An ipdC gene knock-out of Azospirillum brasilense strain SM and its implications on indole-3-acetic acid biosynthesis and plant growth promotion

Phytohormone-like acting compounds previously have been suggested to be involved in the phytostimulatory action exerted by the plant-beneficial rhizobacterium Bacillus amyloliquefaciens FZB42. Analyses by high-performance liquid chromatography and gas chromatography-mass spectrometry performed with culture filtrates of FZB42 demonstrated the presence of indole-3-acetic acid (IAA), corroborating it as one of the pivotal plant-growth-promoting substances produced by this bacterium. In the presence of 5 mM tryptophan, a fivefold increase in IAA secretion was registered. In addition, in the trp auxotrophic strains E101 (ΔtrpBA) and E102 (ΔtrpED), and in two other strains bearing knockout mutations in genes probably involved in IAA metabolism, E103 (ΔysnE, putative IAA transacetylase) and E105 (ΔyhcX, putative nitrilase), the concentration of IAA in the culture filtrates was diminished. Three of these mutant strains were less efficient in promoting plant growth, indicating that the Trp-dependent synthesis of auxins and plant growth promotion are functionally related in B. amyloliquefaciens.

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Plant Growth Promotion Efficacy of Indole Acetic Acid (IAA) Produced by a Mangrove Associated Fungi-Trichoderma viride VKF3

International Journal of Current Microbiology and Applied Sciences ◽

10.20546/ijcmas.2017.611.317 ◽

2017 ◽

Vol 6 (11) ◽

pp. 2692-2701 ◽

Cited By ~ 5

Author(s):

Nathan Vinod Kumar ◽

K. Subha Rajam ◽

Mary Esther Rani

Keyword(s):

Acetic Acid ◽

Plant Growth ◽

Plant Growth Promotion ◽

Indole Acetic Acid ◽

Growth Promotion ◽

Trichoderma Viride

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Phenotypic variation in Azospirillum brasilense Sp7 does not influence plant growth promotion effects

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2013.09.008 ◽

2013 ◽

Vol 67 ◽

pp. 255-262 ◽

Cited By ~ 6

Author(s):

Victoria Volfson ◽

Sharon Fibach-Paldi ◽

Natalia Soledad Paulucci ◽

Marta Susana Dardanelli ◽

Ofra Matan ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Phenotypic Variation ◽

Azospirillum Brasilense ◽

Growth Promotion ◽

Azospirillum Brasilense Sp7

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Rhizobium leguminosarum as a plant growth-promoting rhizobacterium: direct growth promotion of canola and lettuce

Canadian Journal of Microbiology ◽

10.1139/m96-040 ◽

1996 ◽

Vol 42 (3) ◽

pp. 279-283 ◽

Cited By ~ 129

Author(s):

T. C. Noel ◽

C. Sheng ◽

C. K. Yost ◽

R. P. Pharis ◽

M. F. Hynes

Keyword(s):

Acetic Acid ◽

Plant Growth ◽

Rhizobium Leguminosarum ◽

Growth Promotion ◽

Plant Growth Promoting Rhizobacteria ◽

Plant Growth Promoting ◽

Direct Growth ◽

Early Seedling ◽

Growth Promoting ◽

Indole 3 Acetic Acid

Early seedling root growth of the nonlegumes canola (Brassica campestris cv. Tobin, Brassica napus cv. Westar) and lettuce (Lactuca saliva cv. Grand Rapids) was significantly promoted by inoculation of seeds with certain strains of Rhizobium leguminosarum, including nitrogen- and nonnitrogen-fixing derivatives under gnotobiotic conditions. The growfh-promotive effect appears to be direct, with possible involvement of the plant growth regulators indole-3-acetic acid and cytokinin. Auxotrophic Rhizobium mutants requiring tryptophan or adenosine (precursors for indole-3-acetic acid and cytokinin synthesis, respectively) did not promote growth to the extent of the parent strain. The findings of this study demonstrate a new facet of the Rhizobium–plant relationship and that Rhizobium leguminosarum can be considered a plant growth-promoting rhizobacterium (PGPR).Key words: Rhizobium, plant growth-promoting rhizobacteria, PGPR, indole-3-acetic acid, cytokinin, roots, auxotrophic mutants.

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