November 10, 1932–February 12, 2007
BY KENT J. BRADFORD
SHANG FA YANG WILL BE REMEMBERED as the plant biochemist who elucidated the pathway for the biological synthesis of ethylene, a plant growth-regulating hormone. Ethylene, a simple compound containing two carbon and four hydrogen atoms, was known already in the early 20th century to elicit abnormal growth in plants and to hasten the ripening of fruits. This remained somewhat a curiosity associated with leaking gas mains until it was shown in the 1930s that plants produce ethylene and that it is broadly involved in regulating plant growth and development, including seed germination, root and shoot growth, responses to environmental stresses, flowering, fruit ripening, and senescence or death of plant tissues and organs. The fact that ethylene is a gaseous compound made it unique among plant hormones, and it was of considerable interest to understand the mechanism and biochemical pathways by which plants produced the compound.
At the time Yang entered the field there was some evidence that the amino acid methionine could be a precursor for ethylene production, and various in vitro systems were being explored to convert this and other potential precursors into ethylene. Yang contributed significantly to these studies, using his knowledge of chemistry to explore different reaction