Correlation analysis between diversity of arbuscular mycorrhizal fungi in roots and soil physicochemical properties of Panax notoginseng(Burk.)F. H. Chen at different ages

【Objective】To clarify the relationship between arbuscular mycorrhizal fungi (AMF)diversity,community structure and physicochemical properties of rhizosphere soil of Panax notoginseng(Burk.) F. H. Chen in different years, and provide reference for the application of AMF in alleviating the obstacles of continuous cropping of P. notoginseng.【Method】In this study,the root system and rhizosphere soil of P. notoginseng aged one,two and three year-old were used as experimental materials. The AMF infection rate of root system was observed by using the microscopic morphology observation method. The differences of AMF diversity and community structure of the P. notoginseng root system were analyzed using Illumina high-throughput sequencing. Pearson correlation coefficient method was used to reveal the correlation between relative abundance of P. notoginseng roots AMF diversity and physicochemical properties of rhizosphere soil.【Result】The results showed that the AMF infection rates of P. notoginseng root ranged from 83% to 95%. With the extension of planting years,the contents of alkali-hydrolyzed nitrogen,total nitrogen and total phosphorus in rhizosphere soil gradually decreased,the contents of available phosphorus and available potassium first decreased and then increased, and the soil acidification was strengthened. A total of 55 OTUs were detected in the root system of P. notoginseng by highthroughput sequencing. Excluding the unclassified groups,these OTUs belonged to 19 species,4 orders,6 families,7 genera of Glomeromycetes,and Glomus accounted for the highest proportion(45.30%). The results of the diversity analysis showed that the three-year-old P. notoginseng had the least number of root OTUs and the lowest diversity and richness compared to the one-year-old and two-year-old P. notoginseng. Partial least squares discriminant analysis(PLS-DA) showed that the AMF community structure of P. notoginseng root system was different in different years samples,and Glomus was the dominant genus of one-year-old and three-year-old root system(proportions were 32.31% and 53.68%), while Paraglomus was the dominant genus of two-year-old root system(proportion 50.39%). The results of correlation analysis showed that the ACE and Chao indexes of AMF of P. notoginseng root was significantly positively correlated with total phosphorus in rhizosphere soil (P<0.05),and significantly or extremely significantly(P<0.01)negatively correlated with available phosphorus and available potassium.【Conclusion】There are obvious differences in the abundance and community structure of AMF in the root system of P. notoginseng in different years. With the increase of planting years, the abundance and OTUs of AMF in the root system of P. notoginseng gradually decrease,but the relative abundance of Glomus gradually increases. In the rhizosphere soil of P. notoginseng,the contents of effective phosphorus and quickacting potassium are the main factors affecting the community structure of AMF in its root system.