Skip to main content

ORIGINAL RESEARCH article

Front. Plant Sci.
Sec. Plant Abiotic Stress
Volume 15 - 2024 | doi: 10.3389/fpls.2024.1488671

Humic substances increase tomato tolerance to osmotic stress while modulating vertically-transmitted endophytic bacterial communities

Provisionally accepted
Salomé Lengrand Salomé Lengrand 1,2*Benjamin Dubois Benjamin Dubois 3Lena Pesenti Lena Pesenti 1,2Frederic Debode Frederic Debode 3Legreve Anne Legreve Anne 1,2*
  • 1 Earth and Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Walloon Brabant, Belgium
  • 2 Applied Microbiology (ELIM), Louvain-la-Neuve, Belgium
  • 3 Walloon Agricultural Research Centre, Gembloux, Namur, Belgium

The final, formatted version of the article will be published soon.

    While humic substances (HS) are recognized for their role in enhancing plant growth under abiotic stress by modulating hormonal and redox metabolisms, a key question remains: how do HS influence the microbiota associated with plants? This study hypothesizes that the effects of HS extend beyond plant physiology, impacting the bacterial endophytic community. To explore this, we investigated the combined and individual impacts of HS and osmotic stress on tomato plant physiology and roots endophytic communities. Tomatoes were grown within a sterile hydroponic system which allowed to focus on seed-transmitted endophytic bacteria. Moreover, sequencing the 16S-ITS-23S region of the rrn operon (˜4,500 bp) in a metabarcoding assay using the PNA-chr11 clamp nearly eliminated reads assigned to Solanum lycopersicum and allowed species-level identification of these communities. Our findings revealed that HS, osmotic stress and their combined application induce changes in bacterial endophytic communities.Osmotic stress led to reduced plant growth and a decrease in Bradyrhizobium sp., while the application of HS under osmotic stress resulted in increased tomato growth, accompanied by an increase in Frigoribacterium sp., Roseateles sp., and Hymenobacter sp., along with a decrease in Sphingomonas sp. Finally, HS application under non-stress conditions did not affect plant growth but did alter the endophytic community, increasing Hymenobacter sp. and decreasing Sphingomonas sp. This study enhances understanding of plant-endophyte interactions under stress and HS application, highlighting the significance of the verticallytransmitted core microbiome in tomato roots and suggesting new insights into the mode of action of HS used as biostimulant.

    Keywords: Humic acids, Fulvic acids, Drought stress, Seed-borne endophytes, Plant-endophyte interactions, endophytome composition, Solanum lycopersicum, Hydroponics

    Received: 30 Aug 2024; Accepted: 16 Oct 2024.

    Copyright: © 2024 Lengrand, Dubois, Pesenti, Debode and Anne. 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) or licensor 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:
    Salomé Lengrand, Earth and Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, 1348, Walloon Brabant, Belgium
    Legreve Anne, Applied Microbiology (ELIM), Louvain-la-Neuve, Belgium

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.