Crop systems biology as an avenue to bridge applied crop science and fundamental plant biology

Plant biologists, agronomists and breeders alike have been constantly facing challenges in narrowing genotype-phenotype gaps. Plant systems biology, as first recognized, seems to target those phenotypes at molecular, sub-cellular, or cellular levels. To emphasize the importance of bridging this gap for understanding and directionally modifying phenotypes relevant to the real-world challenges for agriculture, the concept `crop systems biology' seems more appropriate. This new concept acknowledges the complementarity of the roles of modern plant biology, traditional crop physiology and advanced crop modelling in improving yield and resource use efficiencies of major crops. As a first step, biochemical modules of photosynthesis and molecular marker-based quantitative trait locus information were incorporated into existing crop models. These case studies underline that current modelling shows promise in studying complex crop traits. For further progress, crop models should be upgraded based on understandings of complicated phenomena at lower organizational levels. We expect that this crop systems biology approach will ultimately be instrumental in realizing the expected roles of in silico modelling in narrowing genotype-crop phenotype gaps, and in understanding genotype-by-environment interactions at crop level.