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Fitopatologia Brasileira

Print version ISSN 0100-4158

Abstract

CAVALCANTI, Fábio Rossi et al. Acibenzolar-S-methyl and Ecolife® in the induction of defense responses in tomato against bacterial spot (Xanthomonas vesicatoria). Fitopatol. bras. [online]. 2006, vol.31, n.4, pp. 372-380. ISSN 0100-4158.  http://dx.doi.org/10.1590/S0100-41582006000400007.

The efficacy of acibenzolar-S-methyl (ASM) and Ecolife® and the activation of some defense responses against Xanthomonas vesicatoria were investigated in the current work. Tomato plants cv. Santa Cruz Kada were sprayed with acibenzolar S-methyl (0.2 g l-1 ASM and a citric biomass formulation called Ecolife® (5 ml l-1). Plants were challenged with a virulent Xanthomonas vesicatoria isolate four days after spraying. Foliar pulverization of Ecolife® and ASM caused disease reduction of 39.2% and 47.7%, respectively. The expression of resistance induced by ASM and Ecolife® was evidenced by the increase at peroxidase (POX) and polyphenol oxidase (PPO) activities, starting in the first hours after spraying. Despite the slight decrease in phenylalanine ammonia-lyase (PAL) activity three days after spraying, plants treated with ASM or Ecolife® and inoculated with X. vesicatoria showed a slight increase in lignin deposits. The content of total soluble phenolic compounds decreased significantly at 9 and 12 days after spraying. Increased POX and PPO activities might result in lignification, which may be associated with the tomato's defense strategy against bacterial leaf spot.

Keywords : Systemic acquired resistance; peroxidase; polyphenol oxidase; phenylalanine ammonia lyase; phenolic content; lignin.

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