Plant growth-promoting Bacillus subtilis strain as potential inducer of systemic resistance in tomato against Fusarium wilt.

摘要

Bacillus subtilis strain FZB-G was tested for its ability to produce probiotic substances and induce systemic resistance in tomato against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) causing wilt disease. Culture filtrate collected from thetransition growth phase (10-20 h post-inoculation) of bacterial strain FZB-G induced systemic resistance in tomato (cv. Harzglut) seedlings against FORL, besides promoting the root growth of seedlings. Bacterial culture filtrate from the stationary growth phase (72 h post-inoculation) was highly fungitoxic to FORL, however, it did not induce systemic resistance in tomato seedlings against FORL. On fractionation of culture filtrate from the transition phase, one of its fractions (Tr-C) stimulated root growth and induced systemic resistance in tomato seedlings against Fusarium wilt. Upon bioassay with the plant-pathogen (tomato-FORL) system, this fraction Tr-C was found to behave more like an auxin precursor, indole-3-pyruvic acid, in induction of systemic resistance and stimulation of root growth. Thus, it indicates that fraction Tr-C contains an elicitor resembling a precursor of phytohormones which might be involved in signal triggering and transduction, or in defence gene activation for the production of biochemical compounds associated with host defence.