title: Bacteria associated with orchid roots and microbial production of auxin.
abstract: Associative bacteria of terrestrial (Paphiopedilum appletonianum) and epiphytic (Pholidota articulata) tropical orchids were investigated. Microbial community of epiphytic plant differed from that of the terrestrial one. Streptomyces, Bacillus, Pseudomonas, Burkholderia, Erwinia and Nocardia strains populated Paphiopedilum roots, whereas Pseudomonas, Flavobacterium, Stenotrophomonas, Pantoea, Chryseobacterium, Bacillus, Agrobacterium, Erwinia, Burkholderia and Paracoccus strains colonized Pholidota roots. Endophytic bacteria populations were represented with less diversity: Streptomyces, Bacillus, Erwinia and Pseudomonas genera were isolated from P. appletonianum, and Pseudomonas, Bacillus, and Flavobacterium genera were isolated from Ph. articulata. Microorganisms produced indole-3-acetic acid (IAA). Variations in its biosynthesis among the strains of the same genus were also observed. The highest auxin level was detected during the stationary growth phase. Biological activity of microbial IAA was proved by treatment of kidney bean cuttings with bacterial supernatants, revealing considerable stimulation of root formation and growth.
authors.affiliation: Department of Microbiology, Biological Faculty, Moscow State University, Vorob'evy gory, 119992 Moscow, Russia. tsavkelova@mail.ru
authors.forename: Elena A
authors.initials: EA
authors.lastname: Tsavkelova
authors.forename: Tatiana A
authors.initials: TA
authors.lastname: Cherdyntseva
authors.forename: Svetlana G
authors.initials: SG
authors.lastname: Botina
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Netrusov
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044822:Biodiversity; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000382:microbiology*; D027805:Phaseolus / Q000187:drug effects / Q000254:growth & development; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000382:microbiology*; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; C030737:indoleacetic acid