li></ul><ul><li>Ability to thrive as successfully as those mentioned unclear </li></ul><ul><li>Spore germination requirements do not vary from their mesic counterparts </li></ul>
  19. 19. How are these ferns thriving in arid conditions? <ul><li>Palmieri and Swatzell hypothesized that survival could depend upon mycorrhizal symbionts </li></ul><ul><li>VAM not previously described for cheilanthoid ferns (Boullard 1979) </li></ul>
  20. 20. Mycorrhizal Fungi associated with Cheilanthes Lanosa M. Palmieri and L.J. Swatzell (2004) <ul><li>13 plants surveyed from 3 sites in Illinois and Missouri </li></ul><ul><li>Methods, once again similar </li></ul><ul><li>Isolated spores from the soil matrix and an attempt was made to try and identify them </li></ul><ul><li>Pictured-cross section of root segment </li></ul>
  21. 21. Results <ul><li>Ferns collected from 3 sites, 1 in Missouri, 2 in Illinois </li></ul><ul><li>All roots found to be associated with VAM </li></ul>
  22. 22. Interpretation <ul><li>VAM may enable Cheilanthes ferns to thrive in areas previously unsuitable </li></ul><ul><li>Results went against pattern put forth by Boullard </li></ul><ul><li>In Polypodiaceae family, one of the more advanced families of ferns </li></ul>
  23. 23. Questions <ul><li>What are the morphological and environmental differences between VAM and non-VAM ferns of extreme habitats? </li></ul><ul><li>What is the driving force behind VAM association? </li></ul>
  24. 24. A Couple of interesting findings <ul><li>(Agely et. Al 2004) found that VAM increase Arsenic uptake by the Chinese Brake Fern </li></ul><ul><li>(K. Turnau et. Al 2004) found that The presence of VAM fungi in both gametophytes and sporophytes of Pallaea viridis resulted in larger leaf area and root length of the sporophyte </li></ul>
  25. 25. Future research <ul><li>What role has VAM played in the dispersal pattern of ferns </li></ul><ul><li>-Has it enabled ferns to live in extreme conditions? </li></ul><ul><li>-Do VAM ferns have an advantage over non-VAM species? </li></ul><ul><li>Does VAM presence or absence impact root hair development? </li></ul><ul><li>Is the pattern seen in Hawaii typical of other island? Mainland? </li></ul>

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