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Plant mitochondria electron partitioning is independent of short‐term temperature changes
Author(s) -
MACFARLANE CRAIG,
HANSEN LEE D.,
FLOREZSARASA IGOR,
RIBASCARBO MIQUEL
Publication year - 2009
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/j.1365-3040.2009.01953.x
Subject(s) - cucurbita pepo , alternative oxidase , respiration , chemistry , electron transport chain , cytochrome c oxidase , oxygen , photosynthesis , botany , q10 , horticulture , analytical chemistry (journal) , environmental chemistry , biochemistry , biology , mitochondrion , organic chemistry
We tested the hypotheses that relative activity of the less efficient alternative oxidase (AOX) path changes with diurnal temperature changes, and thus changes carbon use efficiency with temperature. The activities of the alternative and cytochrome oxidase (COX) paths in plant tissues of three species were determined by measuring 18 O/ 16 O discrimination and total respiration from 17 to 36 °C. A new, more accurate method for calculating oxygen uptake rate from the mass spectrometry data was developed. Total carbon use efficiency was calculated from the ratio of respiratory heat and CO 2 rates measured from 10 to 35 °C. Oxygen isotope discrimination (22.9 ± 0.4‰) and AOX participation were invariant with temperature in leaf tissue of Cucurbita pepo , Nicotiana sativa and Vicia faba , thus falsifying the first part of the hypothesis. Stress responses of respiration at the temperature extremes limited the range for which carbon use efficiency could be accurately measured to 15–30 °C in N. sativa , to 10–25 °C in C. pepo and to 20–30 °C in V. faba . Carbon‐use efficiency was invariant at these temperatures in these species, demonstrating that changes in other pathways that would vary carbon‐use efficiency were also invariant with temperature.