THE EFFECTS OF LEAD-RESISTANT PSEUDOMONADS ON THE GROWTH OF TRITICUM-AESTIVUM SEEDLINGS UNDER LEAD STRESS

Five Pseudomonad strains, SPb-1, SPb-2, SPb-3 (from a water sample), SPb-4, and SPb-5 (from rhizosphere), which could tolerate lead acetate up to 1000 mug ml-1, were isolated from an industrially polluted area around Kasoor, Pakistan. Only SPb-5 harbours a lead-resistant plasmid. Triticum aestivum seeds inoculated with strains SPb-4 and SPb-5 were germinated and grown under different concentrations (0, 1, 5, 10, 15, and 20 mM) of lead acetate for ten days. Germination and seedling growth were adversely affected Poor growth was associated with increased lead content of seedlings. With bacterial inoculation, germination and seedling growth were improved, as compared with non-inoculated treatments. Stimulation in the growth of seedlings was accompanied by a decrease in lead content, as compared with non-inoculated treatments.