Effects of plum tree intercropping on the growth and rhizosphere soil microorganisms of Polygonatum cyrtonema Hua. based on metagenomics

Background: To investigate the variations in rhizosphere-associated microorganisms, rhizosphere soil nutrients, secondary metabolites, relative expression of the key enzyme genes involved in polysaccharide synthesis, and phenotype in the monocropping and intercropping pattern of Polygonatum cyrtonema Hua. and plum trees, The rhizosphere soil microbial community structure of Polygonatum cyrtonema Hua. in the two planting modes were studied by metagenomic sequencing technology. The polysaccharide content, the relative expression of the key enzyme genes involved in polysaccharide synthesis, agronomic traits of Polygonatum cyrtonema Hua. as well as the physicochemical properties of the rhizosphere soil in the two planting modes were determined.Results: Intercropping of plum trees increased the abundance of soil microbial species in rhizosphere soil of Polygonatum cyrtonema Hua., but decreased species diversity and evenness. The species in which intercropping was significantly higher than monocropping was: Burkholderiaceae, Rhodanobacteraceae, Acidobacteriaceae. Intercropping significantly increased the metabolic function of rhizosphere soil, the accumulation of available potassium, and the absorption of total nitrogen and total phosphorus. Leaf polysaccharide content in intercropping was higher than that in monocropping. The relative expression of MPI gene in leaves of intercropping was significantly higher than that in leaves of monocropping. Chlorophyll content and leaf width in intercropping were significantly higher than those in monocropping.Conclusion: Plums/Polygonatum cyrtonema Hua. intercropping increased polysaccharide content in leaves of Polygonatum cyrtonema Hua. and increased the expression of some key enzyme genes for polysaccharide synthesis in leaves of Polygonatum cyrtonema Hua., which might be achieved by regulating the abundance of functional genes of rhizosphere microorganisms related to metabolism in rhizosphere soil, and rhizosphere microorganisms promoting the accumulation of nutrients in rhizosphere soil.Keywords: Metagenomics, Intercropping, Polygonatum cyrtonema Hua., Polysaccharides, Rhizosphere microbial community, Soil physicochemical properties