RESUMEN
Plants infection with microorganisms as well as physical factors such as osmotic stresses induced particular secondary metabolite pathways. To investigate the growth promoting effects of two Rhizobacteria strains including Pseudomonas fluoresces [PF] and Putida [PP] in combination with application of water deficit stress on plant biomass of Hyoscyamus niger young roots and variation of tropane alkaloids content and yield in root and shoot parts. Two grams of dried each shoot and root samples was added to appropriate volume of CHCl3: MeOH: NH4OH 25%, [15:5: 1], and sonicated for 20 min. Alkaloids extracted were analyzed by gas chromatographic [GC] method using a Younglin Acme 6000 GC system equipped with a flame ionization detector [FID] and HP-5MS capillary column [30 m x 0.25 mm, film thickness 0.25 micro m]. The identification of alkaloids was based on the comparison of their GC retention time and mass spectra data with their standards substances. Results indicated that the highest alkaloid content values in root [hyoscyamine: 0.26% DW; scopolamine: 0.12% DW] and shoot [hyoscyamine: 0.85% DW; scopolamine: 0.48% DW] were achieved in PF-187 treated plants grown under severe water stress conditions [W3]. By contrast, the maximum alkaloid yield in root [hyoscyamine: 1.92 mg.plant[-1]; scopolamine: 0.83 mg.plant[-1]] and shoot [hyoscyamine: 5.88 mg.plant[-1]; SCO: 3.06 mg.plant[-1]] were obtained in PP-168 treated plants under low water stress conditions [W1]. Rhizobacteria strains can function as environmentally sound tools to increase alkaloids production and counteract growing problems under stress conditions, especially by auxin production