Crop systems biology : an approach to connect functional genomics with crop modelling

The response of the whole crop to environmental conditions is a critical factor in agriculture. It can only be understood if the organization of the crop system is taken into account. A popular view in modern science is that genomics (and other `omics¿) will provide knowledge and tools to allow the characteristics of the crop to be altered for improved actual and potential crop yields, increased resource use efficiency and enhanced crop system health. As a result of this view, (molecular) plant systems biology has been considered as an approach to assist crop improvement for increased production, via modelling `how things work¿ in (sub-)cellular units. However, phenotypes at the crop level, for example, as expressed in grain yields, are extremely complex, and not only achieved by molecular pathways but also through multiple intermediate metabolic and physiological processes. These processes are controlled by numerous genes whose effects and expression are highly dependent on environmental perturbations. Current prevailing initiatives for (molecular) plant systems biology so far have put little emphasis on bringing the `omics¿ information to the crop level. Here, crop systems biology is presented as a complementary modelling approach to assist plant-breeding programmes to improve the yield and related resource use efficiencies of major crops. This crop systems biology approach honours the combined role of modern functional genomics and traditional sciences (such as crop physiology and biochemistry) in understanding and manipulating crop phenotypes relevant to agriculture. A stepwise routine for the development of crop systems biology models is proposed. Ultimately, these models should enable in silico assessment of crop response to genetic fine-tuning under defined environmental scenarios