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1	Fixation, Partitioning and Export of Carbon in two Species of the Plantaginaceae Szucs, Ildiko 05 April 2013 (has links) During photosynthesis Plantaginaceae species can produce glucose derivatives such as iridoid glycosides and alcohol sugars that in addition to sucrose can be exported from leaves. Plantago lanceolata transported sorbitol in addition to sucrose especially at warmer leaf temperatures. However, two iridoids, catalpol and aucubin, found in P. lanceolata were not readily labelled from 14CO2 under any conditions examined. In contrast, in two greenhouse, cut-flower cultivars of Antirrhinum majus the iridoids, antirrhinoside and antirrhide, were readily 14C-labelled along with sucrose but little 14C was recovered in alcohol sugars (e.g., mannitol). The amount of 14C-partitioned into antirrhinoside increased at higher temperatures. Exposing leaves of P. lanceolata and A. majus to reduced-photorespiratory conditions (e.g. short-term CO2 enrichment and/or low O2) increased fixation and export. Under low O2 in P. lanceolata sorbitol 14C-labelling increased relative to sucrose and in A. majus 14C-labelling of sucrose increased relative to antirrhinoside. Also 14C-labelling of antirrhide increased more than antirrhinoside. During both short-term and long-term acclimation to high CO2, whole plant NCER, leaf photosynthesis and export increased in A. majus. Taken together the temperature and CO2 enrichment studies show plasticity in Plantaginaceae species to synthesize and transport sucrose and auxiliary glucose esters and alcohol sugars in a species-specific manner (depending on the rate of carboxylation). Iridoid glycoside terpenoid terpene monoterpene Antirrhinum majus Plantago lanceolata Plantaginaceae whole plant photosynthesis reduced photorespiratory low O2 elevated CO2 CO2 14CO2 14C-labelling 14C-partitioning temperature alcohol sugar sorbitol mannitol snapdragon aucubin catalpol antirrhide antirrhinoside leaf long term short term export phloem partitioning glucose derivative gas exchange

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Fixation, Partitioning and Export of Carbon in two Species of the Plantaginaceae