Tomato bushy stunt virus (TBSV) and Tomato mosaic virus (ToMV) are important economic pathogens in tomato fields. Rhizoglomus irregulare is a species of arbuscular mycorrhizal (AM) fungus that provides nutrients to host plants. To understand the effect of R. irregulare on the infection by TBSV/ToMV in tomato plants, in a completely randomized design, five treatments, including uninfected control plants without AM fungi (C), uninfected control plants with AM fungi (M) TBSV/ToMV-infected plants without AM fungi (V), TBSV/ToMV-infected plants before mycorrhiza (VM) inoculation, and inoculated plants with mycorrhiza before TBSV/ToMV infection (MV), were studied. Factors including viral RNA accumulation and expression of Pathogenesis Related proteins (PR) coding genes including PR1, PR2, and PR3 in the young leaves were measured. For TBSV, a lower level of virus accumulation and a higher expression of PR genes in MV plants were observed compared to V and VM plants. In contrast, for ToMV, a higher level of virus accumulation and a lower expression of PR genes in MV plants were observed as compared to V and VM plants. These results indicated that mycorrhizal symbiosis reduces or increases the viral accumulation possibly via the regulation of PR genes in tomato plants.

Background and Aims: Celery mosaic virus (CeMV) is one of the causal agents of viral diseases in celery (Apium graveolens). CeMV is a member of the Potyvirus genus in Potyviridae family. The virus is naturally transmitted by aphids in a non-persistent manner. During growing season 2006-2007 viral disease symptoms were observed in celery fields grown in Tehran Province (Bage daneshkade, Mohamadshahr, Varamin, Asgarabad, Hesarak and Savojbolagh) and suspected CeMV infected plants were sampled. Methods: Serological assays with specific antisera against CeMV and other potyviruses revealed that 5.42% of the samples were infected with CeMV in Tehran province. Biologically purified CeMV isolate was mechanically inoculated on test plants for host range studies. Results: The virus caused chlorotic local lesions on Chenopodium quinoa and C. amaranticolor. It also produced mosaic, vein clearing and leaf deformations symptoms on Apium graveolens. Molecular mass of CeMV coat protein was estimated about 38.36 kDa using SDS-PAGE and was approved by western blotting using CeMV specific polyclonal antibody. A DNA fragment of about 650bp was amplified by RT-PCR using CeMV infected crude RNA and universal primer pair for potyviruses coat protein genome. Conclusion: This is the first study on this virus in Iran (Tehran Province).