Isolation and identification of phyllosphere microbiome of Panax notoginseng（Burk.） F. H. Chen and its biocontrol functions

【Objective】The purpose of the study was to isolate and screen biocontrol strains from Panax notoginseng(Burk.) F. H. Chen phyllosphere with strong inhibition effect against black spot disease of P. notoginseng leaves, in order to provide microbial resources for the development of safe and efficient biocontrol fungicides,as well as to provide reference for the ecological management of diseases affecting Chinese medicinal materials. 【Method】Cultivable phyllosphere microbiomes were isolated from healthy one-year-old P. notoginseng leaves using serial dilution method. The antagonistic effects of the isolated strains against Alternaria panax strain SL17, a pathogen causing black spot disease on P. notoginseng leaves, were evaluated using plate confrontation method. Phyllosphere microbiome strains with biocontrol effects against A. panax were screened. The active strains were classified and identified by ITS and 16S rDNA sequencing, and the strains with the best inhibition effects were further selected for the determination of broad-spectrum inhibition ability.【Result】A total of 125 isolates were isolated and purified from healthy P. notoginseng phyllosphere, from which 50 antagonistic strains with obvious inhibition effects against A. panax were obtained using plate confrontation method, including 26 fungal strains and 24 bacterial strains. Among the 26 antagonistic fungi, two P. notoginseng leaf endophytic fungal strains NZ-14 and NZ-23 showed the best inhibitory effects, of which Trichoderma koningii NZ-14 could completely inhibit the mycelial growth of A. panax with an inhibition rate of 100.00%. Among the 24 antagonistic bacterial isolates, two strains of P. notoginseng leaf endophytic bacteria NX-20 and NX-23 had the best inhibition effect, with Bacillus subtilis NX-20 having an inhibition rate of 71.13% against A. panax. The results of the inhibitory activity assays of the phyllosphere antagonists against the main fungal pathogens of P. notoginseng showed that the strains NZ-14, NZ-23, NX-20and NX-23 had good inhibition activity against Mycocentrospora acerina strain DMS5, Fusarium solani strain F3, and Cylindrocarpon destructans strain RS006, with inhibition rates ranging from 39.26% to 78.97%. 【Conclusion】There are many microbiomes in the phyllosphere of P. notoginseng with potential inhibition activity, among which the two Trichoderma strains NZ-14 and NZ-23 and the two Bacillus strains NX-20 and NX-23 have the best inhibition effects and strong inhibitory activity against the main fungal pathogens of P. notoginseng leaves and roots, and can be used as microbial resources for biological control of P. notoginseng diseases.