Abstract
Trichoderma spp., Metarhizium spp., and Bacillus spp. are commonly used as biocontrol microorganisms domestically and internationally. However, microbial pesticides currently prepared from single living microorganisms have problems such as a short shelf life, particularly under stressful environment conditions. Secondary metabolites produced from biocontrol microorganisms are comparatively stable when used under field conditions. This study screened the optimal combination of biocontrol metabolites, referred to as TMB, composed of culture filtrates from certain isolates of Trichoderma asperellum 10264, Bacillus subtilis S4-4-10, and Metarhizium anisopliae 3.11962 (1:4:1 (v/v)). RNA-seq analysis and transmission electron microscope observations were carried out to identify the major functions of the most effective culture filtrates against Magnaporthe oryzae (the pathogen causing rice blast disease) and Chilo suppressalis (an insect pest in rice cultivation). TMB was found to disrupt the midgut subcellular structure of C. suppressalis larvae and inhibit the expression of genes related to immunity, membrane components, protein synthesis, and other functions in C. suppressalis larvae and M. oryzae, thereby interfering with their normal growth, reproduction, and infection potential in rice. In addition, TMB was also able to promote rice growth and trigger host defense responses against infections by the target pests and pathogens. In summary, TMB generated different inhibitory activities against multiple targets in C. suppressalis and M. oryzae and induced plant immunity in rice. Therefore, it can be used as a new environmentally friendly agent or alternative to control rice pests and diseases.