title: Nitrogen assimilation and growth of wheat under elevated carbon dioxide.
abstract: Simultaneous measurements of CO(2) and O(2) fluxes from wheat (Triticum aestivum) shoots indicated that short-term exposures to elevated CO(2) concentrations diverted photosynthetic reductant from NO(3)(-) or NO(2)(-) reduction to CO(2) fixation. With longer exposures to elevated CO(2), wheat leaves showed a diminished capacity for NO(3)(-) photoassimilation at any CO(2) concentration. Moreover, high bicarbonate levels impeded NO(2)(-) translocation into chloroplasts isolated from wheat or pea leaves. These results support the hypothesis that elevated CO(2) inhibits NO(3)(-) photoassimilation. Accordingly, when wheat plants received NO(3)(-) rather than NH(4)(+) as a nitrogen source, CO(2) enhancement of shoot growth halved and CO(2) inhibition of shoot protein doubled. This result will likely have major implications for the ability of wheat to use NO(3)(-) as a nitrogen source under elevated CO(2).
authors.affiliation: Department of Vegetable Crops, One Shields Avenue, University of California, Davis, CA 95616. USA. ajbloom@ucdavis.edu
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Bloom
authors.forename: David R
authors.initials: DR
authors.lastname: Smart
authors.forename: Duy T
authors.initials: DT
authors.lastname: Nguyen
authors.forename: Peter S
authors.initials: PS
authors.lastname: Searles
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development; D018520:Plant Shoots / Q000254:growth & development; D018547:Plant Stems / Q000254:growth & development; D014908:Triticum / Q000187:drug effects / Q000254:growth & development*
chemical_list: D009566:Nitrates; D009573:Nitrites; D002245:Carbon Dioxide; D009584:Nitrogen