Identification and characterization of a cyclic lipopeptide iturin A from a marine-derived Bacillus velezensis 11-5 as a fungicidal agent to Magnaporthe oryzae in rice

Abstract

Magnaporthe oryzae is an important rice pathogen globally. However, plant beneficial microbes and their secondary metabolites to control blast disease in rice are poorly understood. In the present study, a marine-derived Bacillus velezensis 11-5 has been characterized as an antagonist against an isolate of Magnaporthe oryzae, the causal agent of rice blast disease. A cyclic lipopeptide (CLP) iturin A has been identified from the fermentation broth of B. velezensis 11-5 by nuclear magnetic resonance spectroscopy and mass spectrometry. In addition, the in vitro and in planta biocontrol activities of CLP iturin A were evaluated in the further study, respectively. The results revealed that iturin A shows significant activity on the conidia germination and the relative appressoria formation rate of M. oryzae at the concentrations of 10 and 50 µM for 12 h and for 24 h, respectively. In addition, CLP iturin A shows the significant activity to control M. oryzae in rice plants when the concentration of the compound is higher than 10 µM. Taken all results together, this study shows that B. velezensis 11-5 has the possibility to be developed as a biopesticide to control rice blast disease in rice plants, and for the first time, this study shows a CLP iturin A produced by B. velezensis 11-5 is an agrochemical to control rice blast disease both in vitro and in rice. And therefore, the results provide information on the application of B. velezensis 11-5 and its CLP iturin A as potential biopesticides to control blast disease in rice for agricultural practice.