Mechanisms and Ecological Relevance of Direct Plant Responses to the Third Trophic Level

Project Information

PRENEMA

Grant agreement ID: 949595

DOI

10.3030/949595

Project closed

EC signature date 22 October 2020

Start date 1 January 2021

End date 30 June 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 499 671,00

EU contribution

€ 1 499 671,00

Coordinated by

UNIVERSITAET BERN
Switzerland

Periodic Reporting for period 3 - PRENEMA (Mechanisms and Ecological Relevance of Direct Plant Responses to the Third Trophic Level)

Reporting period: 2024-01-01 to 2025-06-30

Summary of the context and overall objectives of the project

Research shows that plants are able to sense the presence of predators and respond to them. The mechanisms of these responses, however, are largely unknown, including their influence on tritrophic interactions in nature. The EU-funded PRENEMA project will shed light on plant responses to the third trophic level – the natural enemies of herbivores – as a previously overlooked mechanism that controls tritrophic interactions. To do this, the project will use an interdisciplinary approach to the tritrophic model system consisting of maize and its wild ancestor teosinte, Diabrotica balteata – an insect that attacks maize roots – and its natural enemy, the nematode Heterorhabditis bacteriophora. PRENEMA's work can aid new approaches aimed at natural pest control in agriculture.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Just after mid-journey, PRENEMA advanced the technical and scientific frontiers forward as described below.

First, the PRENEMA team developed and validated of a new phenotyping platform (VolEx) that enables the simultaneous collection of root exudates and volatiles in a non-invasive manner. Using the VolEx system, we discovered that drought induced the exudation of multihexose benzoxazinoids. Because their production in plants and exact structure had previously not been fully elucidated, we isolated and characterized them through an extensive nuclear magnetic resonance study.

Second, the PRENEMA team is characterizing the plant response to entomopathogenic nematodes (EPNs). The biological responses observed were significantly more variable than initially anticipated, necessitating an increased focus on characterizing the plant exudation response to EPNs and the myriad factors influencing it. In particular, the team conducted an extensive literature review on the impact of biotic and abiotic parameters on the dynamics of plant exudation.

Moreover, as our understanding of the project's core themes has evolved, we have expanded our research scope to include additional, related aspects. These supplementary inquiries include the completion of a de novo assembly of the EPN, Heterorhabditis bacteriophora, genome and its annotation at a chromosome-scale, as well as the sequencing of 25 H. bacteriophora strains.

Third, we assessed whether the presence of EPNs in soil would affect multi trophic interactions in laboratory and field conditions. While EPNs did not affect belowground interactions, we observed that their presence in soil was sufficient to reduce the field populations of an insect pest, Ostrinia nubilalis. Further research is planned to identify the underlying mechanisms.

Overall, PRENEMA is to uncover nuanced insights into the intricate dynamics between plants and EPNs. We believe that PRENEMA will significantly contribute to the field, offering a more detailed and comprehensive understanding of tritrophic interactions.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The newly developed root exometabolome sampling system (VolEx) is an important technological step forward in the field, as no other methods were available to collect both volatile and non-volatile metabolites so far. By the end of the project, we expect to have thoroughly characterized the plant responses to entomopathogenic nematodes, their mechanisms, and relevance in agroecosystems.

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