Natural Infection Rate of Known -Susceptible Hosts and the Influence of the Host Plant on the Virus Relationship With MEAM1.

(ToCV; genus , family ) was identified in tomato crops in São Paulo State, Brazil, in 2006. Management strategies to control external sources of inoculum are necessary, because chemical control of the whitefly vector Middle East-Asia Minor 1 (MEAM1) has not efficiently prevented virus infections and no commercial tomato varieties or hybrids are resistant to this crinivirus. We first evaluated the natural infection rate of some known wild and cultivated ToCV-susceptible hosts and their attractiveness for MEAM1 oviposition. was the most susceptible to natural infection in all six exposures in 2018 and 2019. No plants of 'Dahra' or became infected. 'Napoli' had only two infected plants of 60 exposed. and were the least preferred, and and were the most preferred for whitefly oviposition. In addition, from 2016 to 2019, we surveyed different tomato crops and the surrounding vegetation to identify ToCV in weeds and cultivated plants in the region of Sumaré, São Paulo State. Only , vila vila (), and were found naturally infected, with incidences of 18, 20, and 1.4%, respectively. Finally, we estimated the ToCV titer (U.S. and Brazilian isolates ToCV-FL and ToCV-SP, respectively) by quantitative reverse transcription PCR in different ToCV-susceptible host plants and evaluated the relationship between virus acquisition and transmission by MEAM1. The results clearly showed significant differences in ToCV concentrations in the tissues of ToCV-susceptible host plants, which appeared to be influenced by the virus isolate. The concentration of the virus in plant tissues, in turn, directly influenced the ToCV- MEAM1 relationship and subsequent transmission to tomato plants. To minimize or prevent damage from tomato yellowing disease through management of external sources of ToCV, it is necessary to correctly identify potentially important ToCV-susceptible hosts in the vicinity of new plantings.