March 2020

Heribert Hirt - Reprogramming of host and microbe metabolisms during beneficial plant-microbe interaction

  • Date: Mar 4, 2020
  • Time: 14:00 - 15:30
  • Location: Central Building
  • Room: Seminar Room
  • Host: Friedrich Kragler

Beneficial microbes can enhance plant growth and provide abiotic and biotic stress tolerance to plants, but their underlying mechanisms are poorly understood. Enterobacter sp. SA187 is a root endophytic bacterium that maintains growth and yield of various monocot and dicot plants under various abiotic stress conditions. We compared the metabolic wirings of Arabidopsis and SA187 in the free-living and endophytic states. Upon plant interaction, massive changes in bacterial gene expression in chemotaxis, flagellar biosynthesis, quorum sensing and biofilm formation were observed. In both plant and bacteria, carbon, energy and sulfur metabolisms were modified. The importance of the S metabolism in plant salt stress was substantiated by observing that several sulfur metabolism mutants show hypersensitivity to salt stress which can be partially rescued by SA187. Moreover, salt stress-induced ROS accumulation i n Arabidopsis was suppressed by SA187 in wild type and mutants of LSU2, a central chloroplast regulator linking sulfur metabolism to SOD activity. Sulfur levels in chloroplasts are monitored by the FRY1/SAL1 retrograde signaling pathway, mutants of which can also be partially rescued by SA187. We showed that SA187 provides a small sulfur metabolite to its host plant which regulates the ethylene signaling pathway. Our data are consistent with the model that plant salt stress tolerance is mediated by ethylene regulated sulfur metabolism and that chloroplast retrograde signaling might play an important role during beneficial plant-microbe interaction.

References:

  • de Zelicourt A, Al-Yousif M, Hirt H.(2013) Rhizosphere microbes as essential partners for plant stress tolerance. Mol Plant 6:242-5.
  • Andrés-Barrao C, Lafi FF, Alam I, de Zélicourt A, Eida AA, Bokhari A, Alzubaidy H, Bajic VB, Hirt H, Saad MM. (2017) Complete Genome Sequence Analysis of Enterobacter sp. S A187, a Plant Multi-Stress Tolerance Promoting Endophytic Bacterium.Front Microbiol. 8:2023
  • de Zélicourt A, Synek L, Saad MM, Alzubaidy H, Jalal R, Xie Y, Andrés-Barrao C, Rolli E, Guerard F, Mariappan KG, Daur I, Colcombet J, Benhamed M, Depaepe T, Van Der Straeten D, Hirt H. (2018) Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2-keto-4-methylthiobutyric acid production. PLoS Genet. 14(3):e1007273.
 
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