Pigment diverse mutants of Pseudomonas sp.: inhibition of fungal growth and stimulation of growth of Cicer arietinum

A Pseudomonas strain MRS16 inhibited growth of different pathogenic fungi ( Aspergillus sp., Fusarium oxysporum, Pythium aphanidermatum and Rhizoctonia solani) in vitro. Larger inhibition zones were obtained on nutrient agar a nd King's B media compared to potato dextrose agar and pigment production m edia. Mutants altered in production of fluorescent pigment were derived by nitrosoguanidine mutagenesis. The pigment overproducer mutant MRS16M-1 was more inhibitory whereas nonproducer mutant MRS16M-5 was less inhibitory tha n parent strain on nutrient agar medium. Addition of iron (100 muM FeCl3) i n the medium decreased inhibition of fungal growth, suggesting the involvem ent of siderophores and other antifungal secondary metabolites. Seed bacter ization of two cultivars of chickpea (Cicer arietinum cvs. H8618 and C235) differing in susceptibility to wilt caused initial root and shoot stunting at 5 d of growth followed by proliferation of secondary root growth at 10 d . Coinoculation of chickpea with Pseudomonas strain MRS16 or mutants and Rh izobium sp. Cicer strain Ca181 enhanced nodulation, nitrogen fixation and p lant dry mass as compared to single inoculation with Rhizobium strain under sterile conditions.