Retraction

PLANT BIOLOGY. For the article “Suppression of pathogen-inducible NO synthase (iNOS) activity in tomato increases susceptibility to Pseudomonas syringae,” by Meena R. Chandok, Sophia K. Ekengren, Gregory B. Martin, and Daniel F. Klessig, which appeared in issue 21, May 25, 2004, of Proc. Natl. Acad. Sci. USA (101, 8239–8244; first published May 14, 2004; 10.1073/pnas.0402344101), the undersigned authors note the following retraction. The paper is an extension of a recently retracted paper [Chandok, M. R., Ytterberg, A. J., van Wijk, K. J., and Klessig, D. F. (2003) Cell 113, 469–482], which reported that the pathogen-inducible NO synthase (iNOS) in plants is a variant form of the P subunit of the glycine decarboxylase complex. Since publication of the Cell paper, members of the Klessig laboratory have been unable to repeat the results with recombinant variant P. Therefore, the rationale no longer exists for silencing varP in tomato and examining the effects on host defense as the authors reported in the PNAS paper. For this reason and because the undersigned authors are no longer confident in much of the data in Figs. 1, 3, and 4, they hereby retract their PNAS article. The data showing that virus-induced silencing of varP increases susceptibility to Pseudomonas syringae pv. tomato were generated by S. K. Ekengren and G. B. Martin and are not in question (Figs. 2 and 3A). However, the observed increase in disease susceptibility of varP-silenced plants was likely due to pleiotropic effects on plant defenses as a result of the decrease in glycine decarboxylase. M. R. Chandok has not approved this assessment or the retractions. The undersigned authors deeply regret this incident and sincerely apologize.