Jack Dainty was an outstanding plant biophysicist who transformed our understanding of the transport of ions and water across plant membranes.

He was born in 1919 and grew up in the coalmining area of southern Yorkshire amid widespread unemployment. This experience left a profound impression on him and he remained a lifelong socialist. He won scholarships first to Mexborough Secondary School and then to Cambridge. Initially he studied mathematics but switched to physics and graduated with a first in 1940. Shortly afterwards he joined a team in Cambridge studying nuclear fission. He was appointed head of the cyclotron team and taught numerous physics courses, acquiring an expertise in physics that served him well when he later began to tackle biological problems.

For his contributions to nuclear physics he was awarded the Stokes Medal by the University of Cambridge in 1945. In 1946 he moved to the Canadian Atomic Energy Laboratories at Chalk River, Ontario. He returned to the UK in 1949 and joined the faculty of the Department of Natural Philosophy at the University of Edinburgh, where he built up a research group in nuclear physics. In the early 1950s he taught elementary physics to medical students, but the university promised him a department of biophysics and he switched into biology, as he said, “almost by accident”. He joined forces with a colleague to study sodium exchange across the nerve membranes of cats, as he felt that the overall aspects of transport could be placed in the physics domain. However, he quickly realised that membrane transport in plant cells, which is different from that in animal cells, had received little attention from a biophysical perspective and so embarked on a life-long study of this subject.

In a pioneer study he and a graduate student, Enid MacRobbie (later a Professor and FRS) used radioactive tracers to study ion fluxes in a large single-celled alga. The findings were novel and the study received wide acclaim.

Ion and water transport were also being studied in Australia, and Dainty spent six months there working with Alex Hope on water permeability and ion-exchange properties of the cell wall of another single-celled algal species. They showed that water exchange between cells and the external environment was controlled by diffusion in unstirred layers of water external to the plant cell. This important finding established the need to take into account unstirred layers in biological transport processes. Further studies indicated that mineral ions within cell walls can be easily lost to the external solution. These findings reflected the application of biophysical principles that transformed this research field.

Perhaps one of Dainty’s greatest contributions was introducing plant scientists to the value of a biophysical approach to plant membrane transport. In the early 1960s he published two seminal reviews on ion and water transport. The latter, in particular, was not so much a review as a theoretical treatment of plant-water relations and the need to adopt a more thermodynamic approach to characterise the driving forces governing water (and ion) movement across plant cell membranes. The reviews had an immediate impact but it took longer for the approach to be accepted by a wider readership as it demands an understanding of thermodynamics.

Although not a strong experimentalist himself, he attracted able young scientists and colleagues to Edinburgh with whom he interacted successfully in designing experiments. He was influenced by the research findings of the animal physiologists which emphasised the passive movement of ions and as a result he did not embrace the hypothesis that ion uptake in plant roots occurs via ion carriers in cell membranes that can be described by enzyme kinetics.

In 1963 he moved to the new University of East Anglia as the founding professor in biophysics in the School of Biological Sciences. As at Edinburgh he developed successful post-graduate courses in biophysics. Scientists came from around the world and it was an exciting period with investigators pursuing their individual studies. In 1969 he moved first to the Laboratory of Nuclear Medicine and Radiation Biology and then to the Department of Botany at UCLA and finally to the University of Toronto in the chair of the Department of Botany in 1972. He was also associate editor of Plant Physiology.

Dainty was an outstanding chair and he helped to make the department one of the strongest in North America. Much of his success can be attributed to his low-key approach and his ability to listen to people, coupled with a strong sense of fair play.

Upon stepping down as chair, he was honoured with the appointment to university professor. His other honours included fellowship of the Royal Societies of Canada and Edinburgh, an associé étranger of L’Académie des Sciences de l’ Institut de France, and an accademico of the Accademia Nazionale dei Lincei, Rome. He was awarded the Gold Medal of the Canadian Society of Plant Physiologists and was a corresponding member of both the American Society of Plant Physiologists and the Botanical Society of America.

In 1941 Dainty married Mary Elbeck. They had three sons and a daughter who is deceased. They separated and he married Trish Shea in 1968 with whom he had two sons. They also separated but remained close friends. She and his sons survive him.

Professor Jack Dainty, plant biophysicist, was born on May 7, 1919. He died on May 29, 2009, aged 90