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My name's Harvey Millar, I'm a Professor here at the ARC Centre of Excellence in Plant Energy
Biology at the University of Western Australia. We're interested in Energy Biology, now that
may seem a strange concept to you but in fact it's the biggest biochemical reaction that
runs our world. It basically produces our food, our fuel, the feed for our animals and
the fabrication materials that we use. But in the future we'll have an increasing demand
for all of these things with growing world population and yet at the same time, we have
increasing environmental concerns which mean that it's more and more difficult for our
systems to provide these things. So understanding Energy Biology and the efficiency of that
process is really critical for the future.
We're not doing this alone; we're actually involved in collaborations around the world.
So we have collaborations at the Umeå Plant Science Centre in Sweden, at the Salk Institute in San Diego
and Max Planck Institute for Molecular Plant Physiology outside of Berlin. As we work together
as a team to try to build our understanding of the energy system in plants and how that
can be improved for the future.
We think about the lights in our houses and how efficient they might be and how much we
might be paying for our electricity but have you ever thought about how efficient a plant
actually is? We look at plants and we see that they use light from the air, they use
nutrients from the soil and they take gases from the air. And so they seem pretty efficient
but surprisingly a plant's only about one per cent efficient in the way that it can
take light and convert that energy into chemical energy inside the plant. And of that one per
cent, only about ten per cent is actually able to be taken by the plant and converted
into products that we want; into food and feed and fabrication materials. That inherent
inefficiency of plants arises from the fact that plants gain carbon through photosynthesis
but they lose a lot of that carbon through the process of respiration. You see plants
have to respire just like we do in terms of converting that sugar and that food into energy
which allows them to grow and develop.
Plants respond not just to the quantity of light but also the quality. By changing the
wave length of light that plants see we're able to alter the way in which photosynthesis
and respiration interact and their rates. We can do that by using LED's that alter the
quality of light so that in a growth room we can have a red light at dusk, we can have
a shaded environment, we can have a bright sunny day, all by altering the light quality
using a series of different LED's of different colours. We can also use this technology along
with photography to do time lapse images of plants and we can use this information to
look at the rate at which plants are growing and understand variations between plants in
their rate of accumulation of biomass over time.
When temperatures rise photosynthesis starts to plateau but respiration actually increases
and as temperatures of plants drop we find that photosynthesis decreases but respiration
stays higher as the cells try to maintain enough energy for the plant to actually live
and survive. If we treat these plants with salt which is mimicking really a saline environment
what we'll see is that photosynthesis will start to drop but respiration will actually
climb as the plant tries to make enough energy to cope with keeping the salt out. These changes
that are happening in photosynthesis and respiration, this balancing act that's happening, is really
the efficiency of plants but this balancing isn't really just theoretically interesting,
it's actually fundamental, to having sustainable crops for the future as we live in a world
where we have more people but no more arable land.
This respiration process which is affecting this efficiency occurs in mitochondria, which
are small structures in cells in plants but also in ourselves. We can purify these mitochondria
structures and actually study all the different proteins that make them up. And so you can
see here that hundreds of different proteins, from hundreds of different genes in plants
which are actually involved in this respiratory process in mitochondria. And we can analyse
these in mutants and look for small changes that are happening in the mitochondria which
affect this respiration process.
To find out what the proteins are that are changing under those different conditions
we need to use a technique that will link the proteins to the genes that actually encode
them. We do that using mass spectrometry. What you can hear is actually vacuum pumps
pulling down the atmosphere in these machines so that we can move peptides round the gas
phase. Here we have a peptide a hundred million times the size the peptides are that are actually
in this machine. And what we're doing is measuring complex products like this made from proteins
right down to a hundredth of the mass of one of these white protons that we can actually
see in this structure.
How these machines work is by throwing these peptides in the gas phase up these flight
tubes and measuring the time that it takes them to come down to the bottom again. In
that way we can build the information about the proteins that are actually found in the
samples, link them to the genes and build databases of how plants are responding to
environmental changes.
We're also interested in the way in which plants actually respire not just what's inside
them. To do that we actually need to measure respiration rate or the oxygen consumption rate inside
leaves. Leaves aren't all the same so if you look across a plant you will find that different
leaves will be respiring at different rates. What we're doing here is using technology
that's been developed to look at cancer cell respiration to look at plants and actually
taking 2mm circles so that we can look at the respiration rate of each individual leaf
in a plant.
Because respiration is such a fundamental component of how plants actually operate we
can look at respiration and study it in a whole variety of different plants and compare
the findings. Here what we're doing is actually looking at wheat varieties that vary in their
tolerance to salt in the environment and in the soil. What we find is that plants can
be tolerant or they can be intolerant to that salt. Respiration's also changing and those
changes in respiration are important in understanding the efficiency of different wheat varieties
in response to salt. When we think about the designer plants that we're going to be growing
in the future and using as food they're less likely to have a gene from a fish or a spider
or a frog in there. They're much more likely to be small variations in what wheat is naturally
doing to alter its tolerance to salt.
Bringing all the elements of Energy Biology together to make improvements for the future
is a long term venture as we move towards 2020 and then on to 2050 as the world population
grows it will be these international collaborations between researchers working together to produce
outcomes in field crops that are needed in different countries which will be vital for
the future. The Plant Biologists have a key role in this right now to actually find the
genes which are critical for this process so that we can find the best ways and the
best solutions for improving the crops of tomorrow.