Abstract

Synthetic Biology is an emerging field that employs engineering principles for constructing genetic systems. The approach is based on the use of well characterised and reusable components, and numerical models for the design of biological circuits – in a way that has become routine in other fields of engineering. Synthetic Biology is providing a conceptual and practical framework for the systematic engineering of gene expression and behaviour in microbes, facilitating the design of novel regulatory networks, including synthetic oscillators, switches, logic gates, intercellular signaling systems and metabolic pathways. Synthetic Biology approaches also show great potential for the engineering of multicellular systems. (1) The greatest diversity of cell types and biochemical specialisation is found in multicellular systems, (2) the molecular basis of cell fate determination is increasingly well understood, and (3) it is feasible to consider creating new tissues or organs with specialized biosynthetic or storage functions by remodelling the distribution of existing cell types. Of all multicellular systems, plants are the obvious first target for this type of approach. Plants possess indeterminate and modular body plans, have a wide spectrum of biosynthetic activities, can be genetically manipulated, and are widely used in crop systems for production of biomass, food, polymers, drugs and fuels. Current GM crops generally possess new traits conferred by single genes, and expression results in the production of a new metabolic or regulatory activity within the context of normal development. However, cultivated plant varieties often have enlarged flowers, fruit organs or seed, and are morphologically very different from their wild-type ancestors. Recent genetic studies have provided detail of the molecular processes underlying plant development. The next generation of transgenic crops will contain small gene networks that confer self- organizing properties, and the ability to reshape patterns of plant metabolism and growth. The ability to assemble new feedback regulated genetic circuits and developmental regulators in planta will allow the engineering of stable new patterns of gene activity, and targeted reprogramming of the number and arrangement of cell types in natural organ systems. Misregulation of key transcription regulators can promote or repress the formation of particular cell types, and coordinated misexpression can result in the ectopic conversion of cell fates. This would provide a means to modify plant form and biosynthetic activities, with the ultimate prospect of producing neomorphic structures suited to bio production. We are assembling tools for the engineering of plant systems. We have constructed a software environment for numerical description of multicellular plant behaviour, which provides a model for the physical basis of plant cell growth and interaction within a multicellular tissue (CellModeller). Genetic and biophysical models can be described and modelled using finite element analysis methods to allow the design and testing of new morphogenetic programs in silico.