Differential Response of Mycorrhizal Plants to Tomato bushy stunt virus and Tomato mosaic virus Infection.

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.

Occurrence and distribution of Potato virus Y strain N (PVY(N)) on celery in Iran.

Celery (Apium graveolens) is an important crop grown in many countries. Different types of diseases present a major constraint to Celery production and can lead to significant reductions in yield Potato Virus Y, the type member of the genus Potyvirus(family Potyviridae) is one of the causal agents of viral diseases in crops. In the present study, PVY occurring in celery fields was determined as the causal agent of mosaic disease of celery (Apium graveolens). The virus is naturally transmitted by aphids in a non-persistent manner. During growing seasons 2006-2007 celery fields were visited through Tehran Province and a total 332 sample based on selection of plants expressing symptoms like mosaic, vein clearing and mottling were collected. By using serological method (DAS-ELIZA) with specific antiserum of PVY (DSMZ-AS-0137.403) 17.64% of the samples were infected with PVY .The reaction of PVY infected samples were positive in TAS-ELIZA with specific monoclonal antibody (MAbs) of PVYN strain (DSMZ-AS-403.1). PVY N strain isolated from celery was reported for the first time in Iran and in the world in this survey.