Development of Tn5 Mutants of Cicer-Rhizobium Strains Tolerant to Nitrate under Symbiotic Condition*

Transposon Tn5 mutants of two Cicer-Rhizobium strains, G36–84 and F-75 tolerant to nitrate under symbiotic condition, have been developed. Suicide vector pGS9 was used as a source of Tn5 for insertion mutagenesis of Rhlzoblum. The mutants so developed were screened in the presence of nitrate under symbiotic condition for nodule formation (Nod) and N₂-fixatlon (Fix) ability. We could get some mutants, which were Nod⁺ Fix⁺ at 1mM and 2 mM nitrate, from the parental strains which were Nod⁻ at 1rriM nitrate.