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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 pTRV 1 ،pTRV 2 and pTRV 2 PDS were used. The pTRV 2 PDS vector carried inserts derived from tomato PDS gene. Vectors were transformed into Escherichia coli strain DH 5 α. 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 pTRV 1 ،pTRV 2 and pTRV 2 PDS was inoculated into induction media culture. Finally, acetosyringone was added to pTRV 1 culture and then pTRV 1 and pTRV 2 PDS 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 pTRV 1 and pTRV 2 (without PDS gene as control) mixed culture did not show any photobleaching.

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Sugarcane is an important industrial plant which cultivated in the most arid and semiarid regions. Due to climate change and anthropogenic activities, the sugarcane field damage due to salt deposition and the cultivation of sugarcane has been posed a major threat in the region. To address this issue, the identification of salinity tolerant cultivars would be a suitable strategy to minimize yield loss in the area. MicroRNAs (miRNAs) play important roles in regulating gene expression. The monitoring of the expression of miRNAs and their targeted genes could provide deeper insight into the molecular stress mechanism and screen tolerant cultivars. Our aim was to assess the expression of nine candidate miRNAs and their corresponding targeted genes among the studied sugarcane cultivars under salinity condition, leading to identify the salt-tolerant cultivar. To achieve our goal, a two-factorial experiment with three sugarcane cultivars (CP-48, CP-57, CP-69) and two salinity levels (0 and 8 ds/m) was conducted. One-way ANOVA indicated that there was a significant difference between miRNAs and targeted gene expression. The highest reduction of miRNAs expression was occurred in miR160 while the lower one was happening in miR1432. The data also indicated that the higher and the lowest of targeted genes were in miR160 and miR393 respectively. Among studied cultivars, the CP-57 showed poor performance while CP-69 expresses a superior tolerance to salt stress. Taken together, these results suggested that the screening of well adapted cultivars under salt conditions would be appropriate solutions to combat salinity stress in saline lands.