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Disease Note.

Evaluation of Selected Lycopersicon and Capsicum Germ Plasm for Watermelon Silver Mottle Tospovirus Resistance. S. K. Green, Asian Vegetable Research and Development Center, Shanhua, Tainan 741, Taiwan, R.O.C . J. T. Hwang, and J. C. Chou, Asian Vegetable Research and Development Center, Shanhua, Tainan 741, Taiwan, R.O.C. Plant Dis. 80:824. Accepted for publication 13 May 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0824B.

Selected Lycopersicon and Capsicum spp. germ plasm with reported resistance to Brazilian and North American isolates of tomato spotted wilt tospovirus (TSWV) were evaluated in the greenhouse for their reactions to watermelon silver mottle tospovirus (WSMV), which infects tomato and cucurbits in Taiwan (2). Symptoms on tomato induced by WSMV include yellowing and necrosis of the leaves, often in the form of rings. Infected fruit are distorted and show various types of necroses and irregular ripening. The virus was originally isolated from an infected tomato plant in Taiwan and was maintained in Nicotiana benthamiana (1). Mechanical inoculations were done on the first fully expanded leaves of 20 plants of each line to be tested. C. annuum L. 'Yolo Wonder,' highly susceptible to WSMV, was included as a positive control. Double antibody sandwich enzyme-linked immunosorbent assays (DAS ELISAs), with a WSMV polyclonal antiserum provided by G. Adam of the Federal Research Institute of Biological Sciences, BBA, Braunschweig, Germany, were done at 25 and 35 days after inoculation. Greenhouse temperatures ranged from 24 to 36C from the time of inoculation to the last ELISA. Chlorotic rings or lesions later turning necrotic were observed on inoculated as well as noninoculated leaves of L. esculenlum Mill. 'SW307' and 'Stevens,' C. chinense Jacq. PI 159236, and on the positive check. Presence of virus in uninoculated leaves was confirmed by ELISA. One line, C. chinense Jacq. PI 152225, developed necrotic rings oninoculated leaves, but did not show any systemic infection. Virus was only detected in symptomatic leaves. Another line, L. hirsutum Humb. & Bonpl. PI 247087, with no reported resistance to tospovirus but with resistance to PVY showed no symptoms at all, and virus could only be detected in the inoculated leaves of 25% of the plants. These two lines may be useful in breeding peppers and tomatoes resistant to WSMV.

References. (1) S K. Green and J. C. Chou. Plant Prot. Bull. (Taipei) 33:424, 1991. (2) S.-D. Yeh and T.-F. Chang. Phytopathology 85:58, 1995.