fern presentation

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Ecological significance of mycorrhizae in ferns Overview of Mycorrhizae My “Predicted patterns” G.T.S Baylis' theory of root morphology (1976) Boullard confirms theory applies to pteridophytes (1979) Further research supports theory (S. M. Berch, B. Kendrick, 1982) Hawaiian contradiction ( J. N. Gemma, et al 1992) Cheilanthes lanosa study (Palmieri and Swatzell, 2004) Other Significant VAM occurrences in ferns

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Page 1: Fern presentation

Ecological significance of mycorrhizae in ferns

Overview of Mycorrhizae

My “Predicted patterns”

G.T.S Baylis' theory of root morphology (1976)

Boullard confirms theory applies to pteridophytes (1979)

Further research supports theory (S. M. Berch, B. Kendrick, 1982)

Hawaiian contradiction ( J. N. Gemma, et al 1992)

Cheilanthes lanosa study (Palmieri and Swatzell, 2004)

Other Significant VAM occurrences in ferns

Page 2: Fern presentation

Overview of Mycorrhizae

Two types of associations

Endomycorrhizal fungi- (Vasicular Arbuscular) mycorrhizal fungi-colonize hosts roots intracellularly

Ectomycorrhizal- colonize hosts roots extracellularly, form hyphal sheath that surrounds root tip

All Mycorrhizae are symbiotic, usually mutualistic, sometimes pathogenic

Focus on VAM in ferns

Page 3: Fern presentation

Vesicular-arbuscular mycorrhizas (VAM)

No known sexual state

Fungal hyphae penetrate root cells and form intricately branched, shrub-like arbuscles within the cells

Over 200 species described, most can colonize most VAM plant species

Top picture-”infection” site

Bottom- arbuscule (nutrient transfer)

Page 4: Fern presentation

How does it work?

Fungi release powerful enzymes that dissolve tightly bound minerals like phosphorus, sulfur, iron and all the major and minor nutrients used by plants

Fungi receive translocated root sugars from the host plant

Fungi translocates these sugars to surrounding mycelium

Page 5: Fern presentation

Benefits of Mycorrhizal relationships

Increase establishment and survival chance by;

-Increase root uptake potential by ten to several thousand fold

-Reduce drought stress by storing water during dry periods

VAM increases plant uptake of Phosphorus, Nitrogen Potassium, Magnesium, Copper, Zinc, Calcium, Iron, Cadmium, Nickel, and Uranium

Possible uses for bioremediation, agriculture, and restoration

(S. Bray et. Al 2003, Gail W.T. Wilson et. Al, 2001,, Janos, 1980)

Page 6: Fern presentation

Patterns seen in vascular plants

Mycorrhizae increased either growth or survival in 24 of 28 species studied.

No ferns included in study

Do ferns adhere to this pattern?

(Janos, 1980)

Page 7: Fern presentation

What I expected to find in Ferns

Ferns, being among the oldest vascular plants found today would take advantage of mycorrhizal symbiosis.

Ferns in extreme habitats would predominantly have symbiosis with fungi

Dispersal would be more likely to occur in habitats where AMF is present

Page 8: Fern presentation

Baylis Theory of root morphology

Theory put forth in 1972, states;

“Primitive” fleshy roots lack root hairs and are thus highly colonized by hyphae to maintain uptake ability

“Advanced” fine roots less so, already having sufficient nutrient uptake

Boullard 1979 confirms that Baylis' theory holds true in pteridophytes, stated further that evolution in pteridophytes is accompanied by mycotrophy decline

(Berch, Kendrich, 1982)

Page 9: Fern presentation

Vesicular-Arbuscular Mycorrhizae of Southern Ontario Ferns and Fern-Allies(Shannon M. Berch and Bryce Kendrick 1982)

Three features of VAM sparked the need for study

1) The mycorrhiza-dependance of certain agriculturally valuable plants under conditions of poor nutrition

2) The apparant lack of host-specificity of the fungus

3) The ubiguity of the symbiosis in nature

This Study

39 Species from 17 genera from the Southern Ontario flora studied

Page 10: Fern presentation

Vesicular-Arbuscular Mycorrhizae of Southern Ontario Ferns and Fern-Allies(Shannon M. Berch and Bryce Kendrick 1982)

Methods

39 Fern species collected, including 4 Equisetum, and 2 Lycopodium species

Root segments were placed in 50% formalin-acetic acid-alcohol (FAA) for >3 months

Washed and heated in 10% KOH for >2h

Second wash, roots teased apart to isolate “fine” roots

These fine roots were cut into 5-mm long segments

100 segments per plant were stained and searched for arbuscule presence

Page 11: Fern presentation

Results

Ferns on bare rock and crevices showed no VAM

Most fern species showed VAM associations to some extent

Infestation varied drastically in several species, see Onoclea sensibilis, from 0%-80% infection

Root hairs and Mycorrhizae clusters and patterns varied significantly from plant to plant

State that results support Baylis' and Boullard's theory due to ophioglossales findings

(Berch, Kendrich, 1982)

Page 12: Fern presentation

Interpretation

Pattern of epilithic ferns lacking mycorrhizae most likely due to lack of microorganism competition for nutrients

Findings “support” Baylis theory of root development, although these findings were mostly in Ophioglossales

Plants vary in the presence of VAM, pattern of infection and abundance

Page 13: Fern presentation

Questions

Does root hair presence affect infection of roots?

Does infection of roots prevent root hair development?

No studies found testing this correlation

Page 14: Fern presentation

Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance

J. N. Gemma, R. E. Koske and T. Flynn (1992) The unique flora of Hawaii offered an

opportunity to study a large proportion of the population for the presence of VAM

VAM presence in ferns largely unknown in Hawaii, Angiosperms largely mycorrhizal

Do the patterns seen in the US hold true in HI?

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)

Page 15: Fern presentation

Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance

J. N. Gemma, R. E. Koske and T. Flynn (1992)

Methods

Methods very similar to previous study

Plant species were identified as either

M = consistently mycorrhizal

N = consistently non-mycorrhizal

M + N = facultative mycorrhizal (presence and absence seen in same species)

MI (mycorrhizal index) used to quantify intensity of infection

Page 16: Fern presentation

Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance

J. N. Gemma, R. E. Koske and T. Flynn (1992)

Results

Higher percentage of epilithic VAM found (86%)

Higher percentage of epiphytic VAM found (55%)

These were previously consider rare or absent (Berch and Kenrich 1982)

Contradiction to Boullard-mycotrophy was found to occur with equal frequency in primitive and advanced ferns

Fossil records show high percentage of non-mycotrophic ferns, (not current flora)

Page 17: Fern presentation

Mycorrhizae in Hawaiian Pteridophytes: Occurrence and Evolutionary Significance

J. N. Gemma, R. E. Koske and T. Flynn (1992)

Interpretation

Extremely low percentage of Mainland ferns surveyed for VAM as compared to HI (1.5% TO 44.5%)

Evolutionary correlation put forth by G.T.S. Baylis may be unfounded, more research needed

As VAM is established, facultative and obligate species flourish

Page 18: Fern presentation

Mycorrhizal Fungi associated with Cheilanthes LanosaM. Palmieri and L.J. Swatzell (2004)

Cheilanthes lanosa- (lip fern) xerophytic fern, grows on dry, exposed rocky outcrops

Least resistant to desiccation when compared to Selaginella lepidophylla,(Resurrection Plant), and Notholaena sinuatA var. cochisensis, (Waxy Cloak Fern)

Ability to thrive as successfully as those mentioned unclear

Spore germination requirements do not vary from their mesic counterparts

Page 19: Fern presentation

How are these ferns thriving in arid conditions?

Palmieri and Swatzell hypothesized that survival could depend upon mycorrhizal symbionts

VAM not previously described for cheilanthoid ferns (Boullard 1979)

Page 20: Fern presentation

Mycorrhizal Fungi associated with Cheilanthes LanosaM. Palmieri and L.J. Swatzell (2004)

13 plants surveyed from 3 sites in Illinois and Missouri

Methods, once again similar

Isolated spores from the soil matrix and an attempt was made to try and identify them

Pictured-cross section of root segment

Page 21: Fern presentation

Results

Ferns collected from 3 sites, 1 in Missouri, 2 in Illinois

All roots found to be associated with VAM

Page 22: Fern presentation

Interpretation

VAM may enable Cheilanthes ferns to thrive in areas previously unsuitable

Results went against pattern put forth by Boullard

In Polypodiaceae family, one of the more advanced families of ferns

Page 23: Fern presentation

Questions

What are the morphological and environmental differences between VAM and non-VAM ferns of extreme habitats?

What is the driving force behind VAM association?

Page 24: Fern presentation

A Couple of interesting findings

(Agely et. Al 2004) found that VAM increase Arsenic uptake by the Chinese Brake Fern

(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

Page 25: Fern presentation

Future research

What role has VAM played in the dispersal pattern of ferns

-Has it enabled ferns to live in extreme conditions?

-Do VAM ferns have an advantage over non-VAM species?

Does VAM presence or absence impact root hair development?

Is the pattern seen in Hawaii typical of other island? Mainland?