USDA-ARS, 1636 E. Alisal St., Salinas, CA 93905
University of Florida, Gulf Coast Research and Education Center, 5007 60th St. E., Bradenton 34203
University of Puerto Rico, Agricultural Experiment Station, P.O. Box 21360, San Juan, 00928
University of Puerto Rico, Lajas Substation, Lajas, 00667
Symptoms of interveinal chlorosis, necrotic flecking, thickening, and rolling of leaves were observed on leaves of field-grown tomato (Lycopersicon esculentum) plants in Jauna Diaz, Puerto Rico. These symptoms are indicative of those produced by the whitefly-transmitted criniviruses, Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV) (1). Samples collected from two symptomatic plants were examined by leaf dip and were found to contain long flexuous rods approximately 800 nm in length, characteristic of criniviruses. Symptomatic leaves were used for extraction of total nucleic acid and for whitefly transmission studies. The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is a highly efficient vector of TICV, but an inefficient vector of ToCV, whereas the banded wing whitefly, T. abutilonea (Haldeman), is an efficient vector of ToCV but does not transmit TICV (2). Whiteflies of both species were allowed to feed separately on symptomatic tomato leaves for 24 h and then transferred to healthy Physalis wrightii and Nicotiana benthamiana indicator plants. Symptoms characteristic of ToCV infection developed on 3 of 3 P. wrightii plants and 2 of 3 N. benthamiana plants following transmission by T. abutilonea. Only 1 of 3 P. wrightii plants developed such symptoms following transmission by T. vaporariorum, while no N. benthamiana plants developed symptoms, suggesting that the virus responsible for the tomato disease was ToCV. Dot blot hybridizations were performed on total nucleic acids extracted from 0.1 g of symptomatic leaves of field samples using probes specific for TICV or ToCV (2), as well as probes specific for four additional criniviruses. Symptomatic and asymptomatic leaves of plants in transmission tests, as well as comparable leaves from control plants, were also tested by dot blot. Although no criniviruses could be detected by dot blot in the original tomato tissue, these hybridizations identified ToCV in all symptomatic plants from the transmission experiments, confirming the presence of ToCV in Puerto Rico. No additional criniviruses were detected in any samples, and negative controls were virus-free. This is the first time a tomato crinivirus has been detected in the Caribbean, outside of the continental United States. The ability of ToCV to be transmitted by four different whitefly species increases the potential for this virus to spread throughout the Caribbean Basin.
References: (1) G. C. Wisler et al. Plant Dis. 82:270, 1998. (2) G. C. Wisler et al. Phytopathology 88:402, 1998.