Diversity and Community Structure of Arbuscular Mycorrhizal Fungi (AMF) in the Rhizospheric Soil of Panax notoginseng in Different Ages

To clarify the influence of planting year on the characteristics of colonization of the roots of Panax notoginseng by arbuscular mycorrhizal fungi (AMF) and rhizospheric soil AMF diversity. In this study, the roots and rhizospheric soil of one-, two- and three-year-old Panax notoginseng were used as experimental materials, and the level of AMF colonization and the density of spores in the rhizospheric soil of Panax notoginseng roots were determined by microscopic morphological observation. The diversity and community structure of AMF in the rhizospheric soil of Panax notoginseng were analyzed by Illumina high-throughput sequencing technology, and the influence of rhizospheric soil of Panax notoginseng physicochemical properties on the diversity and relative abundance of AMF was further revealed by the application of redundancy analysis and a Spearman correlation coefficient. In this study, 99 AMF OTUs were detected in the rhizospheric soil of Panax notoginseng, exclusion of non-categorization, which belonged to one class, four orders, six families and seven genera. Among them, the number of AMF OTUs in the rhizospheric soil of three-year-old Panax notoginseng was significantly higher than that in the rhizospheric soils of one- and two-year-old Panax notoginseng. Although there was no significant difference in the parameters of AMF colonization in the roots of Panax notoginseng of different ages, the diversity of AMF in the rhizospheric soil tended to increase in parallel with the planting years. Glomus was the dominant genus of AMF in the rhizospheric soils of Panax notoginseng of different ages, and its abundance increased with the increase of planting years. A partial least squares-discriminant analysis showed that continuous cropping could significantly change the community structure of AMF in the rhizospheric soil of Panax notoginseng. The results of a correlation analysis showed that in the rhizospheric soil of Panax notoginseng, the organic matter content negatively correlated with AMF diversity and abundance and significantly positively correlated with the abundance of Glomus. Compared with other years, the species abundance of AMF in the rhizospheric soil of three-year-old Panax notoginseng increased, and the community structure changed significantly.