Identification, Antimicrobial and Plant Growth Promoting Activities of Endophytic Fungi Associated with Cynomorium songaricum Rupr., a Traditional Medicinal Plant in Mongolia

Abstract

Endophytic fungi colonize the inner tissues and provide direct and indirect benefits to plants. Although Mongolia is rich in medicinal plants, due to climatic and anthropogenic reasons, the resources are being depleted, and many species are under threat of gradual extinction, while the endophytic fungi of Mongolian plants are largely unknown. In this study, a total of 24 culturable endophytic fungal strains were isolated from Cynomorium songaricum (Rupr.), a medicinal and vulnerable plant species of Mongolia. Based on the morphological characteristics and the sequences of the rDNA internal transcribed spacer (ITS) region, the isolates were identified into six genera: Fusarium (8), Clonostachys (7), Penicillium (6), Alternaria (1), Aspergillus (1), and Madurella (1). The antimicrobial activity was assessed by the agar-diffusion method, revealing that 15 strains were able to inhibit the growth of at least one of the test organisms. Among them, 1 strain showed inhibitory activity against Escherichia coli, 12 against Bacillus subtilis, 13 against Staphylococcus aureus, and 8 against Aspergillus niger, respectively. The ability to solubilize complex phosphorus and zinc minerals was observed in 3 and 21 strains, respectively, and the production of indole-3-acetic acid (IAA) was detected in nine strains in the presence of tryptophan. Our study provides the first insight into the cultivable endophytic fungal composition of C. songaricum, parasitizing the roots of Nitraria sibirica growing in the Gobi Desert of Mongolia. The resulting fungi, which have antimicrobial and plant growth-promoting properties, were preserved in the national culture collection and can be used to further exploit their biotechnological potential, as well as for the propagation of endangered and vulnerable medicinal plants.