Background and Aims: Virus-Induced Gene Silencing (VIGS) is a virus vector technology that exploits antiviral defense mechanism. By infecting plants with recombinant viruses containing host genes inserted in the viral genome, VIGS achieves the RNA silencing process. The purpose of this study was to investigate the possibility of tomato (Lycopersicon esculentum Mill.) and tobacco (Nicotiana benthamiana) phytoene desaturase (PDS) gene silencing, using VIGS technique by VIGS vector containing tomato PDS.

Methods: PDS gene encodes one of the important enzymes in the carotenoid biosynthesis pathway. In this method Tobacco rattle tobravirus (TRV) vectors including pTRV₁، pTRV₂ and pTRV₂PDS were used. The pTRV₂PDS vector carried inserts derived from tomato PDS gene. Vectors were transformed into Escherichia coli strain DH₅α. Agrobacterium tumefaciens strain GV3101 cells were transformed by the vectors containing specific genes.

Results: Colony PCR with specific primers proved the presence of the PDS and RNA-dependent RNA polymerase genes in selected agrobacterium random colonies. Agrobactrium containing pTRV₁، pTRV₂ and pTRV₂PDS was inoculated into induction media culture. Finally, acetosyringone was added to pTRV₁ culture and then pTRV₁ and pTRV₂PDS cultures mixed in a 1:1 ratio. Mixed culture was infiltrated into the test plant seedlings using 1ml needless syringe.

Conclusion: Results showed the gene silencing in the form of photobleaching and mosaic occurred in tomato and tobacco plant leaves, respectively. However, plant infiltration with pTRV₁ and pTRV₂ (without PDS gene as control) mixed culture did not show any photobleaching.