Variation on a theme: evolutionary-developmental insights into the Asteraceae flower head.
Plant reproduction relies on flowers and their arrangement into an inflorescence – two interrelated traits that exhibit impressive variation between plant lineages. CAPITULA focuses on this floral architecture, which has been central to angiosperm diversification and also has implications for increasing crop yields and alowing development of horticultural forms. A key aim in evolutionary biology is to unravel how the modification of genetic networks has led to the diversification of reproductive plant architecture and floral form. This project addresses this aim by seeking to understand how two fundamental biological processes, floral architecture and symmetry, have evolved in the daisy family Asteraceae, with unique combinations of these traits.
Much of the research on Asteraceae, one of the largest families of flowering plants, has concentrated on model plant systems with simple heterogamous capitula (e.g. gerbera, sunflower). We propose a novel evolutionary-developmental (evo-devo) approach to floral evolution, by bringing to this field the species of Asteraceae with secondary heads (=syncephalia). This unique capitulum architecture has arisen from two rounds of capitulescence (i.e. inflorescence condensation followed by simplification) during their evolution.
Syncephalous species, which comprise about 70 genera from 11 tribes, provide an invaluable source of material for deciphering the genetic basis of capitulum evolution since their genomes bear the signature of two inflorescence shifts toward capitulescence. Our approach, integrating the most recent experimental and theoretical developments in the evo-devo and genomics fields, provides a unique opportunity to ask fundamental questions relating to coordinated trait evolution, and to increase our understanding of how genetic pathways have been altered or co-opted during the evolutionary diversification of flowers.
The knowledge gained from this project has the potential to open up novel molecular breeding strategies for developing improved varieties of horticultural and crop plants in this family of great economic importance (e.g. artichoke, chrysanthemum, gerbera, knapweeds, lettuce, sunflower). Given the economic and ecological importance of Asteraceae, data generated from this project will also be essential for increasing our understanding of how they contribute to ecosystem services and their management. In addition, the majority of syncephalous Asteraceae genera comprise a single species, meaning that global change could lead to rapid erosion of diversity at the genus level. By focusing the light on syncephalous Asteraceae, CAPITULA contributes to assessing the threat status of syncephalous species and establishing conservation policies to protect them.
This project is structured into three parts, each focused on a different research aspect of the topic:
- Exploring the morphological landscape of Asteraceae syncephalia: What is the biological and evolutionary significance of capitulum diversification in Asteraceae?
- Identifying the origin and assembly of the genetic pathways associated with inflorescence transitions: Is the same genetic pathway repeatedly recruited to specify the capitulum and the syncephalia?
- The hidden face of genomics: Have repetitive DNA sequences –and more particularly transposable elements– played a role in the evolution of capitula and syncephalia?
- Production of typology and dated phylogenetic framework for syncephalous Asteraceae.
- Increased understanding of evolutionary diversity and genomic processes underlying trait evolution in Asteraceae, one of the most species-rich families of angiosperms.
- Generation of data useful for assessing the threat status of syncephalous species and establishing conservation policies to protect them.
- Increased understanding of how Asterceae contribute to ecosystem services and their management.
- University of Cambridge
- University of Helsinki, Finland
- Institute of Plant Molecular Biology, Czech Republic
- Museo Argentino de Ciencias Naturales, Argentina
- University Paris XI, France
- Smithsonian National Museum of Natural History, USA
- Institut Botànic de Barcelona/Universitat de Barcelona, Spain
Marie Sklodowska-Curie Action program (CAPITULA – grant agreement n°657918)