林下与大田栽培三七根际微生物群落比较分析OA

[Objective]The study aimed to investigate the differences in rhizosphere soil microbial community structure of Panax notoginseng between understory and field cultivation habitats.[Method]Rhizosphere soil samples were collected from understory-cultivated P.notogin-seng(WA,WB)and field-cultivated P.notoginseng(WC,WD).The diversity and composition of bacterial and fungal communities under the two cultivation modes were comparatively analyzed using Illumina NovaSeq 6000 high-throughput sequencing.[Result]The content of notoginsenoside R1 and the total content of five saponins(R1,Rg1,Re,Rb1 and Rd)in understory-cultivated P.notoginseng were signifi-cantly higher than those in field cultivation,with the total saponin content under understory conditions showing a 30.96%increase relative to field cultivation.Total organic carbon(TOC)content and pH in the understory rhizosphere soil were significantly higher than those in the field,whereas available phosphorus and available potassium contents were significantly lower.Bacterial community diversity(Ace,Chao1,Simpson and Shannon indices)in the understory rhizosphere was significantly greater(P<0.05)than that in the field,while no significant difference was observed in fungal community diversity between the two cultivation modes.Redundancy analysis indicated that TOC and pH were the principal environmental factors driving microbial community assembly in the understory rhizosphere,explaining 84.23%and 75.1%of community variation,respectively.The microbial co-occurrence network of the understory rhizosphere exhibited a higher number of nodes(266)and edges(4549)compared with the field network(186 nodes,3407 edges),suggesting greater network complexity.Key hub taxa i-dentified in the understory network included Cylindrocarpon,Paraglomus,Chaetomium,Gemmatimonas and Mortierella,among which Para-glomus,Chaetomium,Gemmatimonas and Mortierella were known biocontrol agents.Correlation analysis revealed that understory microbial community diversity was significantly and positively associated with notoginsenoside R1 content.Specifically,beneficial taxa such as Sphin-gomonas and Mortierella showed positive correlations with R1 content,whereas pathogenic fungi including Sclerotinia were negatively correla-ted with saponin accumulation.[Conclusion]Understory cultivation significantly increases both the saponin content and the rhizosphere bac-terial diversity of P.notoginseng.Organic carbon and pH are the major environmental factors driving microbial community assembly.Understo-ry cultivation establishes a more complex and stable microbial co-occurrence network and enriches beneficial biocontrol fungi such as Para-glomus,Chaetomium and Mortierella,which are positively correlated with saponin content.Collectively,these findings demonstrate that under-story cultivation promotes saponin accumulation in P.notoginseng by optimizing the rhizosphere microecological environment,thereby provi-ding a scientific basis for the efficient and sustainable cultivation of this medicinal plant.