Hatch, Marshall Davidson (1932– )

Australian biochemist who described the mechanism by which tropical plants trap carbon dioxide in bundle sheath cells, the major sites of photosynthesis. He also published on many other areas of plant metabolism, including how plants break down starch and sugars to form ethanol and carbon dioxide.

During photosynthesis in plants, light energy is used to convert water and carbon dioxide to oxygen and energy-rich organic compounds (such as starch) in a series of enzymatic steps called the Calvin photosynthetic pathway, or C3 pathway. The rate limiting step of the Calvin pathway is a reaction catalysed by the enzyme rubisco. Since the activity of rubisco increases rapidly as the temperature rises, tropical plants might be expected to have a problem with excessively high rates of photorespiration.

In 1968, Hatch reported an alternative to the Calvin pathway, known as the C4 or Hatch–Slack–Kortschak pathway of enzymatic steps, for incorporating carbon dioxide into carbohydrates. The C4 pathway had evolved in tropical grasses and other plants experiencing climatic extremes to circumvent excessive photorespiration.

Hatch was born in Perth, Australia and studied at Sydney University and later in California. He worked for the the Colonial Sugar Refining Co. in Sydney 1961–70, before moving back to botanical research at the Commonwealth Scientific Industrial Research Organization (CSIRO) in Canberra, where he has been since 1970.