Phenotypic and molecular characterization of resistance induction by single and combined application of chitosan and silicon in tomato against Ralstonia solanacearum

Silicon (Si) and chitosan (Chi) treatments induced resistance in tomato against bacterial wilt caused by Ralstonia solanacearum. Gene expression analysis conducted at 72 h post inoculation via TOM2 microarray revealed regulation of 204 and 126 genes in genotypes King Kong 2 and L390, respectively, with their majority classified into the categories defense-related, signal transduction and transcription. In the microarrays, translationally-controlled tumor protein homolog involved in stress reaction of plants, the defense genes chitinases and peroxidases were highly up-regulated in combined Si and Chi treatment. Bacterial wilt incidence was reduced by 40% and 56.6% in Si and Chi treatment, respectively, in King Kong 2, and by 26.6% and 33.3% in Si and Chi treatment, respectively, in L390, and by 74.7% in King Kong 2 and 46.6% in L390 after combined application of Si and Chi. Evidence of their synergistic effects is reported.

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► Silicon and chitosan induced resistance in tomato against Ralstonia solanacearum.
► Their application triggered expression of mainly defense-related genes.
► Resistance was manifested in bacteria reduction in the plant tissue and reduced plant wilting.
► When applied together, their effect against the pathogen was synergistic.