Interaction of viruses causing beet curly top disease with Tomato yellow leaf curl virus in tomato plants under greenhouse conditions

Beet curly top Iran virus (BCTIV, genus Becurtovirus) and the severe strain of Beet curly top virus (BCTV-Svr, genus Curtovirus) are known as the causal agents of curly top disease in sugar beet and several other dicotyledonous plants in Iran. In addition to sugar beet, tomato and pepper are also economically important hosts of these viruses. Tomato leaf curl disease, one of the most important viral diseases of this crop, is caused by several species of the genus Begomovirus including the Iranian isolate of Tomato yellow leaf curl virus (TYLCV-[Ab]) that is a severe strain of TYLCV. TYLCV-[Ab] is a major component of tomato leaf curl disease in southern Iran. In this study, the interaction of BCTIV and BCTV-Svr with TYLCV-[Ab] in tomato plants was studied under greenhouse conditions. Analysis of the Real-time PCR data showed antagonistic interaction in simultaneous infection of BCTV-Svr or BCTIV with TYLCV-[Ab] as evidenced by decreasing in concentration of each virus involved in mixed infection in comparison to single infections. In general, in mixed infections, TYLCV-[Ab] was dominant and seemed more adaptive to tomato compared to BCTIV and BCTV-Svr.