Community Analysis of Endophytic Bacteria from the Seeds of the Medicinal Plant Panax notoginseng

Panax notoginseng is a traditional Chinese medicine. The roots of P. notoginseng can be used for treatment of diseases and raw materials in Chinese medicinal products. High yield and quality roots require cultivation in shade and humid conditions for 3 years. The long period cultivation makes P. notoginseng vulnerable to infect by pathogens. So control diseases are vital for the high yield and quality of P. notoginseng. The seed is the carrier systems of many probiotics and pathogens. To explore the indigenous bacterial community diversity, the endophytic bacteria from the seeds of the medicinal plant P. notoginseng were isolated and identified using traditional cultivation methods in combination with molecular technique. A total of 137 endophytic bacteria strains were isolated. The 16S rDNA of these strains was amplified and subjected to amplified ribosomal DNA restriction analysis (ARDRA) with restriction enzyme HaeIII. All the isolated strains were grouped into 9 OTUs (Operational Taxonomic Units) on the basis of the similarity of the ARDRA band profiles. Each representative strain of 9 OTUs was selected for sequencing. r-proteobacteria was the most dominant group among the isolates (98.5%), containing eight genera. Pseudomonas was the most dominant genus (58 of 135 isolates), whose isolates occurred in the seeds collected from all three places. The second dominant genus was Enterobacter (20.7%), followed by uncultured bacterium (14.8%) and Stenotrophomonas (10.4%). Among the six areas sampled, endophytic bacteria in the seeds collected from Panlong of Yanshan exhibited species diversity and contained the most isolates. These results suggest an abundant diversity of bacterial community within the seeds of P. notoginseng. These data provide insights into monitoring the seed health and disease outbreak during seeding.