Cytokinin production by Paenibacillus polymyxa

The production of hormones has been suggested to be one of the mechanisms by which plant growth-promoting rhizobacteria (PGPR) stimulate plant growth. To evaluate whether the free-living soil bacterium, Paenibacillus polymyxa, releases the hormone group cytokinins and, if so, their identity, the content of cytokinins in the growth media, before and after cultivation of this bacterium, was determined by immunoanity chromatography (IAC). This method allows the isolation of almost all known cytokinins and their metabolites. Separation and characterization were done by high performance liquid chromatography (HPLC) with on-line ultraviolet (UV) detection, and ®nal identi®cation was by gas chromatography-mass spectrometry. Isopentenyladenine (iP) was identi®ed in the two de®ned media used for the cultivation of P. polymyxa, but not earlier than at its late stationary growth. A third medium, supplemented with yeast extract, contained iso-pentenyladenine riboside (iPR) and some additional cytokinin-like substances before inoculation. When the same medium was sampled after the cultivation of P. polymyxa up to its logarithmic growth phase, the cytokinin concentration had decreased. After prolonged cultivation of P. polymyxa, small amounts of iP appeared in all three media, and iPR had disappeared from the yeast-containing medium, which indicates that the bacterium can metabolize cytokinins. # 1999 Elsevier Science Ltd. All rights reserved.

[1]  J. Sørensen,et al.  Multi-target and medium-independent fungal antagonism by hydrolytic enzymes in Paenibacillus polymyxa and Bacillus pumilus strains from barley rhizosphere , 1997 .

[2]  C. Chanway,et al.  Response of crested wheatgrass (Agropyron cristatum L.) perennial ryegrass (Lolium perenne and white clover (Trifolium repens L.) to inoculation with Bacillus polymyxa , 1988 .

[3]  R. Bieleski.  THE PROBLEM OF HALTING ENZYME ACTION WHEN EXTRACTING PLANT TISSUES. , 1964, Analytical biochemistry.

[4]  M. H. Gaskins,et al.  Plant Growth Substances Produced by Azospirillum brasilense and Their Effect on the Growth of Pearl Millet (Pennisetum americanum L.) , 1979, Applied and environmental microbiology.

[5]  U. Granhall,et al.  Isolation and Characterization of Dinitrogen-Fixing Bacteria from the Rhizosphere of Temperate Cereals and Forage Grasses , 1984, Applied and environmental microbiology.

[6]  R. O. Scott,et al.  SOLUBILIZATION OF MINERALS AND RELATED MATERIALS BY 2‐KETOGLUCONIC ACID‐PRODUCING BACTERIA , 1963 .

[7]  L. Seldin,et al.  Production of a potentially novel anti-microbial substance by Bacillus polymyxa , 1993, World journal of microbiology & biotechnology.

[8]  T. Heulin,et al.  Effect of inoculation with Bacillus polymyxa on soil aggregation in the wheat rhizosphere: preliminary examination , 1993 .

[9]  G. Björk,et al.  Synthesis and function of isopentenyl adenosine derivatives in tRNA. , 1994, Biochimie.

[10]  Rex L. Smith,et al.  Responses of Sorghum and Pennisetum Species to the N2-Fixing Bacterium Azospirillum brasilense , 1984, Applied and environmental microbiology.

[11]  T. Heulin,et al.  In vitro chitinase and antifungal activity of a soil, rhizosphere and rhizoplane population of Bacillus polymyxa , 1994 .

[12]  W. Frankenberger,et al.  Biosynthesis of cytokinins by Azotobacter chroococcum , 1989 .

[13]  T. Heulin,et al.  Bacillus polymyxa and Rahnella aquatilis, the dominant N2-fixing bacteria associated with wheat rhizosphere in french soils , 1994 .

[14]  G. Stenlid.  Cytokinins as inhibitors of root growth , 1982 .

[15]  S. Albrecht,et al.  Methods for Growing Spirillum lipoferum and for Counting It in Pure Culture and in Association with Plants , 1977, Applied and environmental microbiology.

[16]  Y. Okon,et al.  Effect of Azospirillum inoculation on yield of field-grown wheat , 1983 .

[17]  R. Hardy,et al.  Enhanced Mineral Uptake by Zea mays and Sorghum bicolor Roots Inoculated with Azospirillum brasilense , 1983, Applied and environmental microbiology.

[18]  R. Amasino,et al.  Inhibition of Leaf Senescence by Autoregulated Production of Cytokinin , 1995, Science.

[19]  R. O. Morris,et al.  Zeatin-Like Cytokinins in Yeast: Detection by Immunological Methods , 1989 .

[20]  R. O. Morris,et al.  Secretion of Zeatin, Ribosylzeatin, and Ribosyl-1'' -Methylzeatin by Pseudomonas savastanoi: Plasmid-Coded Cytokinin Biosynthesis. , 1986, Plant physiology.