Abstract

Magnaporthe oryzae is a major hazard to the growth and yield of rice and other graminaceous crops. The rice endophyte Streptomyces hygroscopicus OsiSh-2 has been reported to have a strong antagonistic effect on M. oryzae . However, the defence mechanism of OsiSh-2 against pathogens remains to be established. In this study, a combination of physiological, biochemical and label-free proteomics analyses were used to investigate the global response of OsiSh-2 to the toxins of M. oryzae (Mo-toxins). When exposed to Mo-toxins, OsiSh-2 regulated its growth rate to get rapid transition to the stationary growth phase where stronger antibiotic activity was achieved. Additionally, OsiSh-2 triggered reactive oxygen species (ROS) generation, hydrolase activity and biofilm formation in response to Mo-toxin stress. Finally, proteomic profiling confirmed that OsiSh-2 possesses the following sophisticated coping strategies against Mo-toxins: (1) sensing and transmittance of Mo-toxin signals by signal-transmitting proteins; (2) damaging the toxicity of M. oryzae by hydrolytic enzymes and other secondary products; and (3) guaranteeing the secretion and function of proteins by proteases and protein isomerases . Our research may promote the understanding of the interaction between antagonistic microbes and further broaden the scope of utilizing endophytic Streptomyces for biological control.