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Cellular development and evolution in plants.
Research in our group uses multidisciplinary approaches to investigate mechanisms controlling plant growth and development with emphasis on the evolution of regulatory mechanisms.
Morphological Evolution in Land Plants
The colonization of the land by multicellular, photosynthetic, eukaryotes some time before 470 million years ago led dramatically changed the Earth. This spread of green plants to the dry continental surfaces was accompanied by the evolution of suite of morphological novelties. The development of rooting systems – simple and unicellular in the earliest colonizers but complex axes with complex tissue organization in later diverging groups – gave the plants access to water, mineral nutrients and interface with the microbes in the earliest soils.
A major aim of our research is to understand the evolution of the rooting structures in first land plants. Specifically we use comparative developmental genetics to identify genes that regulate rooting structure development in early diverging and late diverging groups of land plants. Identifying genes that are common to both groups of organisms defines a minimal set of genes that were active in the last common ancestor of the land plants. This minimal gene set defines the mechanism that evolved at or soon after the colonization of the land.
This analysis has discovered that a core set of genes controlling the development of specialized unicellular and multicellular structures derived from single epidermal cells in the last common ancestor of the land plants. Future research will investigate the cell biology of epidermal morphogenesis, symmetry breaking, cell polarity and the role of the cell wall in defining cell shape and cellular integrity. This builds on the genetic tools that we are developing in early diverging land plants in combination with genomics, imaging and modeling to build a coherent model for morphogenesis of complex structures in the first land plants.
Root Hair Development
Root hairs are tip-growing cells develop on the surface of roots. These filamentous structures play important roles in nutrient absorption, water uptake and anchorage required for plant growth and establishment. Using genetic analysis discovered novel mechanisms controlling root hair development. For example, we discovered that the differentiation of root hairs requires the activity of a conserved group of basic helix loop helix transcription factors that promote the expression of genes encoding proteins required for growth. One of these transcription factors – RSL4 – is necessary and sufficient for root hair growth. The final size of root hairs is determined by the intensity of a pulse of RSL4 protein that is synthesized just before root hair initiation. Future research will define how RSL4 modulates cell size and how RSL4 is itself regulated.
Root Development in Grasses and Cereals
Root hairs play key roles as rooting function in food and forage crops. To understand how modifying root hair traits are controlled in these crops, we investigate the genetics of root hair development in cereals and grasses. We are characterizing the function of RSL genes in cereal crops (rice and wheat) and the wheat relative, Brachypodium distachyon. We are also developing partnerships and collaborations to exploit this opportunity in forage crops. These analyses will provide genetic understanding of the regulation of these important agronomic traits and will also allow us to obtain proof of concept data that will contribute to future crop breeding programs.
Fossil Rooting Systems
Fossils provide unique morphological information about organisms that are long extinct. We are characterizing fossils to define the structure and development of some of the most enigmatic plants that grew between 280 and 360 million years ago. Coal balls – nodules of calcium carbonate containing fossilized peaty soil from coal swamps – contain fossil roots. The cellular detail of these fossils has been exquisitely preserved and allows us to define the fine detail of some of the first early complex roots. It also allows us to investigate the cellular events that occurred during the organogenesis of these roots. The use of fossils to understand long-extinct diversity complements our use of genetics and genomics to discover mechanisms that underpinned the evolution of some of the first complex rooting systems.
We use our fundamental discoveries to develop technologies for the bio-industry. If you are interested in any technologies that emerge from our fundamental research contact us at email@example.com.
Publications since 2015
- Proust H, Honkanen S, Jones V, Morieri G, Prescott H, Kelly S, Ishizaki K, Kohchi T, Dolan L 2016 RSL class I genes controlled the development of epidermal structures in the common ancestor of land plants Current Biology 26, 93–99 doi:10.1016/j.cub.2015.11.042
- Ortiz-Ramírez C, Hernandez-Coronado M, Thamm A, Catarino B, Wang M, Dolan L, Feijo J, Becker J 2016 A comprehensive Physcomitrella patens transcriptome atlas provides insights into the evolution and development of land plants Molecular Plant doi:10.1016/j.molp.2015.12.002
- Datta S, Prescott, H, Dolan L 2015 The intensity of a pulse of transcription factor synthesis controls cell size Nature Plants 1, 15138 doi:10.1038/nplants.2015.138
- Tam T, Catarino B, Dolan L 2015 A conserved regulatory mechanism controls rooting cell development in land plants Proceedings of the National Academy of Sciences USA 112, 3959–3968 doi:10.1073/pnas.1416324112
- Romeu-Dalmau C, Bonsall, MB, Willis KJ, Dolan L 2015 Asiatic cotton can generate similar economic benefits to Bt cotton under rainfed conditions Nature Plants 1, 15072 doi:10.1038/nplants.2015.72
- Saint-Marcoux D, Proust H, Dolan L, Langdale JA 2015 Identification of reference genes for real-time quantitative PCR experiments in the liverwort Marchantia polymorpha PLoS One doi:10.1371/journal.pone.0118678
Ten Selected Publications
- Pires ND, Keke Y, Breuninger H, Catarino B, Menand B, Dolan L 2013 Recruitment and remodeling of an ancient gene regulatory network during land plant evolution Proceedings of the National Academy of Sciences USA 110, 9571–90576 doi:10.1073/pnas.1305457110
- Lenton TM, Crouch M, Johnson M, Pires N, Dolan L 2012 First plants cooled the Ordovician Nature Geoscience 5, 86–89 doi:10.1038/ngeo1390
- Jang G, Pires N, Keke Y, Menand B, Dolan L 2011 RSL genes are sufficient for rhizoid system development in early diverging land plants Development 138, 2273–2281 doi:10.1242/dev.060582
- Pernas-Ochoa M, Ryan E, Dolan L 2010 SCHIZORHIZA controls tissue system complexity in plants Current Biology 20, 818–823 doi:10.1016/j.cub.2010.02.062
- Keke Y, Bell E, Menand B, Dolan L 2010 A basic helix loop helix transcription factor controls cell growth and size in root hairs Nature Genetics 42, 264–267 doi:10.1038/ng.529
- Pires ND, Dolan L 2010 Origin and diversification of basic helix-loop helix proteins in plants Molecular Biology and Evolution 27, 862–874 doi:10.1093/molbev/msp288
- Saint Savage N, Walker T, Panciera Y, Schiefelbein J, Dolan L, Monk NAM 2008 Mutual support of alternative cell fates through the directed movement of CAPRICE and GLABRA3 provides a novel mechanism for patterning the Arabidopsis root epidermis PLoS Biology 6, e235 doi: 10.1371/journal.pbio.0060235
- Takeda S, Gapper C, Kaya H, Bell E, Kuchitsu K, Dolan L 2008 Local positive feedback regulation determines cell shape in root hair cells Science 319, 1241–1243 doi:10.1126/science.1152505
- Ortega-Martinez O, Pernas-Ochoa M, Carol R, Dolan L 2007 Ethylene modulates stem cells division in the Arabidopsis thaliana root. Science 317, 505–510 doi:10.1126/science.1143409
- Menand B, Keke Y, Jouannic S, Hoffmann L, Ryan E, Linstead P, Schaefer DG, Dolan L 2007 An ancient mechanism controls the development of cells with a rooting function in land plants Science 316, 1477–1480 doi:10.1126/science.1142618