A new chlorophyll – redefining photosynthesis: 2011 Science Minister’s Prize for Life Scientist of the Year

Min Chen

Among the single-celled cyanobacteria—formerly known as blue-green algae—which live in the ancient rock-like accumulations called stromatolites in Shark Bay, Western Australia, Associate Professor Min Chen of the University of Sydney last year found the first new form of chlorophyll in 67 years.

Chlorophyll is central to life on Earth. It is the key molecule in photosynthesis, the process by which plants harness sunlight. It provides our food, our fossil fuels and the oxygen we breathe. But this new variant, chlorophyll f, is particularly significant for our sustainable future because it harvests far red light, which is lower on the energy spectrum than visible light. So it broadens the range of light that can be used for photosynthesis, and opens the way to more efficient energy collection in solar cells and crop plants.

Even before the discovery of the new chlorophyll made her name widely known in scientific circles, Min Chen, still less than eight years out from her PhD, had become an acknowledged authority on photosynthesis. “Dr Chen is now the unquestioned world expert on the biology and biochemistry of photosynthetic cyanobacteria that utilise alternative pigments to chlorophyll a,” writes Professor Robert Blankenship of Washington University in St Louis, Missouri.

For her contribution to our knowledge of chlorophyll and cyanobacteria, Associate Professor Min Chen receives the Science Minister’s Prize for Life Scientist of the Year.

As the daughter of a professor at China’s naval academy in Dalian in the country’s northeast, Min Chen was steeped in science and academia from birth. She trained in plant physiology at the North-East Normal University in Changchun where she first began research involving photosynthesis.

“For my masters, I studied soybeans. When you study plants, photosynthesis is the most important reaction. We were comparing levels of chlorophyll a and chlorophyll b and relating them to the biomass and yield of the soybean.”

After nearly four years in Germany working on plant tissue regeneration, Min Chen came to Australia in 1998 with her husband, a chemist, who had been appointed to the University of Sydney. To keep her hand in as a plant physiologist, she worked for nearly two years as an honorary assistant in the laboratory of Professor Tony Larkum at the University of Sydney, where the major interests included chlorophyll and photosynthesis. Finally, money was found for her to study for her doctorate—and she has never looked back.

She worked on chlorophyll d, a form of chlorophyll which harvests light at the red end of the spectrum. Discovered in 1943, it had been considered as something of an oddity, until in 1996 a Japanese research team found it was the predominant form of chlorophyll in a cyanobacterium species, Acaryochloris marina, which lives in low light. Min Chen wanted to know all about it and how it worked.

By the time she had finished her PhD she had published seven papers in refereed journals and had made a significant contribution to understanding how chlorophyll harvests light. The desire she had already shown to maintain and diversify her skills became the hallmark of her work. The papers to which she has put her name, which now amount to more than 50, cover a range of disciplines, from molecular biology and biochemistry to taxonomy and evolutionary biology.

“Dr Chen’s outstanding publication record of the last several years is clear evidence that she has excellent lab skills, amazing persistence and the ability to juggle many things simultaneously and bring them all to conclusion successfully,” says Professor Blankenship.

Even before completing her PhD, she was highly sought around the world as a postdoctoral fellow. But she was also recognised in Australia with an Australian Research Council postdoctoral fellowship. This enabled her to establish her own laboratory in Australia as an independent researcher.

Acaryochloris marina was found in a rather strange environment—in coral reefs on the underside of the strange stalked creatures known as ascidians or sea squirts. Min Chen now wanted to know how widespread A. marina was, and whether there were cyanobacteria using chlorophyll d in other environments. So she began looking—and the search took her to the stromatolites of Shark Bay.

“Finding the new chlorophyll was totally unexpected—it was one of those serendipitous moments of scientific discovery. I was actually looking for chlorophyll d, which we knew could be found in cyanobacteria living in low light conditions. I thought that stromatolites would be a good place to look, since the bacteria in the middle of the structures don’t get as much light as those on the edge.”

To Min Chen, as a scientist, the finding of chlorophyll f is significant because of the understanding of the evolution and mechanism of photosynthesis it can provide. “Cyanobacteria were the first organisms to produce oxygen, through photosynthesis. They transformed the early Earth and changed the course of evolution.”

To others, chlorophyll f represents new opportunities. “The discovery of chlorophyll f is an extremely important development that has rewritten the textbooks and promises to have important applications in agricultural and bioenergy systems,” says Blankenship.

Qualifications

2003	PhD (Plant Molecular Biology), University of Sydney
1987	Master of Science, North-East Normal University, Changchun, China
1984	Bachelor of Science, North-East Normal University, Changchun, China

External links

View a profile of Min Chen at http://sydney.edu.au/science/biology/about_us/academic_staff/chen_min/