The plasmid DNA delivered via PEI-SWCNTs was reported to be expressed transiently without integration into the genome. Therefore, it is possible that the DNA vector does not detach from PEI-SWCNT and that vector's functional units are expressed from the DNA while it is conjugated with PEI-SWCNTs but not from free DNA molecules. To consider this possibility, we used two clones of RNA viruses, Tobacco rattle virus (TRV), and Potato virus X (PVX). Once expressed inside the plant cell from a DNA molecule, the RNA genome of these viruses replicates independently. The use of RNA viruses can provide an excellent system to explore the possibility of low expression of large functional units from DNA-PEI-SWCNT. Modified TRVs can provoke virus-induced gene silencing (VIGS) of phytoene desaturase (PDS) gene transcripts and lead to systemic silencing of PDS transcript resulting in whitening of the leaves of N. benthamiana. To confirm that the extremely low initial transcription of the RNA genome can lead to the establishment of VIGS in N. benthamiana, TRV-PDS VIGS clones were conjugated with the PEI 30 -SWCNT. The conjugates were infiltrated into N. benthamiana leaves. As a positive control, the same clones were transformed into Agrobacterium and VIGS plasmids DNA only as negative control were infiltrated into N. benthamiana leaves. Infiltration of the TRV-PDS -PEI 30 -SWCNTs did not initiate the PDS transcript-based whitening in N. benthamiana leaves compared to the observed whitening of the leaves in plants infiltrated with Agrobacterium containing the TRV-PDS VIGS system (Fig. ). To reconfirm our experimental observations, another RNA virus PVX-GFP system was selected, whereupon successful infection, PVX results in the systemic spread of GFP to the whole plant. Similar to no infection from TYLCV and TRV, infiltration of the PVX-GFP-PEI 30 -SWCNT did not result in any expression and systemic movement of GFP in N. benthamiana plants (Fig. ).