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Molecular Plant Pathology

Field Resistance of Transgenic Tomatoes Expressing the Tobacco Mosaic Virus or Tomato Mosaic Virus Coat Protein Genes. Patricia R. Sanders, Plant Sciences Division, Monsanto Company, 700 Chesterfield Village Parkway, St. Louis, MO 63198; Bernie Sammons, Wojciech Kaniewski, Lisa Haley, Jeanne Layton, Brad J. LaVallee, Xavier Delannay, and Nilgun E. Tumer. Plant Sciences Division, Monsanto Company, 700 Chesterfield Village Parkway, St. Louis, MO 63198. Phytopathology 82:683-690. Accepted for publication 21 January 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-683.

Under field conditions, transgenic tomato plants that express the coat protein (CP) gene of common (U1) strain of tobacco mosaic virus (TMV) showed a high degree of resistance to the U1 strain and to a more severe strain of TMV, PV230. Tomato fruit yields of inoculated control plants decreased 20% with U1 and 69% with PV230, whereas the CP+ line did not show any yield reduction after inoculation with U1 or PV230. In contrast, tomato plants expressing TMV CP showed either a low level of resistance or no resistance to several different tomato mosaic virus (ToMV) strains in the field. A ToMV CP gene was cloned from an isolate obtained from commercially grown tomatoes in Florida. Nucleotide sequence analysis showed that it was 88% homologous to TMV U1 strain at the amino acid level. Transgenic tomato plants expressing the ToMV CP showed a high level of resistance to ToMV in the field. These results demonstrate that although TMV and ToMV CP sequences are highly homologous, ToMV CP gene is more effective in control of ToMV in field-grown tomatoes than is the TMV CP gene.