Expression and purification of heterologous proteins in plant tissue using a geminivirus vector system

In the past, plant molecular biologists have relied on Escherichia coli, baculovirus and other expression systems to produce plant proteins to quantities sufficient for biochemical analysis. However, such expression systems often result in the production of proteins which possess improper posttranslational modifications. Here, we present a plant virus-based expression system superior to those currently available. We demonstrate that bean yellow dwarf geminivirus (BeYDV) replicates and expresses foreign proteins at high levels in tobacco, Arabidopsis, and other dicotyledonous plants, making it more universal than plant RNA viruses with restricted host ranges which are currently used as expression systems. The DNA-based nature of the BeYDV genome renders it stable for the incorporation of large plant open reading frames, and gives it an advantage over other plant virus-based expression systems which possess insert size restrictions. Using this expression system, the rapid accumulation of a novel Arabidopsis-derived mitogen-activated protein kinase to levels sufficient for standard biochemical analysis is demonstrated.