TITLE:
Auxin Producing Pseudomonas Strains: Biological Candidates to Modulate the Growth of Triticum aestivum Beneficially
AUTHORS:
Atia Iqbal, Shahida Hasnain
KEYWORDS:
Auxin; Pseudomonas; Triticum aestivum; PGPR; Rhizobacteria
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.9,
August
21,
2013
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.