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Braybrook Group

Siobhan Braybrook

Career Development Fellow

Sainsbury Laboratory Cambridge
University of Cambridge
Bateman Street

Cambridge CB2 1LR

Office Phone01223 761146

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Research Interests

The mechanics of plant growth

In all organisms, the growing of a shape is a complex process requiring specific gene products, signaling, mechanical alterations, and coordination of cell growth. Our Team addresses this fundamental process in biology using a multidisciplinary approach including: plant physiology, biochemistry, genetics, molecular biology, materials science, and physics.

For a plant cell, the cell wall is the main structural element, controlling shape and growth of the cell and therefore tissue as a whole. Recent work in plants has correlated key aspects of organ growth and shape generation with mechanical properties of tissues and cell walls. Our Team has two main goals: 1) to understand the mechanics of shape growth in plants, and 2) to understand the cell wall as a dynamic composite material.

The mechanics of shape growth in plants

We utilize many different plant species and growth systems to understand how plants grow shapes. From mersitems to hypocotyls, roots, and leaves; drawn from species like tomato, tobacco, maize, moss, sunflower, and Arabidopsis.

Our first aim is to understand, on a simple level, the changes in cell mechanics associated with cell growth. This work is being done in Tobacco BY-2 cells and Arabidopsis protoplasts after wall regeneration. Our further aims centre on describing complex shape growth such as organ formation at shoot meristems (Arabidopiss, maize, sunflower), and anisotropic growth in stems and leaves (Arabidopsis, maize, tomato).

We also aim to describe the molecular-mechanical aspects of the growth of other plant cells, tissues, and organs. We link mechanical changes in the cell wall that regulate growth, to biochemical changes and their control by hormones and gene products. Using this multidisciplinary approach, we hope to begin understanding the mechanical changes associated with the complex shapes grown in nature.

The cell wall as material

The cell wall is an incredibly complex material. In the most basic terms it is a fibre re-enforced gel; however, its structure is dynamic and elusive.  We aim to understand how the material properties of the cell wall components, and emergent composite behaviours, relate to its shifting mechanical functions during growth. Understanding this beautiful material shaped by evolution will allow us to understand growth but also provide inspirations for synthetic materials.

We utilize Tobacco BY-2 cells, cell wall mimics, and individual cell wall components to literally untangle the mechanical nature of the plant cell wall material.

Key Publications

Selected Recent Publications

SA Braybrook, A Peaucelle (2013) Mechano-Chemical Aspects of Organ Formation in Arabidopsis thaliana: The Relationship between Auxin and Pectin. PLoS ONE 8(3): e57813. doi:10.1371/journal.pone.0057813

DH Chitwood, LR Headlan1, ARanjan, SA Braybrook, DP Koenig, C Martinez, C Kuhlemeier, RS Smith, and NR Sinha. 2012. Leaf asymmetry as a developmental constraint imposed by auxin-dependent phyllotactic patterning. The Plant Cell. 24:1-10.

A Peaucelle*, SA Braybrook*, L Le Guillou, E Bron, C Kuhlemeier, H Hofte. 2011. Pectin-Induced Changes in Cell Wall Mechanics Underlie Organ Initiation in Arabidopsis.Current Biology. Online Oct. 6th. *Co-first authors

SL Stone, SA Braybrook, SL Paula, LW Kwong, J Meuser, J Pelletier, T-F Hsieh, RL Fischer, RB Goldberg, JJ Harada. 2008. Arabidopsis LEAFY COTYLEDON2 Induces Maturation Traits and Auxin Activity: Implications for Somatic Embryogenesis. Proc Natl Acad Sci USA. 105:3151-3156.

SA Braybrook, SL Stone, S Park, AQ Bui, BH Le, RL Fischer, RB Goldberg, JJ Harada. 2006. Genes directly regulated by LEAFY COTYLEDON2 provide insight into the control of embryo maturation and somatic embryogenesis. Proc Natl Acad Sci USA . Feb 28;103(9):3468-73.

Recent Review Publications

SA Braybrook. 2014. Signalling in plant cell patterning- mechano-molecular theory and phyllotaxis. In: The Biochemist. Special Issue: Signalling in Plants and Microbes

P Milani, SA Braybrook, A Boudaoud. 2013. Shrinking the hammer: micromechanical approaches to morphogenesis. Journal of Experimental Botany. (first published online July 19, 2013) 

SA Braybrook, H Hofte, A Peaucelle. 2012. Probing the mechanical contributions of the pectin matrix: insights for cell growth. Plant, Signaling, and Behavior. 7(8):45-46.

A Peaucelle, SA Braybrook, H Hofte. 2012. Cell wall mechanics and growth control in plants: the role of pectins revisited. In: Frontiers in Plant Physiology, Research Topic: Current challenges in plant cell walls. Volume 3, article No. 121.

SA Braybrook and C Kuhlemeier. How a plant builds leaves. 2010. The Plant Cell. 22: 1006-1018.

A confocal images of cell walls (left) used to make a cell volume map of an etiolating Arabidopsis hypocotyl (center). An elastic modulus map of a similar hypocotyl base (right).

An elastic modulus map of a maize floral meristem, as determined with AFM. Yellow regions are more rigid than red regions. The growing lemma displays more elastic cell walls

A 12 hour growth map of an Arabidopsis inflorescence meristem. Cell area increase are colored from blue to red.

 

Research supported by: