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Thomas K. Hodges
Professor of Plant Physiology
The recipient of the Herbert Newby McCoy Award for 1989 is Thomas K. Hodges, Joseph C. Arthur Distinguished Professor of Plant Physiology. Professor Hodges received a B.S. in Agronomy from Purdue University in 1958 and a Ph.D. in plant physiology from the University of California at Davis in 1962. After receiving that degree he worked as a Research Associate in Agronomy at the University of Illinois before joining the Horticulture faculty at the University of Illinois in 1963. In 1971, Professor Hodges came to Purdue as a Professor of Botany and Plant Pathology. He served as head of the department from 1977 to 1982. He was named the Joseph C. Arthur Distinguished Professor of Plant Physiology in 1989. Professor Hodges has received many awards for his research including the Charles Albert Shull Award from the American Society of Plant Physiologists.
Crop plants have been improved systematically through plant breeding for nearly a century, and the remarkable increases in yield have been dubbed the green revolution in agriculture. We are now in the beginning stages of a gene revolution in plant biology that will extend conventional plant breeding, and it is anticipated that these new genetic technologies will provide the required boost in food production needed to feed a growing world population. The seminar will discuss the current status of genetic engineering of plants with special emphasis on transformation and regeneration of rice, maize, and other plants from single protoplasts (cells that have had the outer cell wall removed). Progress and problems in identifying genes of importance, the methods for insertion of genes into the DNA of the host plant cell, and in regrowth of the plant following insertion of the gene into an individual protoplast will be presented.
Professor Hodges' research in the last five years has concentrated on three problem areas: ion transport into plant cells, regenerating whole corn plants from naked (wall-less) cells, and regenerating rice plants from single cells. The first area is concerned with a better understanding of basic processes in plant nutrition. The other two are part of the world-wide effort in biotechnology to genetically engineer plants. Professor Hodges gained prominence in the 1970's for his landmark studies on plant plasma membranes and the biochemical apparatus responsible for moving ions across the membrane from the external environment to the cell's interior. He was the first to develop procedures for purifying plant plasma membranes; and he showed that an enzyme, ATPase, was involved in transporting ions across the membrane. In 1982, Hodges embarked on a new line of research devoted to developing the technology necessary for transforming the genetic character of plants. He focused on the major staple crops of the world that had been recalcitrant in adapting to emerging biotechnology. Regeneration of whole, reproductive plants from single naked cells called protoplasts was the goal because protoplasts are capable of receiving new genetic information. Regeneration of the cereals (corn, rice, wheat, barley) into whole fertile plants was an important undertaking because this was the major obstacle to the genetic engineering of these plants. He built a new program in plant cell and tissue culture with initial efforts focusing on corn. The overall approach was a systematic evaluation of the conditions and procedures required for regenerating plants. At this time there had been little success in regenerating corn from even large pieces of tissue. Hodges began with large pieces of somatic (body) tissue and then proceeded to smaller tissue pieces until single cells, and then protoplasts, were being investigated. Hodges recognized that the genotype as well as the nutrient environment were critical variables in determining whether or not the cells would grow. Only a few genotypes were capable of regeneration, and this led to the discovery that when a regenerable inbred plant was crossed with a recalcitrant inbred, the resulting hybrid would regenerate whole plants from single cells. This in turn led to the discovery that only two or three genes controlled somatic embryogenesis and plant regeneration. Hodges and his colleagues report the efficient transformation of corn protoplasts with two bacterial genes, simultaneously one gene makes cells resistant to an antibiotic, the other controls synthesis of a protein that is easy to measure. Thus, it is now possible to readily produce transgenic maize callus. Because of his tremendous success with the corn regeneration project, the Rockefeller Foundation asked Hodges in 1985 to develop a project on regeneration of indica rice, another major crop in the world. As with corn, indica rice regeneration was found to be under genetic control. During 1988, Hodges' group succeeded in regenerating indica rice plants from protoplasts. This is especially important because there is a great deal of interest in genetically engineering indica rice since the indica varieties are used in most of the developing countries of the world. Thus, with the development of the techniques for regenerating these rice cells, genetic transformation of rice plants is now possible. Throughout his career Professor Hodges has shown the ability to select important research problems and pursue them with systematic and innovative vigor. He is one of the best known and most respected plant physiologists in the country. Through his research he has made his mark not only in the advancement of basic plant physiology but now in the adaptation of plant biotechnology that will lead to improved crop plants for a hungry world. It is for his recent breakthrough in this universally respected research that Purdue University awarded Professor Hodges the Herbert Newby McCoy Award in 1989.