Physiological, Biochemical and Molecular Characterization of Azospirillum Spp. Isolated from Maize under Water Stress

This study was designed to isolate and characterize Azospirillum strains from maize (Zea mays L.) grown under wellwatered and water stressed conditions and to evaluate the ability of bacteria to produce plant growth promoting hormones like Indole Acetic Acid (IAA), Gibberellic Acid (GA), trans-Zeatin riboside (tzr) and abscisic acid (ABA). A total of eight strains of Azospirillum were isolated from rhizosphere and roots of maize plants grown in pots and it was observed that survival efficiency of Azospirillum from well watered plants was higher as compared to that of Azospirillum strains isolated from roots and rhizosphere samples of water stressed plants (having 8-12% soil moisture). Preliminary identification of isolates was made on the basis of morphological characteristics and carbon/nitrogen source utilization patterns using QTS24 kits. The genetic diversity among the isolates was evaluated by Randomly Amplified Polymorphic DNA finger printing and similarity matrix. Inoculation of wheat with isolates from water-stressed plants induced tolerance to water stress in inoculated plants. Isolates from water-stressed conditions produced low concentration of indole acetic acid, gibberellic acid, and trans zeatin riboside but higher concentration of abscisic acid. The isolated bacterial strains have technological implications for inoculants formulation and improved growth of cereal crops.