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Pinus sylvestris switches respiration substrates under shading but not during drought
Author(s) -
Fischer Sarah,
Hanf Stefan,
Frosch Torsten,
Gleixner Gerd,
Popp Jürgen,
Trumbore Susan,
Hartmann Henrik
Publication year - 2015
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13452
Subject(s) - respiration , shading , carbohydrate , respiratory quotient , scots pine , botany , substrate (aquarium) , biology , respiratory system , photosynthesis , chemistry , horticulture , pinus <genus> , biochemistry , ecology , art , anatomy , visual arts
Summary Reduced carbon (C) assimilation during prolonged drought forces trees to rely on stored C to maintain vital processes like respiration. It has been shown, however, that the use of carbohydrates, a major C storage pool and apparently the main respiratory substrate in plants, strongly declines with decreasing plant hydration. Yet no empirical evidence has been produced to what degree other C storage compounds like lipids and proteins may fuel respiration during drought. We exposed young scots pine trees to C limitation using either drought or shading and assessed respiratory substrate use by monitoring the respiratory quotient, δ 13 C of respired CO 2 and concentrations of the major storage compounds, that is, carbohydrates, lipids and amino acids. Only shaded trees shifted from carbohydrate‐dominated to lipid‐dominated respiration and showed progressive carbohydrate depletion. In drought trees, the fraction of carbohydrates used in respiration did not decline but respiration rates were strongly reduced. The lower consumption and potentially allocation from other organs may have caused initial carbohydrate content to remain constant during the experiment. Our results suggest that respiratory substrates other than carbohydrates are used under carbohydrate limitation but not during drought. Thus, respiratory substrate shift cannot provide an efficient means to counterbalance C limitation under natural drought.