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From 2011.igem.org

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Module 2: Auxin Xpress

Auxin, or Indole 3-acetic acid (IAA), is a plant growth hormone which is produced by several soil bacteria. We have taken the genes encoding the IAA-producing pathway from Pseudomonas savastanoi and expressed them in Escherichia coli. Following chemotaxis towards the roots and uptake by the Phyto Route module, IAA expression will promote root growth with the aim of improving soil stability.

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Overview

Auxin is a well known plant hormone that is responsible for plant growth in response to biotic and abiotic stresses. Usually, synthetic auxins like α-Naphthaleneacetic acid (αNAA) and 2,4-Dichlorophenoxyacetic acid(2,4-D) are used as herbicides. They have been been used effectively for the past fifty years due to their high effectiveness and cheap cost. This high efficiency stems from the interactions that these auxin analogues have with the TIR1 protein. When the analogues bind to the TIR1 protein promoting the formation of the Aux/IAA–SCFTIR1. This leads to the ubiquitylation of of Aux/IAA which usually acts as an inhibitor when bound to ARF transcription factors. Many of the plant's genes are under the control of the ARF transcription factor meaning that any change in the levels of auxin