Involvement of Jasmonic Acid in the Induced Systemic Resistance of Tomato against Ralstonia syzigiisub sp. indonesiensis by Indigenous Endophyte Bacteria

Abstract

Abstract Endophyte bacteria colonize plant roots and exert a beneficial effect on plant growth are well known for their potential to reduce plant pathogen populations in the soil, thereby suppressing diseases. Elucidation of signaling pathways controlling disease resistance is a major objective in research on plant-pathogen interactions. It has been suggested that jasmonic acid (JA) could be an integral part of a general signal transduction system regulating inducible defense genes in plants. Recent studies had shown that Endophyte bacteria could elicited induce systemic resistance (ISR) of plants by jasmonic acid pathway. This research purposed to study the involvement of JA in ISR of tomato plants against Ralstonia syzigiisubsp. Indonesiensis by indigenous endophyte bacteria. This research assayed the JA contained in the leaves and roots of tomato plants that treated with indigenous endophyte bacteria (seed and seedlings treatment) and inoculated with R. syzigiisub sp. Indonesiensis with Gas Chromatography-Mass Spectrophotometry (GC-MS) in interval between 0 to 30 days after pathogen innoculation. Results shown that all selected indigenous endophyte bacteria can suppress R. syzigiisub sp. Indonesiensis attack and increase JA contained in leaves and roots of tomato significantly until 12 days after pathogen innoculations. Strain Bacillus cereus EPL1.1.3 and Serratianematodiphila TLE1.1 respectively had the highest JA activivity both in roots and leaves of tomato. This indicated that one of the selected indigenous endophyte bacteria abilities to suppress pathogens attack mechanism related to JA pathway.