Abstract
Plant Growth Promoting Rhizobacteria (PGPR) play an important role in agricultural systems, especially as biofertilizer. Previously, we screened one bacterial isolate as indole acetic acid (IAA) producer on the basis of IAA colorimetric assay. Based on morphological, physiological and biochemical characteristics presented in Bergey's Manual of Systematic Bacteriology and on 16SrRNA homology, this isolate identified as Pseudomonas fluorescens (accession # JQ809429). Pseudomonas Fluorescens, like other PGPR isolates, produced IAA in the presence of tryptophan, thus genes for IAA production (iaaM and iaaH) were detected in the present study. Moreover, the overexpression of Synechocystis PCC 6803 glutaredoxin-2 (ssr2061) in Pseudomonas fluorescens cells significantly enhance the growth of the recombinant cells on LB media supplemented with different concentration of NaCl. The recombinant strain was able to produce IAA under 2% of NaCl in the medium. While, the wild type strain failed to produce IAA under same condition. Additionally, effect of the salt on the growth of recombinant and wild type cells was studied by pot culture experiments by using sterilized air dried soil supplemented with 0.5 M or 1 M NaCl. Interestingly, the cell density of the recombinant cells markedly increased even after 6 days from the irrigation with the salt water over the wild type cells. These results suggest that theglutaredoxin-2proteincould play a major role in regulating abiotic tolerance against salt stress in Pseudomonas fluorescens cell.