Plant growth promotion and induced systemic resistance in tobacco by volatiles from Pseudomonas fluorscens SS101

Plant growth-promoting rhizobacterium (PGPR) can induce various metabolic changes in plants that lead to changes in growth, development and resistance to plant pathogens. Here we show that Pseudomonas fluorscens strain SS101 (Pf.SS101) protects tobacco plants (Nictotiana tobacum L.) from infection by soft rot pathogen Pectobacterim carotovorum SCC1 through induction of systemic resistance (ISR). Strain Pf.SS101 also enhanced biomass of tobacco plants when grown under in vitro conditions using I-plate assay. To determine whether the volatiles from Pf.SS101 are involved in ISR and/or plant growth promotion of tobacco, we performed solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) analysis and bioassays. SPME-GC-MS revealed that Pf.SS101 released at least 12 different volatiles with 13-tetradecadien-1-ol being highly represented. When compared to water-treated control, Pf.SS101 grown on different media showed greater appearance of plant growth promotion and ISR against soft rot in tobacco. However, among various media tested, for the growth of Pf.SS101 to release volatiles for growth promotion and ISR activity, potato dextrose agar (PDA) and King‘s B agar (KBA) media were found to have greater effect on plant growth promotion, while nutrient agar (NA) and KBA were found to have greater effect on ISR activity when compared to tryptic soy agar (TSA), PDA, and luria bertani agar (LBA) media.