Paenibacillus polymyxa EP-4 can effectively control southern corn leaf blight and affect the selectivity of...

Southern corn leaf blight (SCLB) and Spodoptera frugiperda pose serious threats to corn yield. In recent years, an increasing number of studies have investigated biological control agents to control plant diseases and insect pests. However, research on the use of one biocontrol bacterium to control plant diseases and insect pests simultaneously is very limited. In this study, the bacterium EP-4, which can significantly inhibit the growth of Bipolaris maydis, was identified as Paenibacillus polymyxa. EP-4 metabolites inhibited hyphal growth, caused hyphal deformities, significantly reduced the spore germination of B. maydis, and damaged cell membranes, leading to DNA leakage. In the greenhouse, EP-4 significantly reduced the disease index of SCLB and the feeding and oviposition preferences of S. frugiperda to corn. Metabolite analysis revealed that inoculation with B. maydis and S. frugiperda after EP-4 pretreatment affected the production of corn resistance-related substances such as brassinolide, quercetin, 2-undecanone and naringin. Metagenomic analysis revealed that EP-4 pretreatment and subsequent inoculation with pests and diseases could induce the recruitment of Pseudomonas, Burkholderia, Azotobacter and Mesorhizobium in corn. EP-4 could significantly reduce the occurrence of SCLB and significantly affect the feeding and oviposition of S. frugiperda on corn. The mechanism of action of EP-4 on pests and diseases has been shown to differ. This strain has great application potential in corn.