Nonhost resistance is a type of broad-spectrum resistance exhibited by a given plant species to most strains of a pathogen which are generally pathogenic to other plant species. In this study, we have examined the role of tobacco SABP2 (Salicylic acid-Binding Protein 2) in nonhost resistance. SABP2, a methyl salicylate esterase is a critical component of SA-signaling pathway in tobacco plants. The transgenic tobacco SABP2-silenced lines treated with tetraFA, a known inhibitor of esterase activity of SABP2 exhibited enhanced susceptibility to nonhost pathogen, Pseudomonas syringae pv. phaseolicola compared to the control plants. The increased accumulation of SABP2 transcripts upon Psp infection supports the involvement of SABP2 in nonhost resistance. The tetra-FA treated plants also showed delayed expression of pathogenesis related-1 gene upon Psp inoculations. The expression of nonhost marker genes CDM1 and HIN1 was also monitored in tobacco plants infected with host-pathogen P.s. pv. tabaci and P.s. pv. phaseolicola. Overall, results presented in this manuscript suggest that SABP2 has a role in nonhost resistance in tobacco plants.

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