Challenges for Engineering Plant Enzymes and Pathways


While much headway is being made in gene discovery and enzyme engineering efforts, the use of this basic science knowledge to develop novel crops is somewhat lagging. This is because plant metabolism is more complicated than previously assumed, with pathways containing unexpected genetic redundancy in addition to being under the control of multiple biochemical and genetic regulatory circuits (Sweetlove and Fernie, 2005). Superimposed on this complexity are cell biology issues such as the heterogeneity of tissues and developmental programs. While studies at the whole plant level pose significant challenges in terms of heterogeneity, stable-isotope metabolic flux analyses have provided new insight into the role of RuBisCO in carbon fixation in seeds (Schwender et al., 2004a). Because metabolic flux analysis provides a direct way of measuring the effects of genetic perturbations on metabolism, it is envisaged that this technique will become increasingly valuable for interpreting future genetic engineering efforts (Schwender et al., 2004b).

The application of engineering approaches in the emerging discipline of plant systems biology, that is, of high-throughput data collection along with direct flux measurements, computer modeling, and simulation, will undoubtedly provide the basis for integrating our knowledge and creating engineered crops designed to meet the increasing needs of mankind.