Immunomodulation of plant function by in vitro selected single-chain Fv intrabodies

In this chapter, we discuss and compare the different concepts and examples as well as present the basic protocols for applying intrabody-based approaches in plants for the investigation of cell functions and plant cell-pathogen interactions. The immunomodulation strategy, a molecular technique that allows to interfere with cellular metabolism, signal transduction pathways, or pathogen infectivity, is based on the ectopic expression of genes encoding specific recombinant antibodies. This needs basic prerequisites to be successfully applied as resources and techniques to isolate specific recombinant antibodies with sufficient binding parameters to bind and to block even low-concentrated targets or to compete successfully with substrates and ligands. Also techniques and constructs to efficiently transform plants and to target recombinant antibodies to selected compartments are important requirements. Basic protocols for all these techniques are provided.