Agriculture Reference
In-Depth Information
For photosynthesis, not only leaf nitrogen content but
also nitrogen use within a leaf is suggested to be related
to the temperature acclimatization. Changes in nitrogen
partitioning among photosynthetic components can be a factor
responsible for changes in the temperature dependence of the
photosynthetic rate, and thus may affect the photosynthetic
rate at the growth temperature. It has also been reported that
the temperature dependence of Rubisco kinetics changes with
growth temperatures.
Temperature dependence of the respiration rate is
considered to be determined by the maximum activity of
respiratory enzymes, availability of substrates and/or demand
for respiratory energy. It has been reported that temperature
acclimatization of respiration involves increases in respiratory
capacity by increasing the capacity per mitochondrion or
increasing the number of mitochondria, the mitochondrial
density and the density of cristae within mitochondria. Thus,
temperature acclimatization of respiration could be linked to
changes in the enzyme capacity (Yamori et al. 2009).
Much of the energy and carbon skeletons necessary for
biosynthesis and cellular maintenance are produced by plant
respiration. Under some conditions (e.g., excess irradiance)
respiration (R) may also help minimize the formation of
potentially damaging reactive oxygen species (ROS) through
oxidation of excess cellular redox equivalents (Maxwell et al.
2009). R is also crucial for (1) the production of ascorbate (Millar
et al. 2003), a necessary component of the protective xanthophyll
and glutathione cycles, (2) the maintenance of photosynthetic
activity, largely because of the energy demands of sucrose
synthesis (Kromer 1995), and (3) regulating pathogen defence
processes. R also plays an important role in determining the
carbon budget of individual plants and the concentration of
