Application of in vitro methods to study carbon uptake and transport by AM fungi |
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Authors: | David D Douds Jr Philip E Pfeffer Yair Shachar-Hill |
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Institution: | (1) USDA-ARS ERRC, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA;(2) Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA |
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Abstract: | Just as multi-compartmented root chambers have advantages over standard plastic pots for the study of nutrient uptake by arbuscular
mycorrhizal AM] fungi in soil, so the split-plate in vitro system has advantages over the standard dual culture system for
the study of the physiology of AM fungi. We used the split-plate culture system of Ri T-DNA transformed Daucus carota L. roots and Glomus intraradices Schenck & Smith, in which only the fungus has access to the distal compartment, to study the ability of germ tubes and extraradical
and intraradical hyphae to take up 13C-labeled substrates. Labeled substrates were added to one side of the plate divider and plates were incubated for 8 weeks
while the fungus proliferated on the side from which the root was excluded. Tissues then were recovered from the plate and
examined via NMR spectroscopy. Results showed that the morphological phases of the fungus differed in their ability to take
up these substrates, most notably that intraradical hyphae take up hexose while extraradical hyphae cannot. In addition, NMR
studies indicated that intraradical hyphae actively synthesized lipids while extraradical hyphae did not. These data show
that eventual axenic culture of AM fungi is more than a matter of finding the proper substrate for growth. Genetic regulation
must be overcome to make extraradical hyphae behave like intraradical hyphae in terms of C uptake and metabolism.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | arbuscular mycorrhiza carbon uptake in vitro culture nuclear magnetic resonance |
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