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A unique mode of parasitism in the conifer coral tree Parasitaxus ustus (Podocarpaceae)

Citation

Field, TS and Brodribb, TJ, A unique mode of parasitism in the conifer coral tree Parasitaxus ustus (Podocarpaceae), Plant, Cell and Environment, 28, (10) pp. 1316-1325. ISSN 0140-7791 (2005) [Refereed Article]

DOI: doi:10.1111/j.1365-3040.2005.01378.x

Abstract

Almost all parasitic plants, including more than 3000 species, are angiosperms. The only suggested gymnosperm exception is the New Caledonian conifer, Parasitaxus ustus, which forms a bizarre graft-like attachment to the roots of another conifer Falcatifolium taxoides. Yet, the degree of resource dependence of Parasitaxus on Falcatifolium has remained speculative. Here we show that Parasitaxus is definitively parasitic, but it displays a physiological habit unlike any known angiosperm parasite. Despite possessing chloroplasts, it was found that the burgundy red shoots of Parasitaxus lack significant photosynthetic electron transport. However unlike non-photosynthetic angiosperm parasites (holoparasites), tissues of Parasitaxus are considerably enriched in 13carbon relative to its host. In line with anatomical observations of fungal hyphae embedded in the parasite/host union, stable carbon isotopic measurements indicate that carbon transport from the host to Parasitaxus most likely involves a fungal partner. Therefore, Parasitaxus parallels fungus-feeding angiosperms (mycoheterotrophs) that steal carbon from soil mycorrhizal fungi. Yet with its tree-like habit, association with fungi residing within the host union, high stomatal conductance, and low water potential, it is demonstrated that Parasitaxus functions unlike any known angiosperm mycoheterotroph or holoparasite. Parasitaxus appears to present a unique physiological chimera of mistletoe-like water relations and fungal-mediated carbon trafficking from the host. © 2005 Blackwell Publishing Ltd.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Environmental Sciences
Author:Brodribb, TJ (Dr Tim Brodribb)
ID Code:38032
Year Published:2005
Web of Science® Times Cited:14
Deposited By:Plant Science
Deposited On:2005-08-01
Last Modified:2007-12-04
Downloads:0

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