This proposal aims at genetically engineering major EU crops to improve their phosphate efficiency in order to maximise their yield potential. This relates to their ability to acquire phosphate from the environment, as well as to optimise the utilization of phosphate on the organismic, cellular, subcellular and molecular levels. This will ultimately lead to the generation of crops producing high yield with a lowered input. In order to accomplish this, a multi-disciplinary approach is chosen to devise means enabling the targeted manipulation of phosphate efficiency. Mainly potato as a model crop plant will be used to assess diverse strategies for their feasibility. Phosphate acquisition efficiency will be manipulated through enhancing the capacity of the root system to secrete protons or organic acids, to release phosphate from organic compounds or to acquire carbon from other organs in order either to enlarge the root surface, or to enhance carbon flow into the symbiont in a mycorrhizal interaction. Furthermore, other plant genes, specifically expressed during phosphate starvation, will be isolated and subjected to a functional analysis in transgenic plants in order to devise novel means to engineer plant phosphate acquisition.
Phosphate utilization efficiency is subject to manipulation on the phosphate distribution within the whole plant, as well as on the cellular, subcellular and molecular level. It is envisaged to clone genes responsible for the translocation of phosphate from the roots into the shoots, and to overexpress these in transgenic plants in order to enhance translocation capacities. Furthermore, the study of transgenic plants, where major pools for phosphate storage have been removed, will give some detailed insights into the regulation of phosphate distribution between different plant organs. The interrelation between carbohydrate metabolism and phosphate distribution will be investigated using transgenic plants with severe distortions in carbohydrate partitioning and allocation. This will allow the development of strategies to optimise phosphate utilization with respect to maximal carbon accumulation in storage organs.
On the cellular, subcellular and molecular the mechanisms maintaining the phosphate homeostasis within the cytoplasm of plant cells will be analysed. To this end, either the transport capacity of the tonoplast for phosphate will be manipulated, or novel pools for phosphate will be established in different subcellular compartments of transgenic plants.
The thorough study of the resulting physiological effects will enable the optimization of the subcellular phosphate distribution for a maximal photosynthetic capacity of plant leaves. Here again, the interrelation of carbohydrate metabolism and phosphate distribution will be analysed using transgenic plants which are impaired in photosynthetic carbon metabolism. Concepts, which have been proven valuable will be ultimately transferred to crop plants with higher economic value such as sugar beet, maize and rye grass. This novel approach unifies diverse expertise on plant physiology, biochemistry, molecular biology and genetics, including plant breeders, and will generate additional prospects for crop improvement through genetic engineering with the goal to obtain low input/high yield plants.
Funding SchemeCSC - Cost-sharing contracts
4421 AJ Kapelle
BS18 9AF Bristol
2333 CB Leiden
6703 BD Wageningen