Western Australia
June 27, 2007
Ground-breaking research into the
link between seed growth and smoke has secured plant biologist
Dave Nelson a trip to Mexico.
Dr Nelson, a researcher at the Australian Research Council (ARC)
Centre of Excellence
in Plant Energy Biology, at
The University of Western Australia, is investigating how it
is that some plant seeds are triggered to germinate after
exposure to smoke.
His innovative work on a novel group of natural compounds that
play a role in regulating plant development has earned him
funding to present his research findings at the next
International Plant Growth Substance Association conference in
Puerto Vallarta, Mexico, from July 21 to 25, 2007, an event held
once every three years.
Dr Nelson said fires played a major role in shaping the
Australian bush.
“Even though the landscape looks devastated to us after a
bushfire, it is quickly covered by a flush of new growth,” he
said.
“For the seeds of many native Australian species, the smoke from
a fire is the trigger to wake up and take advantage of the newly
available resources. Understanding this phenomenon could have
major impacts on conservation efforts and agriculture.”
Although smoke is a complex mixture of thousands of different
compounds, recent work at UWA and Perth’s Kings Park
laboratories was able to identify a single ‘smoke alarm’
component that snaps seeds out of dormancy.
UWA chemist Gavin Flematti, who discovered the active compound,
has since created similar chemicals that can stimulate
germination, and will also present his findings at the Mexico
conference.
To reflect the original source of such compounds, Dr Flematti
has named the family ‘karrikins’, from ‘karrik,’ the first
recorded word for smoke in the local Aboriginal Nyungar dialect.
“While the discovery of karrikins represented a major
breakthrough, helping us identify what seeds recognise in smoke,
we still didn’t know how they sensed it,” Dr Nelson said.
With so little known about the biochemistry and genetics of
native Australian plants, Dr Nelson turned his attention to the
‘laboratory rat’ of plant science, Arabidopsis thaliana, to
investigate the impact of karrikins on germination.
“Using Arabidopsis allows us to get so much more done in a short
period of time, and we can take advantage of the tremendous
amount of research already being done on germination worldwide,”
he said.
“Once we establish how a process works in Arabidopsis, we
typically find a remarkably similar system in other plant
species.”
An important first finding for Dr Nelson was that dormant
Arabidopsis seeds clearly respond to karrikins, even though fire
isn’t a normal component of their environment.
“The response to the ‘smoke alarm’ is more widespread than we
initially thought, and certainly impacts more than a few select
native species. This also suggests karrikins may be produced in
the environment other than in smoke,” Dr Nelson said.
He went on to demonstrate karrikin-enhanced germination for a
number of mutants with altered plant hormone levels. Then to get
a better look at the genetic changes underlying the germination
response, Dr Nelson used the latest technologies to determine
which of 23,000 Arabidopsis genes were switched on or off after
a karrikin treatment.
“For the first time, we have an idea of the molecular changes
that karrikin produces inside seeds. Using this information,
we’re starting to understand how a karrikin signal integrates
with other plant hormone pathways to wake a seed up from
dormancy,” he said.
Dr Tim Kaethner, Chief Operations Office at the ARC Centre of
Excellence in Plant Energy Biology, said the research of Dr
Nelson and his collaborators, presented for the first time in
Mexico, was likely to usher in a new wave of naturally occurring
plant growth-promoting substances of double significance.
“Not only will they help us understand more about the molecular
controls of that fundamental life-sustaining process of
germination, but may also be of economic benefit to farmers for
treatment of paddocks for weed control before crop seeding, as
well as in plant nurseries, the horticulture industry, land
management and in environmental rehabilitation,” Dr Kaethner
said.
BACKGROUND
ARC Centre of
Excellence in Plant Energy Biology
… targeting the discovery and characterisation of molecular
components and control mechanisms that drive energy metabolism
in plant cells.
The Australian Research Council (ARC) Centres of Excellence
scheme establishes research teams to focus on critical problems
through highly innovative research. The aims of the scheme are
to build national research capability and produce outcomes of
economic, social and cultural benefit to Australia.
The ARC Centre of Excellence in Plant Energy Biology focuses on
unlocking the secrets of the biological chemistry inside plant
energy organelles. We are an exciting new enterprise integrating
the intellectual power of seventy researchers at three
universities around Australia - The University of Western
Australia, The Australian National University and The University
of Sydney. For additional information please visit our web site
at
www.plantenergy.uwa.edu.au |
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