Tobacco Mosaic Virus Elicitor Coat Protein Genes Produce a Hypersensitive Phenotype in Transgenic Nicotiana sylvestris Plants. James N. Culver. Department of Plant Pathology, University of California, Riverside 92521 U.S.A. William O. Dawson. Department of Plant Pathology, University of California, Riverside 92521 U.S.A. MPMI 4:458-463. Accepted 13 June 1991. Copyright 1991 The American Phytopathological Society.

The N’gene hypersensitive response (HR) in Nicotiana sylvestris is elicited during virus replication by the coat proteins of specific tobacco mosaic virus (TMV) mutants. In this study, both elicitor and nonelicitor coat protein open reading frames, under the control of the cauliflower mosaic virus 35S promoter, were integrated into the genome of N. sylvestris. Transgenic plants expressing a nonelicitor coat protein had a phenotype indistinguishable from nontransformed control plants. Transgenic plants expressing elicitor coat proteins displayed reduced growth and chlorosis and developed necrotic patches that eventually coalesced and collapsed entire leaves. This necrotic response appeared earlier and was more severe in transgenic plants expressing a strong elicitor coat protein than in plants expressing a weak elicitor coat protein. This demonstrates that expression of elicitor coat proteins independently of viral replication can induce the HR in N. sylvestris.