Genetic Engineering of Potyvirus Resistance Using Constructs Derived from the Zucchini Yellow Mosaic Virus Coat Protein Gene. Guowei Fang. Department of Horticulture, Michigan State University, East Lansing, 48824 U.S.A. Rebecca Grumet. Department of Horticulture, Michigan State University, East Lansing, 48824 U.S.A. MPMI 6:358-367. Accepted 26 January 1993. Copyright 1993 The American Phytopathological Society.

Three versions of the zucchini yellow mosaic virus (ZYMV) coat protein gene were engineered for expression in plants: the full-length coat protein sequence, the conserved core portion of the gene, and an antisense version. These constructs were introduced into muskmelon (Cucumis melo) and tobacco plants (Nicotiana tabacum) via Agrobacterium tumefaciens-mediated transformation; gene expression was verified by Northern and Western analysis. Transgenic R₀ and R₁ muskmelon plants expressing the full-length coat protein gene exhibited apparent immunity to ZYMV infection: There was a lack of symptom development during a 3-mo observation period and no measurable virus accumulation as determined by ELISA. Melon plants expressing the core or antisense constructs showed a several-day delay of systemic symptom development and reduction in virus titer. Furthermore, transgenic R₁ tobacco plants expressing the full-length coat protein, core, or anti-sense constructs of ZYMV, a nonpathogen of tobacco, showed a short delay in symptom development and reduced virus titer when inoculated with the heterologous poty-viruses, potato virus Y, and tobacco etch virus. The transgenic tobacco plants were not protected against the nonpotyvirus, tobacco mosaic virus.