Plant growth promotion due to rhizobacterial volatiles – An effect of CO2?

Serratia odorifera, an antagonistic rhizobacterium, emits a diverse and complex bouquet of volatiles. Three different in vitro experimental culture systems indicated that these volatiles promote the growth of Arabidopsis thaliana. CO2 trapping and significant rise of CO2 levels (390–3000 ppm CO2 within 24 h) due to bacterial growth in sealed Petri dishes verified the enhanced effects of rhizobacterial CO2 on A. thaliana’s growth. In contrast, open cocultivations abrogated growth promotion, and inhibitory effects come to the fore at ambient CO2 concentrations.