title: Phylogenetic diversity of bacterial endophytes of Panax notoginseng with antagonistic characteristics towards pathogens of root-rot disease complex.
abstract: Endophytes play an important role in protection of host plants from infection by phytopathogens. Endophytic bacteria were isolated from five different parts (root, stem, petiole, leaf and seed) of Panax notoginseng and evaluated for antagonistic activity against Fusarium oxysporum, Ralstonia sp. and Meloidogyne hapla, three major pathogens associated with root-rot disease complex of P. notoginseng. From 1000 endophytic bacterial strains evaluated in vitro, 104 strains exhibited antagonistic properties against at least one of these three pathogens. Phylogenetic analyses of their 16S rRNA gene sequences showed that these 104 antagonistic bacteria belong to four clusters: Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes/Chlorobi. Members of the Firmicutes, in particular the Bacillus spp., were predominant in all analyzed tissues. The root was the main reservoir for antagonistic bacteria. Of the 104 antagonists, 51 strains showed antagonistic activities to one pathogen only, while 43 and 10 displayed the activities towards two and all three pathogens, respectively. The most dominant species in all tissues were Bacillus amyloliquefaciens subsp. plantarum and Bacillus methylotrophicus, which were represented by eight strains with broad antagonistic spectrum to the all three test pathogens of root-rot disease complex of P. notoginseng.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources & Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Yong Hong
authors.initials: YH
authors.lastname: Cao
authors.forename: Ming Hui
authors.initials: MH
authors.lastname: Cheng
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Ming He
authors.initials: MH
authors.lastname: Mo
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Jian Zhong
authors.initials: JZ
authors.lastname: Yang
authors.forename: Fa Xiang
authors.initials: FX
authors.lastname: Yang
mesh_terms: D000818:Animals; D000898:Antibiosis; D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D060026:Endophytes / Q000145:classification / Q000302:isolation & purification / Q000502:physiology; D005670:Fusarium / Q000254:growth & development*; D008969:Molecular Sequence Data; D053723:Panax notoginseng / Q000382:microbiology*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D043367:Ralstonia / Q000254:growth & development*; D017422:Sequence Analysis, DNA; D014431:Tylenchoidea / Q000254:growth & development*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S