title: Photorespiration and nitrate assimilation: a major intersection between plant carbon and nitrogen.
abstract: C3 carbon fixation has a bad reputation, primarily because it is associated with photorespiration, a biochemical pathway thought to waste a substantial amount of the carbohydrate produced in a plant. This review presents evidence collected over nearly a century that (1) Rubisco when associated with Mn(2+) generates additional reductant during photorespiration, (2) this reductant participates in the assimilation of nitrate into protein, and (3) this nitrate assimilation facilitates the use of a nitrogen source that other organisms tend to avoid. This phenomenon explains the continued dominance of C3 plants during the past 23 million years of low CO2 atmospheres as well as the decline in plant protein concentrations as atmospheric CO2 rises.
authors.affiliation: Department of Plant Sciences, University of California at Davis, Davis, USA, ajbloom@ucdavis.edu.
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Bloom
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013696:Temperature
chemical_list: D009566:Nitrates; D010940:Plant Proteins; D002245:Carbon Dioxide; D008345:Manganese; D002244:Carbon; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen