United Kingdom
March 4, 2008
A team of
Biotechnology and Biological
Sciences Research Council (BBSRC) funded scientists at the
University of Essex has discovered a new mechanism that slows
the process of carbon dioxide fixation in plants.
The research, published today in the
Proceedings of the National
Academy of Sciences, increases our understanding of this
process, which may ultimately lead to crop improvement and
‘fourth generation’ biofuels. The mechanism, which helps to
regulate the way in which plants absorb carbon dioxide (CO2)
from the atmosphere and turn it into sugars, acts by putting the
brakes on sugar production when there is not enough energy from
sunlight available. As sunlight increases, the brakes are
rapidly released and carbon dioxide fixation speeds away.
Plants are dependent on sunlight to capture carbon dioxide,
which is turned into important sugars via a process called the
Calvin cycle. As a result, as the amount of sunlight varies
during the day (e.g. through cloud cover or shading from other
plants), they must also be able to vary the speed at which they
capture carbon dioxide from the atmosphere. This ensures that
when there is a lot of sunlight, it is taken full advantage of
but that when sunlight drops, so does CO2 uptake. This ability
to maximise energy use is important for plants and prevents the
loss of important metabolic resources. Because they essentially
stay in one place, plants must have many unique abilities to
adapt to their environment as it changes around them.
The question is how does this variable speed control actually
work" The BBSRC-funded research shows for the first time how the
Calvin cycle can be regulated in response to a changing light
environment via a molecular mechanism. There is a special
relationship between two enzymes that are involved in the Calvin
cycle – phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate
dehydrogenase (GAPDH). When light levels decrease, the two
enzymes tend to stick together and therefore cannot function,
thus slowing the Calvin cycle. The darker it is, the more
PRK-GAPDH partnerships are formed and the slower the Calvin
cycle becomes. In the light, they break apart rapidly and the
Calvin cycle is allowed to speed up.
This fundamental research has revealed a novel mechanism and
provides a better understanding of the regulation of CO2
fixation in plants. This work will underpin strategies to
increase the amount of carbon dioxide absorbed by plants thereby
increasing yield for food and biofuel production, and may
ultimately feed into the development of ‘fourth generation’
biofuels.
Research Leader, Professor Christine Raines of the University of
Essex, said: “Although this research focuses on the fundamental
biological processes that plants use, ultimately, if we can
understand these processes, we can use the knowledge to develop
and improve food and biofuel crops.”
Dr Tom Howard, who contributed to the research, said: “Plants
have evolved a fascinating way to cope with variations in their
local environments. Unlike animals, they cannot move on to look
for new food sources. This research helps to unlock one way that
plants deal with the ultimate variable – the amount of sunshine
they receive.”
Professor Nigel Brown, BBSRC Director of Science and Technology
said: “With a growing world population and increasing demands
for energy we need to consider new ways to improve food and fuel
production. Sophisticated basic research in areas which have
been studied for many decades, such as this work funded by
BBSRC, furthers our understanding of natural processes that have
the potential to be harnessed to meet future challenges.”
The research is published this week 3-7 March 2008 in the
Biotechnology and Biological
Sciences Research Council of the USA as a PNAS Early
Edition.
Thioredoxin-mediated reversible dissociation of a stromal
multiprotein complex in response to changes in light
availability
Thomas P. Howard, Metodi Metodiev, Julie C. Lloyd, and
Christine A. Raines.
http://www.pnas.org/cgi/doi/10.1073/pnas.0710518105
The Biotechnology and Biological Sciences Research Council
(BBSRC) is the UK funding agency for research in the life
sciences. Sponsored by Government, BBSRC annually invests around
£380 million in a wide range of research that makes a
significant contribution to the quality of life for UK citizens
and supports a number of important industrial stakeholders
including the agriculture, food, chemical, healthcare and
pharmaceutical sectors. |
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