Abstract:

To study the endophytic antagonistic strains, six medicinal plants, including Glechoma longituba, Conyza canadensis, Ranunculus japonicus, Gynura segetum, Thalictrum aquilegifolium and Chelidonium majus, were used as plant materials to extract and isolate the strains, and the antibacterial activities were tested. Three strains with high antibacterial activity were selected for molecular identification through 18S rDNA sequencing and phylogenetic tree construction. The results showed that all the six medicinal plants contained endophytic fungi, and 5 endophytic fungi were isolated from Glechoma longituba, 2 from Conyza canadensis, 4 from Ranunculus japonicus, 2 from Gynura segetum, 1 from Thalictrum aquilegifolium, and 2 from Chelidonium majus. Seven strains of antagonistic bacteria were obtained, which were LJ3, MJ2, MY1, TJ1, TJ2, J1 and BY1. MJ2 had the highest inhibitory rate of 56.47% against Alternaria alternata. MY1 and BY1 were identified as Clonostachys rosea, and TJ2 as a strain of Fusarium. It is proved that the endophytic bacteria have obvious antagonistic effect on Alternaria alternata and could be used for biological control of plant diseases.

Key words: medicinal plants, endophytic fungi, isolation and culture, ITS, identification, antagonism