Supervisors: Dr Jill Harrison and Dr Martin
Homer.
Plant shapes range from tiny string or
mat-like forms to massive multilayered upright forms with complex organ systems
such as shoots, roots and leaves. Despite these wide differences in shape, many
plant gene families are very ancient, predating shape diversification. We can
therefore study mechanisms for shape determination in simple plants such as
liverworts, and use the knowledge gained to understand plant shape
determination in general.
To this end, we previously used a
combination of live imaging, statistical model fitting, computational modelling
and molecular biology to discover mechanisms regulating shape in the liverwort Marchantia polymorpha (Solly et al.
(2017): Current Biology).
We found that Marchantia undergoes a stereotypical
sequence of shape transitions during development. The overall shape depends on regional
growth rate differences that are specified by the growing apical notches. Computational
modelling showed that a diffusible, growth-promoting cue produced in the
notches is likely to pattern these regional growth rate differences, and
pharmacological experiments suggested that the plant hormone auxin equates to this
growth-promoting cue.
New models suggest a role for differential
oriented growth (anisotropy) in Marchantia
shape determination. Anisotropy emerges as an outcome of underlying tissue
polarities, and directional auxin transport may have a role.
Your project will build on the
work above to determine how auxin contributes to plant shape determination in Marchantia.
It will:
1. Predict
the effects of different tissue polarities on Marchantia shape by modelling
2. Analyse
the auxin distribution in Marchantia and
compare it to distributions predicted by modelling
3. Disrupt
auxin biosynthesis, directional transport, conjugation and decay and test the
effect on growth and shape
4. Use
live-imaging, image segmentation and quantitative growth analyses to discover
how growth and shape change in plants with different auxin biology.
Training:
By combining computational and
wet lab approaches, your project work will provide training at the cutting edge
of the plant evolution and development fields. You will benefit from further
formal teaching and internships included in the SWBioDTP programme. The skills and
techniques you learn will be broadly applicable in the academic biology and
biotech sectors and widely transferable amongst areas such as science policy,
publishing and computing.
Reading:
Harrison
(2017). Development and genetics in the evolution of plant body plans. Philosophical Transactions of the Royal
Society B 372: 20150490.
Hong and
Roeder (2017). Plant development: differential growth rates in distinct zones
shape and ancient plant form. Current
Biology 27: R19-21.
Solly et al.
(2017). Regional growth rate differences specified by apical notch activities
regulate liverwort thallus shape. Current
Biology 27: 16-26.
Whitewoods and
Coen (2017). Growth and development of three-dimensional plant form. Current Biology 27: R910-918.
Further information:
The deadline for applications is 4th December 2017. Please contact
Dr Jill Harrison (jill.harrison@bristol.ac.uk) for informal discussions about
the project. Further information about project supervisors’ work can be found on
Jill Harrison and Martin Homers’ home pages. Further information about the SWBioDTP and application procedures is listed
on the SWBioDTP web pages.
