Paenibacillus terrae NK3-4: A potential biocontrol agent that produces β-1,3-glucanase

Abstract

Biocontrol has broad application prospects, and developing new microbial strains as potential biocontrol agents is a major task. Paenibacillus terrae strain NK3-4 has the potential for use as a biocontrol agent. To characterize the potential biocontrol capacity of this strain, we evaluated its antagonism against pathogens of rice blast (Magnaporthe oryzae), corn spot disease (Exserohilum turcicum), soybean bacterial spot disease (Xanthomonas campestris pv. glycines), and rice sheath blight disease (Rhizoctonia solani), we also evaluated its effect on the development of rice blast disease in greenhouse and field trials. Strain NK3-4 exhibited distinct antagonism against M. oryzae and the other tested plant pathogens. An antifungal protein component that was able to trigger plant immune responses was isolated from the culture supernatant of strain NK3-4, and was identified as a β-1,3-glucanase (designated as PteNI). Strain NK3-4 controlled rice blast development in a greenhouse (prevention efficacy: 90.3%) and under field conditions (prevention efficacy: 35.8% and 41.3% after 7 and 14 days of treatment, respectively, in Jiamusi; 23.0% and 31.4% after 7 and 14 days of treatment, respectively, at Qixing Farm). In conclusion, P. terrae NK3-4 is a promising biocontrol agent against rice blast and other plant diseases. The antifungal activities of this strain are likely due, at least partially, to the β-1,3-glucanase PteNI.