Cyclic Dipeptides from BS07 Require Key Components of Plant Immunity to Induce Disease Resistance in against Infection.

Cyclic dipeptides (CDPs) are one of the simplest compounds produced by living organisms. Plant-growth promoting rhizobacteria (PGPRs) also produce CDPs that can induce disease resistance. strain BS07 producing various CDPs has been evaluated as a potential biocontrol agent against multiple plant pathogens in chili pepper. However, plant signal pathway triggered by CDPs has not been fully elucidated yet. Here we introduce four CDPs, cyclo(Gly-L-Pro) previously identified from sp., and cyclo(L-Ala-L-Ile), cyclo(L-Ala-L-Leu), and cyclo(LLeu-L-Pro) identified from BS07, which induce disease resistance in against infection. The CDPs do not directly inhibit fungal and oomycete growth . These CDPs require , , and important for salicylic acid-dependent defense to induce resistance. On the other hand, regulators involved in jasmonate-dependent event, such as , , and , are necessary to the CDP-induced resistance. Furthermore, treatment of these CDPs primes plants to rapidly express at early infection phase. Taken together, we propose that these CDPs from PGPR strains accelerate activation of jasmonate-related signaling pathway during infection.