Plants as bioreactors for protein production: avoiding the problem of transgene silencing

Plants are particularly attractive as large-scale production systems for pr oteins intended for therapeutical or industrial applications: they can be g rown easily and inexpensively in large quantities that can be harvested and processed with the available agronomic infrastructures. The effective use of plants as bioreactors depends on the possibility of obtaining high prote in accumulation levels that are stable during the life cycle of the transge nic plant and in subsequent generations. Silencing of the introduced transg enes has frequently been observed in plants, constituting a major commercia l risk and hampering the general economic exploitation of plants as protein factories. Until now, the most efficient strategy to avoid transgene silen cing involves careful design of the transgene construct and thorough analys is of transformants at the molecular level. Here, we focus on different asp ects of the generation of transgenic plants intended for protein production and on their influence on the stability of heterologous gene expression.