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Abstract Detail


Green, Walton [1].

Plants with Lungs: the Function of Aerenchyma in the Arborescent Lycopsids.

Most species of the modern family Isoëtaceae (Quillworts), and some other modern hydrophytes, utilize a metabolic pathway for carbon fixation that involves uptake of sedimentary carbon and enrichment of CO2 in internal gas spaces as a carbon-concentrating mechanism. This metabolism, which is related to 'aquatic CAM', is characterized by morphological, physiological, and biochemical adaptations for decreasing photorespirative loss, aerating roots, and maintaining high growth rates in anoxic, oligotrophic, stressed environments. Some of the closest relatives of the Isoëtaceae were the 'arborescent lycopsids', which were among the dominant organisms found in lowland coal-swamp ecosystems during the Carboniferous and Permian periods (c. 300 Ma). Morphological, ecological and geochemical evidence supports the hypothesis that the arborescent lycopsids shared this unusual metabolism with living Isoëtaceae and processed a biogeochemically significant proportion of organically fixed carbon over a period of about 100 million years in the late Paleozoic. The temporal coincidence between the dominance of plants with this metabolism and an aberrant global atmosphere (high O2; low CO2) suggests that it should not be considered merely a variant of CAM photosynthesis, but an adaptive, metabolic strategy of potential importance to global biogeochemical systems.

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1 - National Museum of Natural History, Smithsonian Institution, Department of Paleobiology, Mrc 121, Washington D.C., 20560, USA

aquatic CAM
arborescent lycopsids
metabolic pathway

Presentation Type: Oral Paper:Papers for Topics
Session: 41
Location: 551B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 2:30 PM
Number: 41005
Abstract ID:531

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