RESUMO
Various metabolites, including phytohormones, phytoalexins, and amino acids, take part in the plant immune system. Herein, we analyzed the effects of L-methionine (Met), a sulfur-containing amino acid, on the plant immune system in tomato. Treatment with low concentrations of Met enhanced the resistance of tomato to a broad range of diseases caused by the hemi-biotrophic bacterial pathogen Pseudomonas syringae pv. tomato (Pst) and the necrotrophic fungal pathogen Botrytis cinerea (Bc), although it did not induce the production of any antimicrobial substances against these pathogens in tomato leaf tissues. Analyses of gene expression and phytohormone accumulation indicated that Met treatment alone did not activate the defense signals mediated by salicylic acid, jasmonic acid, and ethylene. However, the salicylic acid-responsive defense gene and the jasmonic acid-responsive gene were induced more rapidly in Met-treated plants after infection with Pst and Bc, respectively. These findings suggest that low concentrations of Met have a priming effect on the phytohormone-mediated immune system in tomato.
Assuntos
Botrytis , Ciclopentanos , Regulação da Expressão Gênica de Plantas , Metionina , Doenças das Plantas , Reguladores de Crescimento de Plantas , Pseudomonas syringae , Solanum lycopersicum , Solanum lycopersicum/microbiologia , Solanum lycopersicum/imunologia , Solanum lycopersicum/genética , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/metabolismo , Metionina/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/genética , Pseudomonas syringae/patogenicidade , Ciclopentanos/farmacologia , Ciclopentanos/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Oxilipinas/farmacologia , Oxilipinas/metabolismo , Imunidade Vegetal/efeitos dos fármacos , Resistência à Doença/efeitos dos fármacos , Resistência à Doença/imunologia , Ácido Salicílico/farmacologia , Ácido Salicílico/metabolismo , Folhas de Planta/imunologia , Folhas de Planta/microbiologia , Folhas de Planta/efeitos dos fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Etilenos/metabolismoRESUMO
Systemic acquired resistance (SAR) is a potent innate immunity system in plants that is induced through the salicylic acid (SA)-mediated signaling pathway. Here, we characterized 3-chloro-1-methyl-1H-pyrazole-5-carboxylic acid (CMPA) as an effective SAR inducer in Arabidopsis. The soil drench application of CMPA enhanced a broad range of disease resistance against the bacterial pathogen Pseudomonas syringae and fungal pathogens Colletotrichum higginsianum and Botrytis cinerea in Arabidopsis, whereas CMPA did not show antibacterial activity. Foliar spraying with CMPA induced the expression of SA-responsible genes such as PR1, PR2 and PR5. The effects of CMPA on resistance against the bacterial pathogen and the expression of PR genes were observed in the SA biosynthesis mutant, however, while they were not observed in the SA-receptor-deficient npr1 mutant. Thus, these findings indicate that CMPA induces SAR by triggering the downstream signaling of SA biosynthesis in the SA-mediated signaling pathway.