Geminivirus vectors for transient gene silencing in plants

Both RNA and DNA viruses have been engineered to serve as vectors for transient silencing in intact plants. Host gene sequences carried by the virus are seen by the plant as "foreign," and homologous gene-silencing machinery acts on both the viral vector RNA and the endogenous host gene mRNA. DNA viruses, such as geminiviruses, are advantageous for silencing because only their mRNAs are silenced and their DNA genomes continue to replicate and move. The conserved genome organization of geminiviruses and the fact that they can be cloned into Escherichia coli plasmids, propagated, and then inoculated into plants for infection simplifies the procedure for silencing specific chromosomal genes in intact plants. This chapter describes the development of a silencing vector from cabbage leaf curl virus for use in Arabidopsis and procedures for silencing two genes simultaneously.