New research on why plant tissues have a sense of direction
Scientists at the John Innes Centre, Norwich have published new evidence that plant tissues can have a preferred direction of growth and that this characteristic is essential for producing complex plant shapes.
The work, carried out by Dr Alexandra Rebocho and colleagues in Professor Enrico Coen's laboratory, contributes a new piece to the puzzle of how plant shapes are formed, and could have wide implications on our understanding of shape formation, or 'morphogenesis', in nature. Improved understanding of how genes influence plant shape formation could inform research into crop performance and lead to better-adapted, higher yield crop varieties.
The pioneering research, published in eLife, required an integrative approach, using diverse techniques including computer modelling, 3D-imaging, fluorescence imaging and a range of genetic techniques.
Plant organs, such as leaves, petals, and fruits, each start out as a tiny ball of cells that grow into a specific final shape. The precise shape of these organs has been modified over millions of years of evolution in relation to specific functions such as attracting pollinators or catching sunlight.
One of the prevailing theories of how complex plant shapes develop, upon which this new research builds, is the theory of 'tissue conflict resolution'. At the heart of shape development are internal differences in how tissue regions grow, and it is the resolution of these conflicts that produces shapes. These tissue conflicts are not contentious, but precisely coordinated, with their resolution leading to a particular flower or leaf shape.
Within the 'tissue conflict resolutions' theory, growth outcomes depend on groups of cells, called tissues. In isolation, individual regions of tissue would simply grow equally in all directions, or elongate in a preferred direction.
In reality, tissue regions do not occur in isolation. The adhesion and cohesion between adjoining regions, each following their own growth patterns, creates stresses, which cause the tissues to buckle, curve or bend to a compromise state.
These three-dimensional, out-of-plane tissue deformations are found extensively within the plant and animal kingdoms, and underlie some critical processes of animal development, including gut folding, neurulation, and development of the cerebral cortex.
There are three proposed types of tissue conflict resolution: areal, surface and directional. Areal conflict is between two areas of tissue within a surface, and surface conflicts occur between adjoining, but distinct, surfaces. Both areal and surface conflicts have been previously shown to be important for shape development.
The new paper, published today in eLife, provides evidence for the third category: directional conflict. Tissues, or collections of tissues, can have a set of directions, or 'polarity field', caused by asymmetrical distribution of proteins within cells. Tissue regions may respond to this directionality, i.e. grow faster parallel or perpendicular to the local polarity field.
Much like surface and areal conflicts, adjoining tissues with differing specified directions of growth will lead to conflicts. When combined, resolution of the three types of conflict can produce vastly diverse and complex shapes.
This research moves us one step closer to understanding how genes can influence the remarkably intricate and beautiful plant shapes we see all around us.
This research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).
Notes to editors
1. The paper 'Generation of shape complexity through tissue conflict resolution' can be found at https://elifesciences.org/content/6/e20156
2. Images to accompany the press release can be downloaded from: http://bit.ly/2lf7Skk
3. If you would like to interview Professor Coen please contact:
Geraldine Platten, Acting Head of External Relations
The John Innes Centre
4. About the John Innes Centre
The John Innes Centre is an independent, international centre of excellence in plant science and microbiology.
Our mission is to generate knowledge of plants and microbes through innovative research, to train scientists for the future, to apply our knowledge of nature's diversity to benefit agriculture, the environment, human health and wellbeing, and engage with policy makers and the public.
To achieve these goals we establish pioneering long-term research objectives in plant and microbial science, with a focus on genetics. These objectives include promoting the translation of research through partnerships to develop improved crops and to make new products from microbes and plants for human health and other applications. We also create new approaches, technologies and resources that enable research advances and help industry to make new products. The knowledge, resources and trained researchers we generate help global societies address important challenges including providing sufficient and affordable food, making new products for human health and industrial applications, and developing sustainable bio-based manufacturing.
This provides a fertile environment for training the next generation of plant and microbial scientists, many of whom go on to careers in industry and academia, around the world.
The John Innes Centre is strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC). In 2015-2016 the John Innes Centre received a total of £30.1 million from the BBSRC.
The John Innes Centre is also supported by the John Innes Foundation through provision of research accommodation and long term support of the Rotation PhD programme.
The John Innes Centre is the winner of the BBSRC's 2013 – 2016 Excellence With Impact award.
5. About the BBSRC
The Biotechnology and Biological Sciences Research Council (BBSRC) invests in world-class bioscience research and training on behalf of the UK public. Our aim is to further scientific knowledge, to promote economic growth, wealth and job creation and to improve quality of life in the UK and beyond.
Funded by Government, BBSRC invested over £473M in world-class bioscience in 2015-16. We support research and training in universities and strategically funded institutes. BBSRC research and the people we fund are helping society to meet major challenges, including food security, green energy and healthier, longer lives. Our investments underpin important UK economic sectors, such as farming, food, industrial biotechnology and pharmaceuticals.
For more information about BBSRC, our science and our impact see: http://www.bbsrc.ac.uk
For more information about BBSRC strategically funded institutes see: http://www.bbsrc.ac.uk/institutes