title: Plant growth-promoting nitrogen-fixing enterobacteria are in association with sugarcane plants growing in Guangxi, China.
abstract: The current nitrogen fertilization for sugarcane production in Guangxi, the major sugarcane-producing area in China, is very high. We aim to reduce nitrogen fertilization and improve sugarcane production in Guangxi with the help of indigenous sugarcane-associated nitrogen-fixing bacteria. We initially obtained 196 fast-growing bacterial isolates associated with the main sugarcane cultivar ROC22 plants in fields using a nitrogen-deficient minimal medium and screened out 43 nitrogen-fixing isolates. Analysis of 16S rRNA gene sequences revealed that 42 of the 43 nitrogen-fixing isolates were affiliated with the genera Enterobacter and Klebsiella. Most of the nitrogen-fixing enterobacteria possessed two other plant growth-promoting activities of IAA production, siderophore production and phosphate solubilization. Two Enterobacter spp. strains of NN145S and NN143E isolated from rhizosphere soil and surface-sterilized roots, respectively, of the same ROC22 plant were used to inoculate micropropagated sugarcane plantlets. Both strains increased the biomass and nitrogen content of the sugarcane seedlings grown with nitrogen fertilization equivalent to 180 kg urea ha(-1), the recommended nitrogen fertilization for ROC22 cane crops at the seedling stage. (15)N isotope dilution assays demonstrated that biological nitrogen fixation contributed to plant growth promotion. These results suggested that indigenous nitrogen-fixing enterobacteria have the potential to fix N(2) associated with sugarcane plants grown in fields in Guangxi and to improve sugarcane production.
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.forename: Zhengyi
authors.initials: Z
authors.lastname: Li
authors.forename: Chunjin
authors.initials: C
authors.lastname: Hu
authors.forename: Xincheng
authors.initials: X
authors.lastname: Zhang
authors.forename: Siping
authors.initials: S
authors.lastname: Chang
authors.forename: Litao
authors.initials: L
authors.lastname: Yang
authors.forename: Yangrui
authors.initials: Y
authors.lastname: Li
authors.forename: Qianli
authors.initials: Q
authors.lastname: An
mesh_terms: D001483:Base Sequence; D002681:China; D018556:Crops, Agricultural / Q000254:growth & development / Q000382:microbiology; D004754:Enterobacter / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D005308:Fertilizers / Q000706:statistics & numerical data; D007210:Indoleacetic Acids / Q000378:metabolism; D007709:Klebsiella / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000235:genetics; D010710:Phosphates / Q000378:metabolism; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D031786:Saccharum / Q000254:growth & development / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D017262:Siderophores / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D005308:Fertilizers; D007210:Indoleacetic Acids; D010710:Phosphates; D012336:RNA, Ribosomal, 16S; D017262:Siderophores; C030737:indoleacetic acid; D010088:Oxidoreductases; C029130:nitrogenase reductase; D009584:Nitrogen