Insights into the Defense-Related Events Occuring in Plant Cells Following Perception of Surfactin-Type Lipopeptide from Bacillus subtilis

Multiple strains of Bacillus subtilis were demonstrated to stimulate plant defense responses, and cyclic lipopeptides may be involved in the elicitation of this induced systemic resistance phenomenon. Here, we further investigated molecular events underlying the interaction between wuch lipopeptides and plant cells. Addition of surfactin but not fengycin or iturin in the micromolar range to tobacco cell suspensions induced defense-related early events such as extracellular medium alkalinization coupled with ion fluxes and reactive oxygen species production. Surfactin also stimulated the defense enzymes phenylalanine ammonia lyase and lipoxygenase and modified the pattern of phenolics produced by the elicited cells. The occurence of these surfactin-elicited early events is closely related to Ca2+ influx and dynamic changes in protein phosphorylation but is not associed with any marked phytotoxicity or adverse effect on the integrity and growth potential of the treated tobacco cells.