Nodulation and nitrogen fixation in Medicago truncatula strongly alters the abundance of its root microbiota and subtly affects its structure

Environ Microbiol. 2022 Nov;24(11):5524-5533. doi: 10.1111/1462-2920.16164. Epub 2022 Aug 31.


The plant common symbiosis signalling (SYM) pathway has shared function between interactions with rhizobia and arbuscular mycorrhizal fungi, the two most important symbiotic interactions between plants and microorganisms that are crucial in plant and agricultural yields. Here, we determine the role of the plant SYM pathway in the structure and abundance of the microbiota in the model legume Medicago truncatula and whether this is controlled by the nitrogen or phosphorus status of the plant. We show that SYM mutants (dmi3) differ substantially from the wild type (WT) in the absolute abundance of the root microbiota, especially under nitrogen limitation. Changes in the structure of the microbiota were less pronounced and depended on both plant genotype and nutrient status. Thus, the SYM pathway has a major impact on microbial abundance in M. truncatula and also subtly alters the composition of the microbiota.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Gene Expression Regulation, Plant
  • Medicago truncatula* / genetics
  • Medicago truncatula* / metabolism
  • Medicago truncatula* / microbiology
  • Microbiota* / genetics
  • Mycorrhizae* / genetics
  • Mycorrhizae* / metabolism
  • Nitrogen / metabolism
  • Nitrogen Fixation / genetics
  • Plant Proteins / metabolism
  • Plant Root Nodulation / genetics
  • Plant Roots / microbiology
  • Symbiosis / genetics


  • Plant Proteins
  • Nitrogen