Community Research and Development Information Service - CORDIS


CarnoMorph Report Summary

Project ID: 323028
Funded under: FP7-IDEAS-ERC
Country: United Kingdom

Final Report Summary - CARNOMORPH (The Evolution and Development of Complex Morphologies)

A new model system, the carnivorous plant Utricularia gibba, has been developed to unravel some of the principles by which 3D shapes arise during development. Utricularia has aquatic cup-shaped leaves with closed lids, which provide suction traps to capture small animals. The trap structure is thought to have evolved through modification of leaf development, but how this happened is unclear. New methodologies were developed to allow this problem to be tackled in Utricularia, including genetic transformation, localisation of gene expression, mutagenesis, genetics, genomic analysis, induction of gene activity, imaging and computational modelling of 3D cellular development. The results show that genes involved in establishing early asymmetries in plants with typical leaves, such as Arabidopsis, are expressed in a novel pattern in early Utricularia primordia and establish domains that presage the layered organisation of the traps. Inducing these genes to be active in all cells at early stages, causes primordia to switch from trap to leaf development, showing that these genes play a key role in establishing the identity and development of these structures. By following the development of traps through later stages, key transitions in shape were identified, from an initial near-spherical form to a flattened disc with extended midline. Through computational modelling of tissue and cellular growth, hypotheses were developed to account for the observed changes in shape though conflicts in rates and orientations of growth. Predictions of these hypotheses were tested by introducing fluorescent markers to quantify the cell sizes and shapes of the trap during different stages of development, and induce cells to switch markers on at particular stages and follow their descendants. The experimental data supports a hypothesis in which a field of cell polarities, in which each cell has an internal arrow or asymmetry, orients the growth of the tissue. This idea was further supported through 3D analysis of cellular glands in the wall of the traps, which revealed a pattern of arrows as predicted. The pattern of development is under genetic control, as revealed by isolation of mutants with altered trap shapes, and demonstration that these can be mapped to individual genes.
Taken together, these findings show that the complex 3D leaf shapes arise through altered activity of genes involved in establishing leaf asymmetries which modify the pattern of oriented growth, providing an evolutionarily flexible system for generating a great diversity of forms.

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United Kingdom
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