Frontier Leaders Seminar

Title: Development and evolution of land plant rooting systems

Speaker: Liam Dolan

Affiliation: Department of Plant Sciences, University of Oxford, UK

Abstract

The evolution of the first rooting systems some time before 400 million years was a key innovation that occurred when the first complex multicellular eukaryotic photosynthetic organisms – plants – colonized the land.  The rooting systems of the earliest diverging group of extant land plants comprised unicellular tip-growing filaments called rhizoids and are morphologically similar to cells that develop at the interface between the plant and the soil in vascular plants – root hairs.   Subsequently specialized axes – multicellular structures that are covered in tip-growing cells that develop from self-renewing populations of cells called meristems (roots) – evolved that carry out rooting function.

A major aim of our research is to use fossils and genes and to understand key events in the evolution of land plant rooting systems.  Fossils demonstrate the variety of forms that existed and how these forms developed.  By characterising the development of plants preserved in fossils we showed that root evolution progressed in a step-wise fashion, where different structural elements progressively accumulated over time.  Identification of genes through mutant screens in diverse organisms has defined key elements in the regulatory mechanism that controlled the development of the first land plant root system.  Comparing the functions of genes in diverse land plant lineages demonstrates how this mechanism changed during the course of evolution. We found that a positive regulatory mechanism that promotes rooting structure development is preserved in most land extant plant lineages.  By contrast, negative regulatory components of the mechanism evolved independently in different lineages.  I will present recent, unpublished data on the role of a negative regulator in the patterning of rhizoids in the liverwort Marchantia polymorpha.  These new data demonstrate how model systems can be used to discover new fundamental mechanism of development as well as highlighting how ancient mechanism evolved during the course of land plant evolution.

Bio

Liam grew up in Dublin and got an undergraduate degree at University College, Dublin (UCD).  He carried out PhD research at the University of Pennsylvania, was a PI at the John Innes Centre and has been Professor of Botany at Oxford University since 2009.  Liam’s research group uses genetics to discover molecular mechanisms that control plant development.  He is a member of the European Molecular Biology Organisation and a Fellow of the Royal Society and serves as a Trustee of the Royal Botanic Garden Kew.