The N-acyl homoserine-lactone depleted Rhizobium radiobacter mutant RrF4NM13 shows reduced growth-promoting and resistance-inducing activities in mono- and dicotyledonous plants

Ibrahim Alabid, Martin Hardt, Jafargholi Imani, Anton Hartmann, Michael Rothballer, Dan Li, Jenny Uhl, Philippe Schmitt-Kopplin, Stefanie Glaeser, Karl Heinz Kogel

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The Alphaproteobacterium Rhizobium radiobacter (syn. Agrobacterium tumefaciens, “A. fa brum”) can live in close association with the sebacinoid fungus Serendipita (syn. Piriformospora) indica that forms a mutualistic Sebacinalean symbiosis with a wide range of host plants. The endobacterial strain R. radiobacter F4 (RrF4), which was originally isolated from the fungus, has plant growth promotion and resistance-inducing activities resembling the beneficial activities known from the endobacteria-containing S. indica. The mechanism by which free endobacterial cells influence growth and disease resistance of colonized host plants is not fully understood. Here, we show that RrF4 produces a spectrum of quorum sensing-mediating N-acyl-homoserine lactones (AHLs) with acyl chains of C8, C10, and C12 as well as hydroxyl- or oxo-substitutions at the C3 position. In addition, and in line with previous findings showing that AHLs increase plant biomass and induce systemic resistance, the AHL-depleted lactonase-overexpressing transconjugant RrF4NM13 was partially compromised in promoting growth and inducing resistance against bacterial pathogens in both Arabidopsis thaliana and wheat (Triticum aestivum). Scanning and transmission electron microscopy proved that RrF4NM13, in contrast to RrF4, does not form cellulose-like fiber scaffolds for efficient root surface attachment. Moreover, RrF4NM13 does not penetrate into the intercellular space of the cortical tissue, which in contrast is strongly colonized by RrF4. We discuss the possibility that AHLs contribute to the outcome of the Sebacinalean symbiosis.

Original languageEnglish
Pages (from-to)769-781
Number of pages13
JournalJournal of Plant Diseases and Protection
Volume127
Issue number6
DOIs
StatePublished - 1 Dec 2020
Externally publishedYes

Keywords

  • Homoserine lactones
  • Piriformospora
  • Pseudomonas
  • Quorum sensing
  • Rhizobium

Fingerprint

Dive into the research topics of 'The N-acyl homoserine-lactone depleted Rhizobium radiobacter mutant RrF4NM13 shows reduced growth-promoting and resistance-inducing activities in mono- and dicotyledonous plants'. Together they form a unique fingerprint.

Cite this