|
The agricultural productivity of temperate crop plants,
such as wheat, barley, potatoes and sugar beet, is limited
not only by growing conditions, but also by the performance
of the photosynthetic apparatus. These plants assimilate
carbon dioxide (CO2) by the C3 photosynthetic pathway,
which is inefficient at high light intensity, resulting
in photorespiration. Photorespiration results in a proportion
of the CO2 assimilated being lost due to glycine decarboxylase
(GDC) activity. Tropical crops, such as maize, use a
different pathway for photosynthesis (C4). This pathway
is more efficient at high light intensity and photorespiration
does not occur. Hence C4 crops do not lose CO2 and are
highly productive. Conventional genetic approaches have
failed to alter the photorespiratory properties of C3
crops. However, species with intermediate forms of photosynthesis
(C3-C4) exist and appear to have improved photosynthesis
characteristics and water-use efficiency. These intermediate
forms provided some ideas of genetic modifications that
might improve C3 plants. For example, GDC levels are
markedly low in leaf mesophyll cells whereas they are
high in the tissues surrounding the vascular bundles.
This project aims to transform C3 crops with recombinant
DNA constructs to generate a similar pattern of GDC
expression and to see if this improves crop performance
and water-use efficiency. This work aims to increase
the photosynthetic efficiency of temperate crop plants,
thereby increasing the yields of European crops.
|
