Effect of mycorrhizal fungus Rhizoglomus irregulare on the infection of tomato with Tomato bushy stunt virus

Tomato bushy stunt virus (TBSV) is one of the important tomato viruses in Iran and all over the world. In this study, the effect of mycorrhizae in Tomato bushy stunt virus infection was investigated. For this purpose inoculum of mycorrhizal fungus Rhizoglomus irregulare was added to the plant growing medium at the time of tomato transplanting and after four weeks, TBSV was inoculated mechanically to the plants. The rate of virus multiplication was evaluated by Real-time PCR at time intervals of 19, 25 and 31 days after inoculation. The treatments included control plants (C), plants infected with TBSV (V), mycorrhizal plants (M) and mycorrhizal plants infected with TBSV (MV). The results of investigating the amount of virus accumulation in plants showed its decrease in MV plants compared to V plants, and this decrease was more obvious in more advanced stages of the disease. Investigating the expression level of AGO2 and MYB33 genes also revealed that these genes had a significant increase in MV plants compared to V plants. This increase indicates an increase in the resistance of MV plants to the virus compared to V plants and it also confirms the lower reproduction of the virus in tomato plants inoculated with mycorrhiza. The results of this research show that the use of mycorrhizal fungi as a stimulant of the plant's defense system may be a good way to defend against this viral disease.