Selection of competitive strains of Rhizobium nodulating Phaseolus vulgaris and adapted to environmental conditions in Egypt, using the gus-reporter gene technique

Abdelaal A Shamseldin, Dietrich Werner

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

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%.

Original languageEnglish (US)
Pages (from-to)377-382
Number of pages6
JournalWorld Journal of Microbiology and Biotechnology
Volume20
Issue number4
DOIs
StatePublished - Jun 1 2004

Keywords

  • Competition
  • Gus fusion
  • R. etli
  • R. tropici
  • Stress of alkalinity
  • Stress of salinity

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