Auxin Producing Pseudomonas Strains: Biological Candidates to Modulate the Growth of Triticum aestivum Beneficially

Atia Iqbal, Shahida Hasnain

Department of Microbiology and Molecular Genetics, University of Punjab, Lahore, Pakistan;.

DOI: 10.4236/ajps.2013.49206                

Abstract

The screening of plant growth promoting rhizobacteria is a crucial step for their utilization as beneficial input in improving the crop productivity. This study was carried out to screen and evaluate the auxin producing rhizospheric isolated Pseudomonas strains for their potential to improve growth of Triticum aestivum (wheat) plant under laboratory and natural conditions. Three strains PNS-4, PNS-6 and PNS-15 were evaluated for auxin production by Salkowski’s method and further confirmed by high performance liquid chromatography (HPLC). The PNS-4, PNS-6 and PNS-15 strains were identified by I6S rRNA gene sequencing that showed maximum resemblance with Pseudomonas mendocina (99%), Pseudomonas alcaliphila (99%) and Pseudomonas sp. (99%) respectively. Selected strains were found to produce auxin with and without the amendment of exogenously applied L-tryptophan, a major precursor for auxin biosynthesis and an important constituent of plant root exudates. Efficacy of these strains on wheat plant growth was checked under laboratory and field conditions. All Pseudomonas species were found to improve the % seed germination and growth parameters (shoot length, root length, fresh weight and dry weight) of the wheat seedlings significantly (P = 0.05) as compared to the un-inoculated seedlings under laboratory condition. The biochemical parameters (total soluble protein content and endogenous auxin content) of the bacterial inoculated wheat seedling were also increased significantly than that of uninoculated ones. Under natural condition, seed bacterization also showed the significant effect (P = 0.05) on yield parameters (shoot length, number of tillers, spike length and weight of seeds in grams) of the wheat plants when compared with non-inoculated plants. Our results reported the three most promising Pseudomonas candidates and revealed the fact that experiments under laboratory and natural conditions may be helpful in selecting the best candidates as bio fertilizers for future agricultural practices.

Keywords

Auxin; Pseudomonas; Triticum aestivum; PGPR; Rhizobacteria

Conflicts of Interest

The authors declare no conflicts of interest.

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