Cypripedium candidum and negative effects of mycorrhizae

Discussion in 'Orchid Conservation' started by naoki, Feb 29, 2016.

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  1. Feb 29, 2016 #1

    naoki

    naoki

    naoki

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    This is a bit technical, so most people probably don't care. But I thought that it could be interesting for some people interested in biology of Cypripedium.

    Here is an interesting MS thesis:
    https://www.researchgate.net/profil...osynthesis/links/53e21f730cf24f90ff65bbef.pdf

    I haven't read it in detail (so I might be wrong in details), but it shows unexpected results. In more fertile sites, the roots are more infected by mycorrhizae. The fungi can help water acquisition, so C. candidum can do more photosynthesis. However, the plants don't get the benefit (fungi seem to steal it), and more fungi seems to influence the performance of plant negatively. In other words, Cyps in the nutrient poor site do better because they don't get infected by mycorrhizae.

    The relationships between orchids and mycorrhizae are crazier and crazier as I learn more about it. I used to think that orchids seem to have an upper-hand over fungi on this "synergistic" relationship, but not in this case.

    Here is the summary version (it is not so clear about the message, though)
    http://my.chicagobotanic.org/science_conservation/making-a-splash-with-orchids/
     
  2. Feb 29, 2016 #2

    JAB

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    Naoki
    Great find! I never would imagine mycorrhizae would be detrimental the orchid (or anything for that matter). I assumed they always worked in conjunction with each other.
    Is this a possible explanation for why so many flaskings of species fail?? The wrong type/amount of myco in the agar??

    Thanks for sharing brother,
    Jake
     
  3. Feb 29, 2016 #3

    eggshells

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    There is no mycorrhizae or any type of fungi in In-vitro.
     
  4. Feb 29, 2016 #4

    Ray

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    Let us also member that "mycorrhizae" is a VERY broad term. I imagine the species of fungus is a factor as well.
     
  5. Feb 29, 2016 #5

    PaphMadMan

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    I haven't looked at this yet, but I don't find it surprising that the balance of the symbiosis varies in different environments. Even if the fungus becomes a net taker in a rich environment, if the Cyp wouldn't establish and compete there without it that is a huge benefit. The relationship evolved as a mutual benefit for both organisms but that doesn't mean it is ever balanced, and certainly not purely a gift to the Cyp. Characterizing the symbiosis under different conditions is interesting anyway.

    And a note on terminology: mycorrhiza (plural mycorrhizae) is the association between plant roots and fungus, not the fungus itself.
     
  6. Feb 29, 2016 #6

    Ray

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    True enough, but I suspect that the fungal partner in that association will make a huge difference in the results.
     
  7. Feb 29, 2016 #7

    naoki

    naoki

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    Jake, recent trend (understanding) is that mutualism between orchids and fungi is context-dependent. If environment changes, mutualism goes to commensalism or parasitism.

    Also, eggshell is right, most of the epiphytic orchids use asymbiotic seed germination, so there is no fungi involved. People do use symbiotic flasking with terrestrials, though.

    I agree, the interesting part is who is going to choose the partner; fungi or host.

    I think the surprising part is that the trend was the opposite of what we expected. In a nutrient rich environment, plant should choose NOT to associate with fungi. In other words, if carbon is the limiter (and not mineral nutrients or water), plants don't get benefit from fungi (and fungi become the parasite). In many cases, plants seem to be able to control. So if you fertilize orchids with lots of phosphate, plants get rid of the association with the fungi in the pot. In the nutrient poor environment, plants could use the help from fungi, so they want to maintain the relationship. But I was surprised that more fungi observed in nutrient rich environment (and plants can't get rid of them). But I guess you have a point. In the rich soil, there might be other factors (e.g. disease resistance) which allow them to establish via mycorrhizae.

    Good point, I wasn't sticking with the correct terminology!
     
  8. Mar 6, 2016 #8

    dodidoki

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    You said: " In other words, Cyps in the nutrient poor site do better because they don't get infected by mycorrhizae."

    Do you mean that cyps are going better in inorganic mix in culture, too?
     
  9. Mar 6, 2016 #9

    cnycharles

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    In nature they seem to grow in very wet calcareous (marl) areas that may limit some mychorrizae.


    Elmer Nj
     
  10. Mar 6, 2016 #10

    naoki

    naoki

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    I still haven't had time to read the thesis in detail. But going from the abstract, I think that your interpretation might be a stretch. In these particular field sites, the fungi seems to be more parasitic than symbiotic. The fungi in the pots are likely to be different from what they observed in the field. So I wouldn't generalize the results to the pot culture.

    Aside from this study, people generally thought that plants are more likely to make mycorrhizal association under the nutrient (or water) limited environment. More specifically, high phosphate fertilization generally removes the fungal associates. MSU and K-Lite has low P, so they might be good in this aspect (if mycorrhizae help plants).

    In some studies, mycorrhizal fungi are isolated from Paphs cultured in pots. I'm not sure how much it will contribute to Cyp culture, though (since most of us uses mostly inorganic media). I've been including cardboard strips to Cyp pots in the last year (hoping for some fungal associates).
     
  11. Mar 11, 2016 #11

    KyushuCalanthe

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    Thanks for the link Naoki, interesting findings. I remember reading an article in a NANOA journal back in the late 90's or early 2000's about C. acaule in coastal Virginia. In that population the plants were clustered around oak roots that were near the surface of the ground, apparently because the fungal symbiont was attached to the tree's roots. In the same article they discussed the relationship between the fungus and the Cyp, however I don't remember clearly the details, but under unfavorable conditions, the fungus overwhelms the orchids and kills the plant.

    The point is that the relationship between microflora in the soil and orchid roots is a serious balance thing. So the question is, what are you trying to grow, the fungus or the orchid? All the growers of Cypripediums I know of choose the latter. I'm sure an effort can be made to grow both the orchid and the fungus together, but somehow the correct balance point must be maintained or trouble with follow. In propagating these plants most folks use a regimen of inorganic fertilizers and fungicides, both of which will seriously impact microflora populations.
     

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