title: N2-fixation and seedling growth promotion of lodgepole pine by endophytic Paenibacillus polymyxa.
abstract: We inoculated lodgepole pine (Pinus contorta var. latifolia (Dougl.) Engelm.) with Paenibacillus polymyxa P2b-2R, a diazotrophic bacterium previously isolated from internal stem tissue of a naturally regenerating pine seedling to evaluate biological nitrogen fixation and seedling growth promotion by this microorganism. Seedlings generated from pine seed inoculated with strain P2b-2R were grown for up to 13 months in a N-limited soil mix containing 0.7 mM available N labeled as Ca((15)NO3)2 to facilitate detection of N2-fixation. Strain P2b-2R developed a persistent endophytic population comprising 10(2)-10(6) cfu g(-1) plant tissue inside pine roots, stems, and needles during the experiment. At the end of the growth period, P2b-2R had reduced seedling mortality by 14 % and (15)N foliar N abundance 79 % and doubled foliar N concentration and seedling biomass compared to controls. Our results suggest that N2-fixation by P. polymyxa enhanced growth of pine seedlings and support the hypothesis that plant-associated diazotrophs capable of endophytic colonization can satisfy a significant proportion of the N required by tree seedlings growing under N-limited conditions.
authors: IL-7, BC Children's Hospital, 4480 Oak Street, Vancouver, BC, V6H 3V4, Canada. richaaubc@gmail.com
authors: Richa
authors: R
authors: Anand
authors: Susan
authors: S
authors: Grayston
authors: Christopher
authors: C
authors: Chanway
mesh_terms: D060026:Endophytes / Q000302:isolation & purification / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D056507:Paenibacillus / Q000302:isolation & purification / Q000378:metabolism*; D028223:Pinus / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D036226:Seedlings / Q000254:growth & development* / Q000382:microbiology; D014197:Trees / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology
chemical_list: D009584:Nitrogen