Indole-3-acetic acid synthesis by plant growth promoting Klebsiella sp. (PGPB1) via indole 3-pyruvic acid pathway and its uptake in plants
2019
Alvarez, P.L.J. | Marca, F.E. | Fernando, L.M. | Rallos, R.V. | Mendoza, C.O.
15N-labeled tryptophan was used to trace the synthesis of indole-3-acetic acid (IAA) by plant growth promoting Klebsiella sp. (PGPB1). Preliminary thin layer chromatography analysis of crude extracts showed that IAA was produced from labeled tryptophan. This is further supported by high pressure liquid chromatography wherein the components of the crude extracts separated to two major peaks corresponding to indole-3-acetic acid (IAA) and indole-3-pyruvic acid (IPyA). Using Salkowski colorimetric assay, the extract was found to contain 11.81±5.98×103 ppm of IAA and 56.91±0.35 ppm of IPyA. The crude extract, IAA and IPyA fractions were found to be enriched with 15N. Likewise, the presence of higher concentration of IPyA in the extract indicates that PGPB1 is probably using the IPyA pathway in synthesizing IAA Rice seedlings germinated and grown in the 15N-labeled IAA produced by PGPB1 showed significant differences from the control treatment in terms of higher fresh weight, root length, and shoot length. Rice seedlings were also found to be enriched in 15N, confirming that they were able to take up the applied 15N-labeled IAA.
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