Root Rot Disease Biocontrol and Microbiome Community Modulation by <i>Streptomyces</i> Strains in Soybean

Traditionally, phytopathogenic fungi control strategies rely primarily upon chemical fungicides, but fungicide resistance pathogen strains have appeared in the fields. Therefore, biocontrol approaches highlighted with sustainable agriculture aspects, especially the genus <i>Streptomyces</i>, are known to suppress numerous plant diseases. <i>Streptomyces bacillaris</i> S8 was isolated from turfgrass rhizosphere, and <i>Streptomyces globisporus</i> SP6C4 was obtained from strawberry pollen. Both strains showed excellent antifungal and antibacterial activities and suppressed various plant diseases <i>in vitro</i>. However, beneficial microorganisms are rarely studied and introduced to another effect on microbial communities when incompatible with the host. The present study aims to assess the potential of effective control of plant diseases by both strains in new crops and to assess the impact of endogenous microbiota. Various diseases pose significant concerns in soybean production, leading to substantial grain yield and quality losses. Root rot caused by <i>Fusarium</i> spp. is known to be the most problematic disease in the soybean cropping system. In the results, <i>S. globisporus</i> SP6C4 and <i>S. bacillaris</i> S8 showed antifungal activity against soybean root rot pathogen, but strain S8 had less than SP6C4. The strain SP6C4 played a role as hub-taxa in the early stage, and the strain S8 was a modulator in microbial communities. Our results demonstrate the antifungal activity of <i>S. globisporus</i> SP6C4 and <i>S. bacillaris</i> S8, which can be expected to grow and reduce the disease of soybeans. The S8 and SP6C4 can also modify the plant microbiota which may open a new dimension of crop microbiome research.