Gene Downregulation in Potato Roots Using Agrobacterium rhizogenes-Mediated Transformation

Agrobacterium rhizogenes has the ability to transform plant cells by transferring the T-DNA from the Ri plasmid to the plant cell genome. These infected plant cells divide and organize the formation of adventitious roots, called hairy roots. When the A. rhizogenes is additionally transformed with a binary vector, the cells infected can indeed be transformed with this second T-DNA producing transgenic hairy roots. In this chapter, we present the protocol to produce transgenic hairy roots from in vitro potato (Solanum tuberosum) plants injected with transformed A. rhizogenes, generating plants with a wild-type shoot and a transgenic root system. Specifically, we detail the procedure to obtain in vitro-cultured hairy roots with a downregulated gene of interest, by using a Gateway-based binary vector able to produce a RNA hairpin triggering the RNA interference mechanism (hpRNAi). We also present the protocol to analyze the downregulation of the target gene in hairy roots by means of reverse-transcription reaction followed by real-time PCR (qPCR).