地黄中主要次生代谢产物在根际土壤中分布及其对细菌群落特征的影响

目的 分析地黄Rehmannia glutinosa中的次生代谢产物在地黄根际土壤中的分布特征及其对根际土壤细菌群落特征的影响，为揭示地黄连作土壤形成过程中根系分泌物与根际微生物之间互作机制的研究提供理论参考。方法 以7、8、10月金九地黄根际土壤为研究对象，采用HPLC分析3个时期地黄根际土壤中苯乙醇苷类、环烯醚萜苷类及酚酸类次生代谢产物的分布；通过llumina MiSeq高通量测序法分析根际土壤中细菌群落的结构特征；利用SIMCA 14.1、SPSS 27等软件分析3个生长时期根际土壤中次生代谢产物及细菌群落结构的差异性，筛选出引起两者差异性的主要次生代谢产物和标志性菌群，并结合Canoco 5.0软件分析两者之间的相关性。结果 地黄3个生长时期根际土壤中均检测到6种苯乙醇苷类成分、3种环烯醚萜苷类成分及5种酚酸类成分，各单体成分的含量变化差异较大，其中香豆酸、异类叶升麻苷、红景天苷、香草酸为主要差异物质；地黄根际土壤中优势细菌的相对丰度随生育进程而发生变化，门水平及属水平上的放线菌门、厚壁菌门、绿弯菌门、不明蓝藻菌属、Gaiella的相对丰度逐渐降低，酸杆菌门、拟杆菌门、浮霉菌门、疣微菌门、热酸菌属、不明酸杆菌属的相对丰度则逐渐增加；相关性分析及冗余分析表明根际土壤中次生代谢产物与细菌群落结构之间存在着一定相关性，其中香豆酸、对羟基苯甲酸对根际细菌群落结构的影响较大。结论 地黄中的主要次生代谢产物在地黄根际土壤中均可以检测到，而且对根际土壤细菌群落的结构特征产生了一定影响。

Distribution of major secondary metabolites from Rehmanniae Radix in rhizosphere soil and their effects on bacterial community characteristics

Objective To investigate the distribution characteristics of secondary metabolites in rhizosphere soil of Dihuang (Rehmanniae Radix) and their effects on bacterial community characteristics in rhizosphere soil, and to provide theoretical reference for the study of the interaction mechanism between root exudates and rhizosphere microorganisms during the formation of Rehmanniae Radix continuous cropping soil. Methods The rhizosphere soil of Jinjiu Rehmanniae Radix in July, August, and October was selected as the research object. First, the distribution of secondary metabolites of phenylethanosides, iridoid glycosides, and phenolic acids in the rhizosphere soil of three periods was analyzed by high performance liquid chromatography (HPLC). Secondly, the structural characteristics of bacterial community in rhizosphere soil were analyzed by llumina MiSeq high-throughput sequencing. Finally, SIMCA 14.1 and SPSS 27 software were used to analyze the differences of secondary metabolites and bacterial community structure in rhizosphere soil among the three growth stages, and the main secondary metabolites and marker bacteria that caused the differences were screened out. Canoco 5.0 software was used to analyze the correlation between them. Results A total of six phenylethanosides, three iridoid glycosides and five phenolic acids were detected in the rhizosphere soil of Rehmanniae Radix during the three growth stages. The content of each monomer varied greatly, with coumaric acid, heterologous cimicifuga glycoside, salidroside and vanillic acid being the main difference substances. The relative abundance of dominant bacteria in the rhizosphere soil changed with the growth process. At the phylum and genus levels, the relative abundance of Actinobacteria, Firmicutes, Chloroflexi, Unidentified Cyanobacteria and Gaiella gradually decreased, while that of Acidobacteria, Bacteroidetes, Planctomycetes, Verrucomicrobia, Acidothermus and Unidentified Acidobacteria gradually increased. Results of correlation analysis and redundancy analysis showed that there was a certain correlation between secondary metabolites and bacterial community structure in rhizosphere soil, with coumaric acid and p-hydroxybenzoic acid having greater effects on rhizosphere bacterial community structure. Conclusion The main secondary metabolites of Rehmanniae Radix can be detected in the rhizosphere soil of Rehmanniae Radix, and have certain effects on the structural characteristics of bacterial community in rhizosphere soil.