PRODUCTION OF INDOLE ACETIC ACID BY 5-FLURO-TRYPTOPHAN RESISTANT MUTANT OF RHIZOBIUM SP. ISOLATED FROM ROOT NODULE OF PULSE LEGUME PHASEOLUS MUNGO L.

Abstract

A symbiotic strain was isolated from the root nodules of the legume pulse Phaseolus mungo L and designated as PM 25. The strain was identified as Rhizobium sp. on the basis of the physiobiochemical characteristics and 16S rDNA sequence based homology. The Minimum Inhibitory Concentration of the analogue 5-fluro-tryptophan was 3.0 mM. The analogue (5FT) resistant mutants were   screened from wild PM 25 strain after mutagenesis with N-methyl-N´-nitro-N-nitrosoguanidine (NTG) as a mutagenic agent. The analogue resistant mutants were isolated from 5.0 mM and 10.0 mM 5-fluro-tryptophan supplemented Bergersen’s medium. These mutants produced tryptophan and IAA in Bergersen’s medium without supplemented with tryptophan. The wild type PM 25 was unable to produce tryptophan and IAA in tryptophan nonsupplemented medium but capable of producing IAA in tryptophan supplemented media. So, this Rhizobium sp. is able to follow tryptophan dependent pathway and able to convert tryptophan to IAA.