Periodic Reporting for period 4 - VOLARE (Scentsitive nature: Green leaf volatile perception in plants and insects)
Berichtszeitraum: 2023-08-01 bis 2025-01-31
Plant leaves can emit large amounts of volatiles into the air. When attacked by insects, the composition of these blends changes markedly. It is well known that these changes affect not only the behavior of insects interacting with the plant but also the metabolism of the plant itself as well as its nearby competitors. Green leaf volatiles (GLVs) represent a group of plant volatiles emitted the earliest upon herbivory. In earlier research, we discovered a class of enzymes (hexenal isomerases), present in plants and insects, that profoundly affect ecological interactions by converting the highly abundant GLV Z-3-hexenal into E-2-hexenal. These two compounds have distinct effects on the behavior of herbivorous and predacious insects as well as on the metabolism of plants. However, how plants perceive these volatiles and generate a functional response is not known.
The key objectives of the VOLARE project are 1) to mutate plant- and insect-derived hexenal isomerases to understand the role of this enzyme for plant-insect interactions, 2) to identify the molecular mechanisms of E-2-hexenal perception in plants, and 3) to create plants and insects that cannot perceive E-2-hexenal to investigate the role of this volatile in the plant's self-recognition and its role as a signaling molecule for interactions with herbivorous insects and pathogens.
This interdisciplinary research project intends to uncover the perception mechanism of key plant volatile signals and the roles these play in the (eco)physiology of plants and insects. The outcome of this project will greatly expand the fundamental and applied research domain of plant-herbivore interactions as it allows us to perform an in-depth analysis of the biological functions and potential benefits of volatile signaling for improving agro-ecosystems.
The key objectives of the VOLARE project are 1) to mutate plant- and insect-derived hexenal isomerases to understand the role of this enzyme for plant-insect interactions, 2) to identify the molecular mechanisms of E-2-hexenal perception in plants, and 3) to create plants and insects that cannot perceive E-2-hexenal to investigate the role of this volatile in the plant's self-recognition and its role as a signaling molecule for interactions with herbivorous insects and pathogens.
This interdisciplinary research project intends to uncover the perception mechanism of key plant volatile signals and the roles these play in the (eco)physiology of plants and insects. The outcome of this project will greatly expand the fundamental and applied research domain of plant-herbivore interactions as it allows us to perform an in-depth analysis of the biological functions and potential benefits of volatile signaling for improving agro-ecosystems.
The project successfully advanced the understanding of green leaf volatile (GLV) perception and signaling in plants and insects through an integrated genetic, biochemical, and multi-omics approach.
In Work Package 1, forward genetic screens and QTL mapping in Arabidopsis thaliana led to the identification of several E-2-hexenal response (her) mutants with altered root responses to E2AL. Candidate genes involved in E2AL perception were identified using MutMap analysis, and GWAS approaches consistently revealed a QTL associated with E2AL perception.
In Work Package 2, phosphoproteomic analyses identified candidate proteins participating in E2AL signaling, which were validated through Arabidopsis T-DNA insertion mutants. These findings contributed to the functional characterization efforts in WP4.
Work Package 3 focused on the generation of insect mutants impaired in hexenal isomerase (Hi) activity using CRISPR/Cas9 technology. In the model insect Manduca sexta, CRISPR mutants provided essential insights into the role of Hi in insect physiology and development, resulting in a publication in Nature Communications. In plants, although no CRISPR lines were generated, homologs of Hi were successfully identified and cloned from diploid potato lines. Their enzymatic activity and stress-induced expression were also characterized.
Work Package 4 further investigated GLV signaling in plants. Phosphoproteomic analyses revealed rapid phosphorylation of two key proteins upon E2AL exposure. Functional studies using T-DNA insertion mutants showed altered root growth responses to E2AL, indicating a role in GLV perception and downstream signaling.
Work Package 5 explored the developmental and evolutionary significance of Hi activity in M. sexta. Multi-omics approaches revealed that Hi function affects key metabolic and hormonal pathways essential for larval development and metamorphosis. Structural and evolutionary analyses demonstrated functional convergence of Hi enzymes in plants and insects, supported by detailed phylogenetic, enzymatic, and structural evidence. These results are currently being prepared for publication.
The project has generated important genetic and biochemical resources, including Arabidopsis mutant lines and characterized potato Hi genes, along with CRISPR-edited insect lines. These tools will support future research in GLV signaling, crop protection strategies, and pest control approaches. The identification of key GLV perception components in plants opens opportunities for developing more sustainable agricultural practices by enhancing plant defense mechanisms.
Project results have been disseminated through scientific publications, including a Nature Communications article, and ongoing manuscripts. The team has also shared outcomes through conference presentations and collaborative networks, ensuring broad dissemination and potential future exploitation in applied agricultural research.
In Work Package 1, forward genetic screens and QTL mapping in Arabidopsis thaliana led to the identification of several E-2-hexenal response (her) mutants with altered root responses to E2AL. Candidate genes involved in E2AL perception were identified using MutMap analysis, and GWAS approaches consistently revealed a QTL associated with E2AL perception.
In Work Package 2, phosphoproteomic analyses identified candidate proteins participating in E2AL signaling, which were validated through Arabidopsis T-DNA insertion mutants. These findings contributed to the functional characterization efforts in WP4.
Work Package 3 focused on the generation of insect mutants impaired in hexenal isomerase (Hi) activity using CRISPR/Cas9 technology. In the model insect Manduca sexta, CRISPR mutants provided essential insights into the role of Hi in insect physiology and development, resulting in a publication in Nature Communications. In plants, although no CRISPR lines were generated, homologs of Hi were successfully identified and cloned from diploid potato lines. Their enzymatic activity and stress-induced expression were also characterized.
Work Package 4 further investigated GLV signaling in plants. Phosphoproteomic analyses revealed rapid phosphorylation of two key proteins upon E2AL exposure. Functional studies using T-DNA insertion mutants showed altered root growth responses to E2AL, indicating a role in GLV perception and downstream signaling.
Work Package 5 explored the developmental and evolutionary significance of Hi activity in M. sexta. Multi-omics approaches revealed that Hi function affects key metabolic and hormonal pathways essential for larval development and metamorphosis. Structural and evolutionary analyses demonstrated functional convergence of Hi enzymes in plants and insects, supported by detailed phylogenetic, enzymatic, and structural evidence. These results are currently being prepared for publication.
The project has generated important genetic and biochemical resources, including Arabidopsis mutant lines and characterized potato Hi genes, along with CRISPR-edited insect lines. These tools will support future research in GLV signaling, crop protection strategies, and pest control approaches. The identification of key GLV perception components in plants opens opportunities for developing more sustainable agricultural practices by enhancing plant defense mechanisms.
Project results have been disseminated through scientific publications, including a Nature Communications article, and ongoing manuscripts. The team has also shared outcomes through conference presentations and collaborative networks, ensuring broad dissemination and potential future exploitation in applied agricultural research.
Our goal is to deliver the first non-hormone-related plant receptor for one or more volatile metabolites and to create a rich collection of tools (e.g. mutant plants and insects) that can be used to study how information encrypted in volatile signals is processed by plants. We also aim to gain insight into the robustness of information exchange via such signals and the consequences of signal promiscuity across different trophic levels. Understanding the perception mechanism of non-hormonal plant volatiles, such as E-2-hexenal, could fundamentally change our view on how plants exchange information with their environment.