الفهرس 
Salt tolerance in relation to BNFOnly 14 pages are availabe for public view
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Abstract
The present study aimed to construct nitrogen fixer and salt tolerant transconjugants via the interspecific conjugation between the effective Rhizobium fredii USDA 205 isolate (which nodulates soybean roots) and the effective Rhizobizrm meliloti ARC 1 isolate (which nodulates alfalfa and has moderated ability to salt tolerance) and the noneffective R.meliloti ARC I04 isolate (which lacks the sym plasmid and has high salinity tolerance). The triparental technique was adapted to transfer the large syrn plasmid from R.fredii USDA 205 to each of R.meliloti ARC 1 and ARC 104 using Tn5- mob and RP4-4 helper plasmid. The obtained results are summarized below: 1- The resistance or sensitivity to specific antibiotics as an additional marker proved that: a- Rhizobizm fiedii USDA 205 exhibited resistance to nalidixic acid pp to 30 pg/ ml. b- Both R. nzeliloti ARC 1 and ARC 104 showed resistance to rifampicin up to 150 pglml. c- E. coli (pSup5011:: Tn5- mob) proved to be resistant to kanamycin up to 10 pg/ ml. d- E. coli (pRP4-4) showed resistance to tetracycline up to 10 pgl ml. Moreover, each specific strain was sensitive to only three of the four tested antibiotics.