Trichoderma koningiopsis controls Fusarium oxysporum causing damping-off in Pinus massoniana seedlings by regulating active oxygen metabolism, osmotic potential, and the rhizosphere microbiome

Abstract

Masson pine (Pinus massoniana Lamb) is a high-economic-value tree species in southern China. However, P. massoniana seedlings in nurseries are damaged by damping-off disease caused by Fusarium oxysporum. Although Trichoderma spp. are used to control pathogens, the biocontrol mechanism by which Trichoderma koningiopsis suppresses damping-off disease remains unclear. In the present study, T. koningiopsis inoculation significantly decreased damping-off symptoms in P. massoniana and promoted seedling growth. Physiological and biochemical measurements revealed that T. koningiopsis controlled F. oxysporum by reducing reactive oxygen species, lowering lipid peroxidation and cell death, increasing osmolyte content, stimulating the activities of antioxidant enzymes, and increasing soil fertility. Illumina MiSeq sequencing revealed that T. koningiopsis increased plant growth-promoting Acidobacteria (19.9%) and decreased F. oxysporum occurrence by 92.0%. In addition, plant growth-promoting rhizobacteria (Pseudomonas, Bradyrhizobium, and Enterobacter) and ectomycorrhizal fungi (Clavulina, Pezoloma, Sphaerosporella, and Tomentella) were significantly enriched in rhizosphere soil following T. koningiopsis treatment. Thus, T. koningiopsis is a potential biocontrol agent for damping-off disease caused by F. oxysporum that also promotes P. massoniana seedling growth.