Record ID No. |
1593 |
Author(s) |
Marulanda A., Barea J M, Azcon R. , 2009 |
Affiliation |
Consejo Superior de Investigaciones CientÃficas (CSIC), Dept Microbiol Suelo & Sistemas Simbiot, Estac Expt Zaidin, Prof Albareda 1, E-18008 Granada, SPAIN |
Title |
Stimulation of Plant Growth and Drought Tolerance by Native Microorganisms (AM Fungi and Bacteria) from Dry Environments: Mechanisms Related to Bacterial Effectiveness |
Source. Vol.(no):Page |
Journal of Plant Growth Regulation. 28(2):115-124p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Miscellaneous |
Country |
Spain, Europe |
Abstracts |
In this study we tested whether rhizosphere microorganisms can increase drought tolerance to
plants growing under water-limitation conditions. Three indigenous bacterial strains isolated from droughted
soil and identified as Pseudomonas putida, Pseudomonas sp., and Bacillus megaterium were able to stimulate
plant growth under dry conditions. When the bacteria were grown in axenic culture at increasing osmotic stress
caused by polyethylene glycol (PEG) levels (from 0 to 60%) they showed osmotic tolerance and only Pseudomonas
sp. Decreased indol acetic acid (IAA) production concomitantly with an increase of osmotic stress (PEG) in the
medium. P. Putida and B. Megaterium exhibited the highest osmotic tolerance and both strains also showed
increased proline content, involved in osmotic cellular adaptation, as much as increased osmotic stress caused
by NaCl supply. These bacteria seem to have developed mechanisms to cope with drought stress. The increase in
IAA production by P. Putida and B. Megaterium at a PEG concentration of 60% is an indication of bacterial
resistance to drought. Their inoculation increased shoot and root biomass and water content under drought
conditions. Bacterial IAA production under stressed conditions may explain their effectiveness in promoting
plant growth and shoot water content increasing plant drought tolerance. B. Megaterium was the most efficient
bacteria under drought (in successive harvests) either applied alone or associated with the autochthonous
arbuscular mycorrhizal fungi Glomus coronatum, Glomus constrictum or Glomus claroideum. B. Megaterium colonized
the rhizosphere and endorhizosphere zone. We can say, therefore, that microbial activities of adapted strains
represent a positive effect on plant development under drought conditions. |