nt protein (GFP) was detected using the primary antibody Living Colors Full-Length A.v. Polyclonal Antibody (Clontech) at a 1∶1000 dilution and the secondary anti-rabbit IgG conjugated to horseradish peroxidase (Sigma) at a 1∶10000 dilution. ECL reagent (GE Lifesciences) was used for visualization by chemiluminescence upon exposure to Kodak Biomax MS film.

β-glucuronidase (GUS) detection {#s4e}
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*N. benthamiana* leaf punches were homogenized in 1× Passive Lysis Buffer (Promega) and GUS activity (uidA gene) was quantified using the 4-methylumbelliferone assay as described [@pone.0021330-Jefferson1]. The GUS activity is reported as an average of seven independent replicates per inoculum mix, each replicate consisting of six tissue punches from an individual leaf.

Quantitative RT-PCR {#s4f}
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Expression analysis of endogenous *SCL6-III* gene was done as follows. RNA samples were treated with Turbo DNA-Free DNase (Ambion) and normalized to 5 ng/µL. Primers for qRT-PCR were selected using Applied Biosystems Primer Express version 2.0 software ([Table S1](#pone.0021330.s005){ref-type="supplementary-material"}). *Arabidopsis* rRNA 18S was used for normalization. qRT-PCR was carried out using the QuantiTect SYBR Green RT-PCR Kit (Qiagen) in an ABI7900HT following Qiagen manufacturer recommendations with a 60°C annealing temperature and 40 cycles. A final primer concentration of 400 nM for genes of interest and 100 nM for 18S control was used.

For *Arabidopsis* transgene expression analysis, leaf tissue was homogenized in a 1∶1 mixture of PBS, pH 7.4 (no CaCl~2~ or MgCl~2~) (Gibco) and Nucleic Acid Purification Lysis Solution (Applied Biosystems). The homogenate was then filtered through a 10 µM melt-blown polypropylene media column, and RNA subsequently bound by filtering through 0.45 µM PVDF membrane (Whatman). RNA wash buffer (Applied Biosystems) was used to rinse the membrane, and RNA was then eluted. RT-PCR and analysis was carried out using Taqman Mas