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The alternative respiratory pathway mediates carboxylate synthesis in white lupin cluster roots under phosphorus deprivation
Author(s) -
FLOREZSARASA IGOR,
LAMBERS HANS,
WANG XING,
FINNEGAN PATRICK M.,
RIBASCARBO MIQUEL
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12208
Subject(s) - alternative oxidase , lupinus , biochemistry , population , phosphorus , biology , chemistry , cytochrome c oxidase , mitochondrion , botany , demography , organic chemistry , sociology
Abstract Plant adaptations associated with a high efficiency of phosphorus ( P ) acquisition can be used to increase productivity and sustainability in a world with a growing population and decreasing rock phosphate reserves. White lupin ( L upinus albus ) produces cluster roots that release carboxylates to efficiently mobilize P from P ‐sorbing soils. It has been hypothesized that an increase in the activity of the alternative oxidase ( AOX ) would allow for the mitochondrial oxidation of NAD ( P ) H produced during citrate synthesis in cluster roots at a developmental stage when there is a low demand for ATP . We used the oxygen‐isotope fractionation technique to study the in vivo respiratory activities of the cytochrome oxidase pathway ( COP ) and the alternative oxidase pathway ( AOP ) in different root sections of white lupins grown hydroponically with and without P . In parallel, AOX protein levels and internal carboxylate concentrations were determined in cluster and non‐cluster roots. Higher in vivo AOP activity was measured in cluster roots when malate and citrate concentrations were also high, thus confirming our hypothesis. AOX protein levels were not always correlated with in vivo AOP activity, suggesting post‐translational regulation of AOX .