Host range and natural infection of tomato chlorosis virus in weeds collected in Central Brazil

Tomato chlorosis virus (ToCV), transmitted by whiteflies, is an important virus that infect tomato plants worldwide. The incidence of ToCV in tomato crops in Brazil is usually high, especially in the Distrito Federal and the state of Goias, in the central part of the country. We conducted a survey in central Brazil to detect natural infections of ToCV in weeds near tomato plants with typical criniviral symptoms to determine the possible causes of its high incidence. We also conducted an experimental host range study using a Brazilian ToCV isolate, ToCV-BR. ToCV was only detected in three out of 19 weed species collected under natural conditions: Solanum americanum, Nicandra physaloides and Amaranthus viridis. Although these species are the most important weeds, occurring at high frequencies associated with tomato crops in Brazil, the number of weed species infected by ToCV was low in the vicinity of tomato fields. In experimental trials of whitefly (Bemisia tabaci) transmission, the ToCV-BR isolate infected 10 out of 50 plant species tested. The natural abundance of both whiteflies and ToCV-susceptible plants in the field throughout the year may affect the incidence of ToCV in tomato in central Brazil.