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| Characterization of Two Drought-Tolerant PGPB: Azospirillum brasilense NO40 and Stenotrophomonas maltophilia / | |||||
| تخصص البحث : Basic Sciences | |||||
| Mansoura Journal of Environmental Sciences - Egypt JOESE / Vol.46 No. 2 - June2017 | |||||
| Samar Salama - مؤلف رئيسي | |||||
| Mohammed N. Omar | |||||
| Mohammed E. Osman | |||||
| Wedad A. Kasim | |||||
| Keywords: Azospirillum brasilense Drought PGPB Spermosphere Stenotrophomonas maltophilia |
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| Development of plant growth-promoting bacteria (PGPB) to enhance the growth and productivity of agronomic crops under normal and drought-stressed conditions can offer a rapid, low-cost and eco-friendly solution to meet the ever-increasing worldwide food demand. However, the selection of such PGPB is not necessarily straightforward. In this work, two PGPB, Azospirillum brasilense NO40 and an isolate identified (using 16S rDNA sequence analysis) as Stenotrophomonas maltophilia were tested as potential candidates for enhancing wheat tolerance to drought stress. Both were previously screened for the ability to fix atmospheric nitrogen and for tolerating concentrations of polyethylene glycol 6000 (PEG6000) up to 30%. The survival of the selected strains was tested under higher concentrations of PEG (up to 50%). Additionally, the effect of 25% PEG on the bacterial growth rate, culture pH and the bacterial plant growth promoting traits was studied. Finally, the capacity of the selected bacteria to enhance the tolerance of wheat seedlings to drought stress was studied in a sterilized spermosphere model. The two selected strains could survive concentrations of PEG up to 50%. The cultures’ pH was slightly alkaline over time and the cell densities were lower in the PEG-containing cultures. However, the selected strains were able to maintain their plant growth-promoting abilities under stress and consequently enhanced the lengths, fresh and dry weights and the relative water contents of wheat seedlings. Therefore, screening bacteria for tolerance to high PEG concentrations and desirable plant growth promotion traits can provide PGPB that should facilitate agricultural productivity under limited water supply. |
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