Functional Whole Plant Modelling - The Missing Link between Molecular Biology and Crop Improvement?

Recent progress in molecular technologies for genome sequencing and functional genomics has not yet contributed significantly to practical crop improvement associated with key complex traits, such as water productivity. This is largely because whole plant phenotypic responses associated with complex traits do not scale directly from the level of molecular action. The complexities of interactions within the plant and of the plant with its environment confound application of molecular scale knowledge. Here, we argue that functional whole plant modelling has a critical role to play as a linking technology between phenotypic and molecular approaches to plant breeding and crop improvement. Plant models, which are simplified mathematical representations of the interacting biological and environmental components of the dynamic plant/crop system, offer potential for understanding and predicting gene-to-phenotype relationships for complex traits. However, existing descriptive agronomic models do not contain the degree of biological functional detail required. A greater emphasis on explanatory approaches via understanding the dynamics of underpinning crop growth and development processes is required. Such functional whole plant models can be used to predict trajectories of organism status throughout the crop cycle as emergent consequences of genetic (G), management (M) and environmental (E) influences. This will provide the basis to – - dissect the functional physiology underpinning genetic variation in key adaptive traits, - identify genomic regions in a way that reduces environment and genotype context dependencies, and - predict crop growth and yield consequences in a manner that incorporates G*M*E effects. A generic framework is being developed for these purposes in cereal crops. Examples of its use in linking molecular and plant scales to support crop improvement are presented