An <Emphasis Type="Italic">ipdC</Emphasis> gene knock-out of <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> strain SM and its implications on indole-3-acetic acid biosynthesis and plant growth promotion |
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Authors: | Mandira Malhotra Sheela Srivastava |
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Institution: | (1) Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India |
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Abstract: | The indole-3-pyruvate decarboxylase gene (ipdC), coding for a key enzyme of the indole-3-pyruvic acid pathway of IAA biosynthesis in Azospirillum brasilense SM was functionally disrupted in a site-specific manner. This disruption was brought about by group II intron-based Targetron
gene knock-out system as other conventional methods were unsuccessful in generating an IAA-attenuated mutant. Intron insertion
was targeted to position 568 on the sense strand of ipdC, resulting in the knock-out strain, SMIT568s10 which showed a significant (∼50%) decrease in the levels of indole-3-acetic
acid, indole-3-acetaldehyde and tryptophol compared to the wild type strain SM. In addition, a significant decrease in indole-3-pyruvate
decarboxylase enzyme activity by ∼50% was identified confirming a functional knock-out. Consequently, a reduction in the plant
growth promoting response of strain SMIT568s10 was observed in terms of root length and lateral root proliferation as well
as the total dry weight of the treated plants. Residual indole-3-pyruvate decarboxylase enzyme activity, and indole-3-acetic
acid, tryptophol and indole-3-acetaldehyde formed along with the plant growth promoting response by strain SMIT568s10 in comparison
with an untreated set suggest the presence of more than one copy of ipdC in the A. brasilense SM genome. |
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Keywords: | Gene knock-out Indole-3-acetic acid Indole-3-pyruvate decarboxylase Targetron Plant growth promoting ability |
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