Differential expression of HSP90 ,AGO1 and AGO4 genes in tomato infected by Cucumber mosaic virus

Cucumber mosaic virus (CMV) is a type member of Cucumovirus genus in the family Bromoviridae. In this research, the expression profile of several genes related to development and methylation was tested in a sensitive variety of tomato infected by CMV-Fny. Tomato inoculation was carried out using a standard isolates of CMV (Fny). To this aim, transcripts of RNA1, RNA2 and RNA3 of CMV were transcribed and then, inoculated using sap inoculation on tobacco plants at the four-leaf stage. After symptoms induction, leaf samples were collected at 7, 14 and 21 days post inoculation (dpi). The virus infection was confirmed by RT-PCR using CMV-CP specific primers corresponding coat protein gene. The expression of several genes related to development and methylation including Hsp90, AGO1 and AGO4 was tested by real-time PCR. The results showed that the expression of HSP90 was decreased after infection by CMV compared to healthy plans. In addition, the expression of AGO1 was increased at 7 and 14 dpi whereas the expression was decreased compared to healthy plans at 21 dpi. The expression of AGO4 which has the role in plant defense was increased in infected tomato plants at 14 and 21 dpi and AGO4 expression was decreased compared to healthy plant in 7 dpi. It seems, changes in AGOs expression refer to late induction of plant resistance against the virus infection.