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Biographical entry Letham, David Stuart (Stuart) (1926 - )

FAA, FRSNZ (Hon)

Born
8 September 1926
Ashburton, New Zealand
Occupation
Chemist and Biochemist

Summary

David Stuart (Stuart) Letham is Emeritus Professor and Visiting Fellow at the Research School of Biological Sciences, Australian National University in Canberra. Prior to joining the School's Department of Developmental Biology in 1970, Letham was at the New Zealand Department of Scientific and Industrial Research. There he made several pioneering discoveries in plant science: the development of a new method for separating cells from plant tissues, techniques to grow fruit tissue in artificial culture media and most significantly he improved the storage quality of apples by growing them with more and smaller cells than usual. Letham has received many awards and accolades for his work and is a Fellow of the Australian Academy of Science (FAA) and an Honorary Fellow of the Royal Society of New Zealand (FRSNZ Hon).

Details

After completing a PhD at the University of Birmingham, David Stuart (Stuart) Letham returned home and joined the Department of Scientific and Industrial Research in Auckland, New Zealand (1956). He remained in the Department until 1969 and during this time became internationally renowned for several pioneering discoveries. Letham had developed a method for separating cells from plant tissues by removing calcium from the cell walls - the key to much subsequent work on plant protoplasts. He was the first to grow fruit tissue in artificial culture media. His most significant discovery came in the course of an effort to improve the storage quality of apples by growing them with more and smaller cells than usual. He used his artificial culture system to detect a new category of plant growth stimulants. Finding that young corn (Zea mays) kernels were a richer source of the new compounds than apple fruitlets, he isolated and chemically characterised a substance he named zeatin, which was the first of the naturally-occurring cytokinin growth regulators to be isolated. Today there are more than thirty known with the majority of these having been purified and analysed by Stuart Letham and his colleagues, at the Research School of Biological Sciences, Australian National University.

Zeatin occurs in corn kernels at about 1 part in 100 million. To purify molecules that are present in such minute quantities Letham had to develop and apply the most rigorous and sensitive procedures of analytical chemistry. He pioneered methods of gas chromatography, mass spectrometry and high performance liquid chromatography in painstaking studies that not only identified many of the new regulators, but showed how they are formed, transported and broken down in plant tissues. All of this advanced chemistry was combined with studies of the biochemical and physiological properties of cytokinins, which are now known to control many aspects of plant development, including cell division, growth and senescence. In recent years Stuart Letham added the techniques of genetic engineering to his repertoire and engaged in a number of applied problems in collaboration with Calgene Pacific (now Florigene) while still continuing his fundamental research.
Source: edited from the biography supplied by Janet Elliot, Research Assistant, Plant Cell Biology, Research School of Biological Sciences

Events

1946
Education - Bachelor of Science (BSc) completed at Canterbury University College (University of New Zealand)
1948
Education - Master of Science (MSc) completed at Canterbury University College
1949 - 1950
Career position - Analytical Chemist with the New Zealand Department of Agriculture at Ruakura Animal Research Station in Hamilton
1950 - 1952
Career position - Biochemist with the New Zealand Department of Agriculture at Ruakura Animal Research Station
1955
Education - Doctor of Philosophy (PhD) completed at the University of Birmingham, UK
1956 - 1969
Career position - Scientist with the Department of Scientific and Industrial Research in Auckland, New Zealand
1964
Award - Research Medal received from the New Zealand Association of Scientists
1970 - 1986
Career position - Senior Fellow at the Research School of Biological Sciences at the Australian National University in Canberra
1983 -
Award - Fellow of the Australian Academy of Science (FAA)
1985 -
Award - Honorary Fellow of the Royal Society of New Zealand (FRSNZ Hon)
1986 - 1991
Career position - Professorial Fellow at the Research School of Biological Sciences
1988 - 1991
Career position - Head of Plant Cell Biology at the Research School of Biological Sciences
1991
Award - Medal for Excellence in Research received from the International Plant Growth Substance Association
1992 - 1998
Career position - Visiting Fellow at the Cooperative Research Centre for Plant Science at the Australian National University
1999 -
Career position - Emeritus Professor and Visiting Fellow at the Research School of Biological Sciences

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Annette Alafaci