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Abstract Detail


The Greatest Opportunists of all: Celebrating 40 years of Job Kuijts

Cameron, Duncan D [1].

All that glitters is not gold and all thats green does not photosynthesise: The chlorophyll containing orchid Corallorhiza trifida derives little carbon through photosynthesis.

While measurements of tissue stable isotope signatures and isotope mixing models have suggested that the green orchid Corallorhiza trifida is photosynthetically active and hence only partially myco-heterotrophic, these assumptions have not been validated by direct analysis of carbon assimilation.
The photosynthetic capabilities of three orchid species assumed on the basis of the indirect methods or chlorophyll content to have differing trophic strategies: Neottia nidus-avis (fully myco-heterotrophic), Cephalanthera damasonium (partially autotrophic), Corallorhiza (partially autotrophic), as well as saplings of an autotrophic tree, Fagus sylvatica, were investigated by combining the determination of chlorophyll content and fluorescence parameters with direct measurement of the potential for CO2 assimilation using 13C isotope tracers in the field.
Chlorophyll content and fluorescence values were indicative of ineffective photochemical processes in Neottia and reduced efficiency of photochemical processes in Corallorhiza. These differences are reflected in the mean assimilation rates of 13CO2 of 594±129, 331±72, 12.4±2.4 and 7.3±0.9 mg g-1 h-1 for Fagus, Cephalanthera, Corallorhiza and Neottia respectively.
Our study, while confirming the fully myco-heterotrophic status of Neottia and the partially autotrophic condition in Cephalanthera, also demonstrates under field conditions that Corallorhiza is physiologically closer to the fully myco-heterotrophic condition than has previously been recognized.


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1 - University of Sheffield, Department of Animal and Plant Sciences, Alfred Denny Building, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK

Keywords:
myco-heterotrophy
Epiparasite
Orchid mycorrhiza
stable isotope.

Presentation Type: Symposium or Colloquium Presentation
Session: SY11
Location: Cottonwood A/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 4:15 PM
Number: SY11009
Abstract ID:22


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