Tomato and Tobacco Phytoene Desaturase Gene Silencing by Virus-Induced Gene Silencing (VIGS) Technique

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 RNAdependent 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.