title: [Microbial distribution and 16S rRNA diversity in the rhizosphere soil of Panax notoginseng].
abstract: OBJECTIVE
  We studied the correlation between the microbial diversity in Panax notoginseng root soil and its root rot diseases, to find biological control approaches in Panax notoginseng soil borne diseases.
  
  
  METHODS
  We isolated bacterial strains from the rhizosphere soils of healthy and root rot Panax notoginseng plants that are cultured continuously for 6 years in Wenshan Region. After separation and purification, we obtained DNA. On the basis of 16S rRNA' s general primer we carried out PCR amplification, conducted blast gene similarity and analyzed phylogenetic information.
  
  
  RESULTS
  The isolated bacterial strains distributed to 4 phyla, 40 genera of bacteria, 179 isolates from the samples of healthy Panax notoginseng rhizosphere soil belong to 30 genera and Burkholderia, Arthrobacter, Streptomyces and Bacillus are the dominant microflora. Additionally, 117 isolates from the samples of root rot Panax notoginseng rhizosphere soil belong to 29 genera and Ralstonia, Sphingomonas, Stenotrophomonas as the dominant microflora. Among them, Flavobacterium and Enterobacter were only isolated from the samples of root rot Panax notoginseng rhizosphere soil. At least 5 isolates are novel species; the ions concentration and electrical conductivity value show distinct discrepancy between the two groups (P < 0.05); the microbial amount of dominant species in the healthy soil samples present negative correlation with electrical conductivity value, the concentration of NO3-, SO4(2-), CO3(2-), K+ and total salt (P < 0.01).
  
  
  CONCLUSIONS
  In addition to pathogen infection, the physical and chemical characteristics, microbial community structure and the proportion of dominant species are also closely related to notoginseng continuous cropping soil borne disease. Especially the beneficial microorganisms (Burkholderia, Bacillus, Streptomyces, etc.) abundance is significant to evaluate the soil healthy condition and accurately disease control & forecast for Panax notoginseng cultivation.
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D044822:Biodiversity; D004269:DNA, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D053723:Panax notoginseng / Q000382:microbiology*; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D058441:Rhizosphere; D012988:Soil Microbiology
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S