Comparison of natural and experimental host range of Beet severe curly top, Beet curly top Iran and Tomato yellow leaf curl viruses

Beet curly top Iran virus (BCTIV, genus Becurtovirus) and Beet severe curly top virus (BSCTV-IR, genus Curtovirus) induce beet curly top disease in different regions of Iran. In addition to sugar beet, tomato and pepper are important hosts of these viruses. Also tomato yellow leaf curl disease (TYLCD) is a serious disease of tomato in Iran. The Iranian isolate of Tomato yellow leaf curl virus (TYLCV-[Ab]), a severe strain of TYLCV (genus Begomovirus), is a major component of TYLCD in southern Iran. Until now, no information is available regarding comparative host range of these viruses. To determine the natural hosts of BSCTV-IR, BCTIV and TYLCV-[Ab], samples of sugar beet, tomato, pepper, turnip and spinach were collected from different regions in Fars province. For the experimental host range determination, a number of plants were grown in the greenhouse and their seedlings were agroinoculated with the infectious clone of each virus. The results showed that BSCTV-IR has a wider natural and experimental host range compared to BCTIV. These results indicated that member of Solanaceae, Brassicaceae, Fabaceae and Amaranthaceae are most frequently infected by BSCTV-IR and BCTIV. Natural host range of TYLCV-[Ab] seemed to be very narrow as, in the present study, this virus was isolated only from tomato. However, under greenhouse conditions, bean, nasturtium, petunia, redroot pigweed, datura, night shade and ground cherry were found to be infected by this virus.