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Biosafety of Genetically Modified Organisms 2

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Front. Plant Sci. | doi: 10.3389/fpls.2018.00233

Overexpressing exogenous 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) genes increases fecundity and auxin content of transgenic Arabidopsis plants

Jia Fang1,  Peng Nan1, Zongying Gu1,  Xiaochun Ge1,  Yu-Qi Feng2 and  Baorong Lu1*
  • 1Fudan University, China
  • 2Wuhan University, China

Transgenic glyphosate-tolerant plants overproducing EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) may exhibit enhanced fitness in glyphosate-free environments. If so, introgression of transgenes overexpressing EPSPS into wild relative species may lead to increased competitiveness of crop-wild hybrids, resulting in unpredicted environmental impact. Assessing fitness effects of transgenes overexpressing EPSPS in a model plant species can help address this question, while elucidating how overproducing EPSPS affects the fitness-related traits of plants. We produced segregating T2 and T3 Arabidopsis thaliana lineages with or without a transgene overexpressing EPSPS isolated from rice or Agrobacterium (CP4). For each of the three transgenes, we compared glyphosate tolerance, some fitness-related traits, and auxin (indole-3-acetic acid) content in transgene-present, transgene-absent, empty vector (EV), and parental lineages in a common-garden experiment. We detected substantially increased glyphosate tolerance in T2 plants of transgene-present lineages that overproduced EPSPS. We also documented significant increases in fecundity, which was associated with increased auxin content in T3 transgene-present lineages containing rice EPSPS genes, compared with their segregating transgene-absent lineages, EV, and parental controls. Our results from Arabidopsis with nine transgenic events provide a strong support to the hypothesis that transgenic plants overproducing EPSPS can benefit from a fecundity advantage in glyphosate-free environments. Stimulated biosynthesis of auxin, an important plant growth hormone, by overproducing EPSPS may play a role in enhanced fecundity of the transgenic Arabidopsis plants. The obtained knowledge is useful for assessing environmental impact caused by introgression of transgenes overproducing EPSPS from any GE crop into populations of its wild relatives.

Keywords: abiotic stress, Arabidopsis thaliana, fitness, glyphosate-tolerance, Growth Hormone, indole-3-acetic acid, seed germination, transgenic plant

Received: 15 Jan 2018; Accepted: 09 Feb 2018.

Edited by:

Andrew F. Roberts, International Life Sciences Institute, United States

Reviewed by:

Alan J. Gray, Centre for Ecology & Hydrology,Edinburgh, United Kingdom
Alan Raybould, Syngenta, Switzerland  

Copyright: © 2018 Fang, Nan, Gu, Ge, Feng and Lu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Baorong Lu, Fudan University, Shanghai, China,