Antibody-based metabolic engineering in plants

Genetic engineering is a powerful tool for the manipulation of cellular metabolism and the development of plant varieties with enhanced biological and nutrional functions. Several strategies are available for the in vivo modulation of enzymatic activities, allowing metabolic flux to be directed towards desired biochemical products. Such strategies include the simultaneous expression and/or suppression of multiple genes encoding rate-limiting enzymes, ectopic expression of transcription factors, and the RNA-based inhibition of catabolic enzymes. As an alternative approach, recombinant antibodies expressed in plants have been used to inactivate or sequestrate specific host proteins or compounds, resulting in significant changes to metabolic pathways. The impact of this approach depends on prudent selection of the target antigen, careful antibody design, appropriate subcellular targeting and stable accumulation of the recombinant antibodies in planta. Here, we describe the current status of antibody-based metabolic engineering in plants, discuss procedures for the optimisation of this technology and consider the remaining challenges to its widespread use.