First Report of an Epidemic in Tomato Caused by Two Whitefly-Transmitted Geminiviruses in Puerto Rico. J. K. Brown, Department of Plant Sciences, University of Arizona, Tucson 85721 . J. Bird, College of Agricultural Sciences, University of Puerto Rico, Rio Piedras 00928 G. Banks, Department of Plant Sciences, University of Arizona, Tucson 85721 M. Sosa, College of Agricultural Sciences, University of Puerto Rico, Rio Piedras 00928 K. Kiesler, Department of Plant Sciences, University of Arizona, Tucson 85721 and I. Cabrera and G. Fornaris, College of Agricultural Sciences, University of Puerto Rico, Rio Piedras 00928. Plant Dis. 79:1250. Accepted 26 September 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-1250A.
Whitefly-infested commercial tomato fields exhibited nearly 100% viruslike disease symptoms in four locations in Puerto Rico (PR) during the spring of 1995. A small proportion of plants (<10%) exhibited a yellow foliar mottle, but the predominant symptom type was severe leaf curl, stunting, and cracking of tomato fruits. Reduced quality of tomato fruit and up to 80% yield loss occurred. The agent(s) from tomato plants expressing the mottle and the predominant, severe symptom types were transmissible from tomato to tomato or to tobacco, by interspecific grafting and by the whitefly vector, the B biotype of Bemisia tabaci (Gennadius) (also known as B. argentifoli). The severe isolate was not transmissible to Physalis floridana or bean (Phaseolus vulgaris) using the whitefly vector. Symptoms induced upon back-inoculation of tomato seedlings from symptomatic, experimentally inoculated tomato (or tobacco plants) were like the mottle or severe leaf curl symptoms observed in field-infected tomato plants, respectively. Polymerase chain reaction (PCR) primers that specifically amplify the core region of the coat protein (core Cp) gene between nucleotides 514 and 1048 of the A component of whitefly-transmitted (WFT) geminiviruses (gv) [primers: pAV514 = GCCC(W)TGTA(Y)AG(R)AAGCC(M)AG/pAC1048 = GG(R)TT(D)GA (R)GCATG(H)GTAACATG] yielded an expected 550-bp PCR product from field samples exhibiting either the yellow mottle or severe leaf curl symptom types, and from tomato plants experimentally inoculated with the isolates, either by grafting or by the whitefly vector. No virus-specific fragments were amplified from greenhouse-grown healthy tomato controls. Gv PCR fragments were directly sequenced to yield 470 to 490 bp. Core Cp DNA sequences were aligned pairwise (BESTFIT, GCG) with analogous sequences of several subgroup III gv’s that infect Solanaceous hosts: chino del tomate, pepper hausteco, pepper mild tigre, serrano golden mosaic, Sinaloa tomato leaf curl, tomato golden mosaic, tomato mottle and Texas pepper gv’s, and several TYLCV strains. The gv causing the yellow mottle symptom was 99% identical to tomato mottle gv (ToMV) from Florida, whereas the sequence of the severe isolate ranged between 87 and 94% in similarity with candidate bipartite gv’s, and showed less than 80% similarity to three TYLCV strains. A second set of PCR primers used to distinguish between several monopartite and bipartite gv’s (J. K. Brown, unpublished data D. P. Maxwell, personal communication) indicated a bipartite genome was associated with both symptom types. From these data, we conclude that this is the first report of ToMV in PR, and that the severe symptom phenotype is caused by a previously uncharacterized, bipartite, New World WFT gv that is thought to be indigenous to PR.