Selection of Competitive Strains of Rhizobium Nodulating Phaseolus Vulgaris and Adapted to Environmental Conditions in Egypt,Using the Gus-Reporter Gene Technique |
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Authors: | Shamseldin Abdelaal Werner Dietrich |
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Institution: | 1.Genetic Engineering and Biotechnology Research Instiute, Mubarak City for Scientific Research and Technological Applications, Manchiat El-Olama, Dekheela, P.O. Box 5, Alexandria, Egypt ;2.Fachbereich Biologie, Fachgebiet Zellbiologie und Angewandte Botanik, Phillips-Universit?t Marburg, D-35032, Marburg, Germany ; |
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Abstract: | Two Rhizobium etli strains, EBRI 2 and EBRI 26, isolated from Egypt were tested for nodulation competitiveness on beans using Rhizobium tropici CIAT 899G as the competing strain. The insertion of the gus-reporter transposon mTn5ssgusA30 did not alter the nodulation or nitrogen fixation capacity of mutant strain CIAT 899G compared
to the wild type. At neutral pH, R. etli strains EBRI 2 and EBRI 26 were more competitive than CIAT 899G with the bean cultivar Saxa. These two strains gave nodule
occupancies of 52.1 and 61.1% competing with equal cell numbers of CIAT 899G. Nodule occupancies from these two native strains
increased with the bean cultivar Giza 6 from Egypt to 66 and 67.5%. Based on these results, cultivar Giza 6 was used to select
the most competitive strains under stress of salinity or alkalinity as a major problem for a large part of Egyptian soils.
Under stress of salinity (0.2% NaCl or 34.2 mM NaCl), the salt-sensitive strain EBRI 2 was more competitive than the salt-resistant
strain EBRI 26. Strain EBRI 2 gave 87.4% but strain EBRI 26 gave 63.7% nodule occupancy against CIAT 899G. The same trend
of results was observed under stress of alkalinity (pH 8). Strain EBRI 2 occupied 83% while Strain EBRI 26 occupied 53.2%. |
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Keywords: | Competition Gus fusion R etli R tropici stress of alkalinity stress of salinity |
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