Abstract: Plants are closely related to fungi, bacteria, as well as actinomycetes, constituting a coevolutionary and mutualistic system. There are globally 25 dominant genera of plant symbiotic actinomyces (PSAs), with rich species resources and wide distribution. These PSAs may colonize plant roots, stems and/or leaves to form various symbionts. PSAs can improve plant growth and development through directly or indirectly increasing nutrient and water absorption and utilization, and excretion of plant growth hormones. They can enhance plant stress resistance (such as salt and toxic heavy metal tolerance, and disease resistance) through synthesizing antibiotics and secondary metabolites. Furthermore, they could promote soil health through adjusting soil chemical and physical properties and activating soil nutrients. The development and functions of symbionts between 〖HJ*3〗plants and actinomyces are influenced and regulated by soil conditions, climate factors, geographical characters, and agricultural management strategies. The current status of PSAs application and the problems existing in the current research are also analyzed, aiming to provide theoretical basis and reference for further research and application of PSAs. PSAs are new and unexploited microbial resources with broad application prospect.

Key words: subalpine dark coniferous forest, phylogenetic structure, diameter class, community assembly, Sygera Mountains