Role of cyclic lipopeptides produced by Bacillus subtilis in mounting induced immunity in rice (Oryza sativa L.)

• Bacillus subtilis BBG111 triggers ISR in rice against R. solani.
• BBG111 triggers jasmonate, ethylene, auxin and abscisic acid-dependent defenses.
• BBG111 boosts PAMP-triggered immunity.
• Cyclic lipopeptides are essential determinants of BBG111-induced immunity.

In this study, we demonstrate the potential of Bacillus subtilis BBG111 to trigger ISR in rice (Oryza sativa L.) against Rhizoctonia solani, while there was no effect against Magnaporthe oryzae. We show that plant recognition of BBG111 induces jasmonic acid (JA) and ethylene (ET) as well as abscisic acid (ABA) and auxin signaling. In addition, B. subtilis supernatants also boosted immune responses triggered by chitin, suggesting that BBG111 triggers ISR at least in part by reinforcing basal plant defense responses. Finally, our results reveal an indispensable role of the BBG111 cyclic lipopeptides, fengycin and surfactin, in the induced defense state.