title: Seasonal variation of leaf respiration and the alternative pathway in field-grown Populus × canadensis.
abstract: The temperature response of plant respiration varies between species and can acclimate to changing temperatures. Mitochondrial respiration in plants has two terminal oxidases: the cytochrome c oxidase (COX) and the cyanide-resistant alternative oxidase (AOX). In Populus × canadensis var. italica, a deciduous tree species, we investigated the temperature response of leaf respiration via the alternative and cytochrome pathways, as well as seasonal changes in these pathways, using the oxygen isotope fractionation technique. The electron partitioning through the alternative pathway (τ(a) ) increased from 0 to 30-40% with measurement temperatures from 6 to 30°C at all times measured throughout the growing season. τ(a) at the growth temperature (the average temperature during 3 days prior to sampling) increased from 12 to 29% from spring until late summer and decreased thereafter. Total respiration declined throughout the growing season by 50%, concomitantly with decreases in both AOX (64%) and COX (32%) protein abundances. Our results provide new insight into the natural variability of AOX protein abundances and alternative respiration electron partitioning over immediate and seasonal timescales.
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. stephanieysearle@gmail.com
authors.forename: Stephanie Y
authors.initials: SY
authors.lastname: Searle
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Turnbull
mesh_terms: D050260:Carbohydrate Metabolism; D019069:Cell Respiration; D003433:Crosses, Genetic; D003576:Electron Transport Complex IV / Q000378:metabolism; D004583:Electrons; D053858:Metabolic Networks and Pathways; D024101:Mitochondrial Proteins / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D032107:Populus / Q000166:cytology / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D012621:Seasons; D013696:Temperature; D000099188:Alternative Oxidase
chemical_list: D003576:Electron Transport Complex IV; D024101:Mitochondrial Proteins; D009584:Nitrogen; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase