The continuing rise in atmospheric CO2 concentrations is driving a rapid increase in ambient temperatures. The accompanying environmental changes will progressively reduce the area of arable land available and thus pose a grave threat to global food security. The situation is exacerbated both by exponential population growth and increased demand for crop plants as sources of renewable energy or high-value products. The foreseeable intensification of competition between agronomical and industrial use makes it imperative that the available supply of cropland be used more efficiently. During the Green Revolution that began in the 1960s, significant increases in yield could be achieved by more effective farming strategies, innovations in fertilization, and the introduction of dwarfing genes into important crop species like rice (Oryza sativa) and wheat (Triticum aestivum). The last resulted in a shift of carbon allocation within the plant from the vegetative tissue to the grain. The stunted growth phenotypes of the new varieties also reduced yield losses caused by fertilization-based lodging effects. In recent years, conventional breeding endeavors have been unable to maintain the resulting high rates of grain yield increase per unit area of arable land, and the beneficial effects associated with the Green Revolution have virtually ceased due to the already widespread cultivation of improved varieties.
Currently the most promising approaches to improving crop yield appear to be those based on the genetic engineering of developmental or bioenergetic processes, such as photosynthesis.
These approaches offer the prospect of a renewal of the Green Revolution, which is urgently required tomeet the continuously increasing demand for superior high-yield crop varieties for human sustenance and industrial applications in the future.
This article will highlight genetic approaches to the remodeling of the primary metabolism of photosynthesis with a view to establishing the basis for a sustainable increase in yield and biomass production in crop plants.