title: Effects of high CO2 on growth and metabolism of Arabidopsis seedlings during growth with a constantly limited supply of nitrogen.
abstract: Elevated CO2 has been reported to stimulate plant growth under nitrogen-sufficient conditions, but the effects of CO2 on growth in a constantly nitrogen-limited state, which is relevant to most natural habitats of plants, remain unclear. Here, we maintained Arabidopsis seedlings under such conditions by growing a mutant with reduced nitrate uptake activity on a medium containing nitrate as the sole nitrogen source. Under nitrogen-sufficient conditions (i.e. in the presence of ammonium), growth of shoots and roots of both the wild type (WT) and the mutant was increased approximately 2-fold by elevated CO2. Growth stimulation of shoots and roots by elevated CO2 was observed in the WT growing with nitrate as the sole nitrogen source, but in the mutant grown with nitrate, the high-CO2 conditions stimulated only the growth of roots. In the mutant, elevated CO2 caused well-known symptoms of nitrogen-starved plants, including decreased shoot/root ratio, reduced nitrate content and accumulation of anthocyanin, but also had an increased Chl content in the shoot, which was contradictory to the known effect of nitrogen depletion. A high-CO2-responsive change specific to the mutant was not observed in the levels of the major metabolites, although CO2 responses were observed in the WT and the mutant. These results indicated that elevated CO2 causes nitrogen limitation in the seedlings grown with a constantly limited supply of nitrogen, but the Chl content and the root biomass of the plant increase to enhance the activities of both photosynthesis and nitrogen uptake, while maintaining normal metabolism and response to high CO2.
authors: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
authors: Nobuyuki
authors: N
authors: Takatani
authors: Takuro
authors: T
authors: Ito
authors: Takatoshi
authors: T
authors: Kiba
authors: Marie
authors: M
authors: Mori
authors: Tetsuro
authors: T
authors: Miyamoto
authors: Shin-Ichi
authors: S
authors: Maeda
authors: Tatsuo
authors: T
authors: Omata
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology*; D002734:Chlorophyll / Q000378:metabolism; D055786:Gene Knockout Techniques; D055442:Metabolome; D009154:Mutation; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000172:deficiency* / Q000378:metabolism; D010788:Photosynthesis; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D012987:Soil
chemical_list: D064751:Ammonium Compounds; D000872:Anthocyanins; D009566:Nitrates; D012987:Soil; D002734:Chlorophyll; D002245:Carbon Dioxide; D009584:Nitrogen
keywords: Arabidopsis; High-CO2 response; Metabolome; Nitrogen limitation