Employs Diverse Genes for Inhibiting Hypha Growth and Spore Germination of Soybean Fungal Pathogens.

strain C3 (LeC3) is a potential biocontrol agent for plant diseases caused by fungi and oomycetes. Understanding the interaction between LeC3 and soybean pathogens at the molecular level could help improve its biocontrol efficacy. In this study, we obtained mutants with decreased abilities in inhibiting hypha growth of the white mold pathogen . Insertion sites for 50 mutants, which no longer inhibited hypha growth in dual cultural assay, were determined and seven mutants were selected for further characterization. These seven mutants also completely lost their abilities in suppressing spore germination of , the causal agent of soybean sudden death syndrome. Furthermore, mutation of the seven genes, which encode diguanylate cyclase, transcriptional regulators from the TetR family, hemolysin III family channel protein, type IV secretion system VirB10 protein, phenol hydroxylase, and phosphoadenosine phosphosulfate reductase, respectively, led to reduced production or secretion of four extracellular enzymes and heat-stable antifungal factor (HSAF). These results suggest that these seven genes play important roles in in suppressing hypha growth and spore germination of fungal pathogens, probably by influencing production or secretion of extracellular enzymes and HSAF.