Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2-keto-4-methylthiobutyric acid production

PLoS Genet. 2018 Mar 19;14(3):e1007273. doi: 10.1371/journal.pgen.1007273. eCollection 2018 Mar.


Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production. Studying the SA187 interaction with Arabidopsis, we uncovered a number of mechanisms related to the beneficial association of SA187 with plants. SA187 colonizes both the surface and inner tissues of Arabidopsis roots and shoots. SA187 induces salt stress tolerance by production of bacterial 2-keto-4-methylthiobutyric acid (KMBA), known to be converted into ethylene. By transcriptomic, genetic and pharmacological analyses, we show that the ethylene signaling pathway, but not plant ethylene production, is required for KMBA-induced plant salt stress tolerance. These results reveal a novel molecular communication process during the beneficial microbe-induced plant stress tolerance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological*
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology
  • Arabidopsis / physiology*
  • Enterobacter / physiology*
  • Ethylenes / metabolism*
  • Gene Expression Regulation, Plant
  • Methionine / analogs & derivatives*
  • Methionine / biosynthesis
  • Methionine / metabolism
  • Plant Roots / metabolism
  • Plant Shoots / metabolism
  • Potassium / metabolism
  • Stress, Physiological*


  • Ethylenes
  • 2-keto-4-methylthiobutyric acid
  • ethylene
  • Methionine
  • Potassium

Grant support

This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST), base fund for HH no. BAS/1/1062-01-01. For ER, this publication has been written with the support of the Agreenskills fellowship programme which has received funding from the EU’s Seventh Framework Programme under grant agreement N° FP7-609398 (Agreenskills+ contract). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.