title: Expression of the Tomato Pto Gene in Tobacco Enhances Resistance to Pseudomonas syringae pv tabaci Expressing avrPto.
abstract: The Pto gene encodes a serine-threonine kinase that confers resistance in tomato to Pseudomonas syringae pv tomato strains expressing the avirulence gene avrPto. We examined the ability of Pto to function in tobacco, a species that is sexually incompatible with tomato. Evidence that a heterologous Pto-like signal transduction pathway is present in tobacco was suggested by the fact that tobacco line Wisconsin-38 exhibits a hypersensitive response after infection with P. syringae pv tabaci expressing avrPto. We introduced a Pto transgene into cultivar Wisconsin-38 and assessed the ability of transformed plants to further inhibit growth of the P. s. tabaci strain expressing avrPto. The Pto-transformed tobacco plants exhibited a significant increase in resistance to the avirulent P. s. tabaci strain compared with wild-type tobacco as indicated by (1) more rapid development of a hypersensitive resistance response at high inoculum concentrations (108 colony-forming units per mL); (2) lessened severity of disease symptoms at moderate inoculum concentrations (106 and 107 colony-forming units per mL); and (3) reduced growth of avirulent P. s. tabaci in inoculated leaves. The results indicate that essential components of a Pto-mediated signal transduction pathway are conserved in tobacco and should prompt examination of resistance gene function across even broader taxonomic distances.
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, Indiana 47907-1150.
authors.forename: R. L.
authors.initials: RL
authors.lastname: Thilmony
authors.forename: Z.
authors.initials: Z
authors.lastname: Chen
authors.forename: R. A.
authors.initials: RA
authors.lastname: Bressan
authors.forename: G. B.
authors.initials: GB
authors.lastname: Martin