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Interview: Light and life
18 May 2007
Are lawnmowers a thing of the past? Pill-Soon Song explains all to Celia Clarke.
|Pill-Soon Song is a professor of photobiology at the Cheju National University, Korea. He is Editor-in-Asia for Photochemical and Photobiological Sciences (PPS). His research interests are in the interactions between light and organisms, in particular the effect of light on plant development.|
What motivated you to study photobiology?
I've always been interested in looking at life and living processes from chemical and physical points of view. To some extent by coincidence and to some extent by design, I became interested in living processes associated with light. Light played a fundamental role in the origin of life and subsequently in the evolution of living systems. There are processes of living systems that are absolutely dependent on light, like photosynthesis in plants and vision in animals. So, I became interested in the photobiological aspects of living processes, which is a combination of biology and physics.
Which is the most likely outcome of artificial photosynthesis, a fix for increasing CO2 levels or a new energy source?
There are several ways to harness solar energy by directly fixing CO2 and reducing it to the level of carbohydrates - in other words mimicking or improving plant photosynthesis. Probably the most direct way is to increase the CO2 fixation efficiency of plants, for example, by genetic engineering. This is an important approach to harness solar energy more efficiently. But for more artificial harnessing of solar energy, for example for solar cells, the most common system is the photochemical splitting of water to generate hydrogen as a fuel source. Many laboratories around the world are working in this major research area.
How far are we from achieving anything that can compete with a fossil fuel power station?
What are you working on at the moment?
I am working on how plants respond to light by regulating their growth and development. Plants are not able to move around so they have to adapt to environmental situations. For example, if plants are in the shade they cannot photosynthesise efficiently and, since they cannot move into brighter daylight, they respond to the shade light at the molecular level. The shade light causes a set of genes to make the plants grow upwards in search of light and that's called the shade avoidance response. All plants have this response.
Plants have light-absorbing visual pigments, like our rhodopsin, called phytochromes. In bright daylight the major component of light is 660nm wavelength red light, and upon absorbing this light, one phytochrome form transforms into another, physiologically active form. This activates certain genes involved in growth and development and it can be switched off by absorbing longer wavelength, 730nm, shade light. So, you have an on-and-off switching system in plants that means they can dynamically respond to their light environment.
You have a project involving lawn grass. What is this about?
We are applying our understanding of the shade-avoidance mechanism to biotechnological and commercial uses. Lawn grass grows in a compact situation - this dense growth creates shadow on its neighbours and triggers the grass to grow vertically as fast as it can, to avoid the shade. So, you have to mow the lawn more often. Also, if lawn grass is kept in the shade it doesn't develop chlorophylls so it cannot photosynthesise. We are trying to make the plants tolerate and not avoid the shade. And by tolerance, I mean that the plants remain green and can absorb and use the shade light to regulate their growth so that they don't have to grow as tall.
And you do this by chemically and genetically modifying the plants' phytochromes. The phytochrome absorbs 660nm light, so it cannot effectively absorb the 730nm shade light - as far as the plant is concerned, when it is in the shade, it is in the dark. So we are changing the wavelength of absorption of the phytochrome toward the wavelength of shade light. Then, when you introduce a genetically engineered phytochrome gene into lawn grass, the grass in the shade sees the shade light more effectively and it grows slower. So you don't have to mow the lawn as often. It also means that you're using up less water because you're not having such rapid growth and, since a lot of water is good for fungal infections, you can minimise disease too.
What lies in the future for photobiology?
I think there will be two major avenues of research. One is the fundamental area - to understand how light affects living systems and processes. The other avenue is applied aspects - the lawn grass is a minor example, but a more important issue is the energy problem we are facing on the planet. One way to improve energy production by plants is to cut down on shade avoidance. You can shorten the stems of rice plants and corn, and this will result in more starch in the grains. Applied photobiology could lead to increased energy production from crop plants. There is also an area of extremely active research called photodynamic therapy: using light in combination with a light-absorbing, so-called photosensitiser, compound to treat cancer and skin diseases.
The Korean government declared 2006 the 'Year of Chemistry.' What are the aims of the program?
The Korean government is collaborating with the Korean Chemical Society to promote chemical science among young people. This is done through emphasising chemistry in the school curriculum and promoting a hands-on teaching approach. As a result, many of Korean students perform very well in the international chemistry Olympiad. In spite of all these efforts, like many other countries, the natural sciences, including chemistry, are not among the most popular subjects. This is why the government, chemical society and other institutions are trying to attract young students into sciences.
You have worked in both Korea and the US. What are the most striking differences you have found between academic life in the two countries?
In the US, research is funded by governmental, industrial and private agencies. In Korea most of the research is supported by governmental agencies. Another difference is that the research done in the US is by an individual grantee - you apply individually in most cases. But in Korea you apply for funding as a group of researchers with some common interest and the funding is divided.
There are pros and cons of both of these systems. In the US, graduate students and postdocs are very well supported financially. In Korea, a graduate student still has to worry about paying for tuition. The funding is much more competitive in the US; from the practical point of view of getting money to do research, the Korean situation is better.
In spite of that, I think the infrastructure is much better in the US, including the way the faculty, the graduate students and the postdocs are assisted by expert technical staff: secretaries, repair and maintenance staff and so on. Overall, Korea has to improve its research environment conditions.
PPS recently featured a United Nations Environmental Program report on interactions between ozone depletion and climate change. In your opinion, how much of a cause for concern is the depletion of the ozone layer?
Ozone is an extremely important factor in photobiology because skin cancer, for example, is affected by the amount of UV radiation in sunlight and that is determined by the depth of the ozone layer. The more information we can get and spread to the general readership, and public eventually, the better. One of the roles of photobiologists, photobiological societies and journals like PPS is to let people know about the importance of the ozone layer, how to prevent the depletion of the ozone layer and how to cope with the increased UV radiation from the sun.
And finally, if you weren't a scientist, would you do?
I'd probably be a medical doctor. I like the idea of an eye doctor - an ophthalmologist - which is to do with photobiology. Or a skin doctor - a dermatologist - it's also related to photobiology, skin photobiology.
Differential interactions of phytochrome A (Pr vs. Pfr) with monoclonal antibodies probed by a surface plasmon resonance technique
Chihoko Natori, Jeong-Il Kim, Seong Hee Bhoo, Yun-Jeong Han, Hiroko Hanzawa, Masaki Furuya and Pill-Soon Song, Photochem. Photobiol. Sci., 2007, 6, 83