Marcus M. Rhoades, 1903-1991

The death of Dr. Marcus M. Rhoades on December 30, 1991 ended a long career devoted to the observation, study, and genetic manipulation of the maize plant. Dr. Rhoades held a unique place in the community of maize researchers. His associations with maize workers, spanning over six decades, left their mark on hundreds of individuals in all parts of the world. He will be mourned not only by his own students and close colleagues, but also by younger corn workers who treasure a few brief encounters with him and by good friends in universities across the nation whose visits to his laboratory were occasions for stimulating conversation and exchange of information.

Dr. Rhoades played an important role in the founding of the Maize Genetics Cooperation. The now legendary "cornfab" in R. A. Emerson's hotel room during the 1928 meeting of the Genetics Society of America, when the need for cooperative efforts became apparent, has been described in Rhoades's article on "The Early Years of Maize Genetics". Three and a half years later, the Maize Genetics Cooperation was formally organized; Dr. Rhoades was designated custodian of genetic stocks and also served in a secretarial capacity in the reports to corn workers that constitute the first issues of the Maize Genetics Cooperation News Letter. The tremendous excitement and creativity of that time when new discoveries were rapidly being made and the stimulus of daily interaction with fellow maize researchers such as McClintock, Beadle, Emerson, Sprague, and Burnham made his experience as a graduate student and postdoctoral experimentalist at Cornell a high point in Dr. Rhoades's life; he referred to that period as the "Golden Age of Corn Genetics". Many years later, Dr. Rhoades again became intimately involved with the Maize Genetics Cooperation when he supervised the transfer of the genetic stock collection from Ithaca to Urbana. At the same time, he took responsibility for the preparation of the annual News Letter; from 1956 to 1974, the News Letters were assembled, edited, and distributed from Urbana and, when he joined the Botany Department at Indiana University, from Bloomington. Dr. Rhoades was rightfully proud to be a member of an elite group of scientists who unselfishly shared unpublished information, exchanged stocks, and revealed new techniques in order to advance the knowledge of maize genetics.

Marcus Rhoades will be remembered in the annals of genetics as one of the giants who developed and shaped the fields of maize genetics and cytogenetics. He had the discernment to choose significant problems in his research; the continued interest in certain areas uncovered by his pioneering studies is a tribute to his perception and the keenness of his observation. The highly productive period at Cornell was followed by five years at Ames and later at Washington as a USDA geneticist. His first academic appointment was at the Associate Professor level at Columbia University. Eight years later, he transferred his laboratory and corn stocks to the University of Illinois at Urbana and, in 1958, he accepted an offer from Indiana University, where he served as Chairman of the Botany Department for ten years.

In 1981, at the age of 78, Dr. Rhoades was awarded the Thomas Hunt Morgan Medal of the Genetics Society of America in recognition of a lifetime's contribution to genetics. His first scientific paper appeared in 1931 and this News Letter carries a report of his last research efforts. Especially notable among his contributions is the study of the Dotted gene, sometimes regarded as a precursor of the work on transposable controlling elements. The induction of mutations in a by the Dt gene was thoroughly investigated with the genetic techniques available at the time. It was a remarkable system that attracted considerable attention and Dr. Rhoades often referred to the Dotted study as one of his most important contributions. Many years later, after the discovery of the Ac-Ds mutable system by McClintock, Earle Doerschug, a student of Rhoades, showed that Dt, like Ac, has the ability to transpose and molecular studies by Nancy Shepherd identified a Ds-like element inserted in the A locus. Work on Dt has continued with a developmental study by R. K. Dawe and Michael Freeling.

Another area of interest was non-Mendelian genetics. Rhoades's Ph.D. thesis on cytoplasmic inheritance of male sterility described the first instance in plants where a phenotype other than chlorophyll variegation was determined by cytoplasmic factors. This was followed by a study of plastid mutation by the iojap gene showing that constituents of the cytoplasm could be permanently modified by a nuclear gene. The publications that resulted are frequently cited in textbooks and corn workers such as Susan Gabay-Laughnan, John Laughnan, and Virginia Walbot, have continued to explore this aspect of maize genetics. A life-long study of abnormal chromosome 10 and the associated phenomena of preferential segregation and neo-centromere formation began during his years at Columbia. This example of "meiotic drive" had an observable cytological basis unlike some similar cases in Drosophila. In later years, Rhoades made use of a series of terminal deficiencies to elucidate the peculiar structural organization of the abnormal chromosome 10.

Dr. Rhoades had an abiding interest in chromosome mechanics and the influence of heterochromatic elements of the maize genome on such fundamental processes as recombination, meiotic segregation, and behavior of the chromosomes in the microspore divisions. The elegant study of the high-loss phenomenon showed how interaction of B chromosomes and knobs could cause breakage and loss of chromatin during gametogenesis. All of his research studies were pursued with characteristic energy, persistence, and attention to detail. His scientific papers are models of clarity and demonstrate his masterful command of the English language. Rhoades was also an articulate and lucid lecturer; hundreds of graduate students in botany, zoology, microbiology and agronomy will attest to the relevancy and usefulness of his cytogenetics course in their later careers. Drew Schwartz, one of the first of his 26 Ph.D. students, has written: "He is remembered by his students for his friendly informality, his patient tutoring, his ready wit as well as the thoroughness and dedication with which he presented his lecture material."

As one of the leaders in the field of Genetics, Marcus Rhoades won wide recognition from scientists throughout the world. he was invited to the University of Sao Paulo, to North Carolina State College, to Cornell University, and to the Australian National University at Canberra as Visiting Professor. He was elected to the National Academy of Sciences, the American Philosophical Society and the American Academy of Arts and Sciences. In addition to the T. H. Morgan Award of the Genetics Society of America, he received a Certificate of Merit Award for outstanding contribution to American botany from the Botanical Society of America. He was made a foreign fellow of the Royal Danish Academy of Science and Letters in 1977 and, in 1982, he received an honorary Sc.D. degree from Indiana University. On his 70th and his 80th birthdays, Dr. Rhoades was honored by festschrift volumes containing publications by his students and colleagues. Dr. Rhoades served on innumerable committees, panels, and editorial boards, but he regarded his 12 years participation as a member of the Selection Committee of the Guggenheim Foundation as the most rewarding and enjoyable of these experiences.

Marcus Rhoades's modest demeanor, his enthusiasm for sports, and his easy commerce with people from all walks of life endeared him to many. It is rare to find in one individual a sense of humanity and a common touch combined with a towering intellect and an unflagging dedication to research. Dr. Rhoades possessed these qualities in plentiful measure. Despite several severe setbacks in his health, Dr. Rhoades remained active in his laboratory until his last days. He continued to make pollinations, both in the winter greenhouse and in the cornfield north of Bloomington. He accepted the depredations of old age with grace, dignity, and a truly remarkable fortitude. Throughout his life, he expressed a strong appreciation and admiration of the corn plant--as a research object, as a nutritious food, and as a delightful source of beverage. He also had a deep spiritual affinity for the plant; at his request, his ashes will be scattered in the cornfield. The words written by Dr. Rhoades in a biographical memoir for L. J. Stadler apply equally well to his own passing. "The science of genetics lost one of its most distinguished men. According to his wishes . . . no funeral services were held. Unobtrusively and quietly he passed from this world of living men. But time can never erase from the minds of his students, friends and colleagues their memories of a wise and great man."

Ellen Dempsey

Marcus Rhoades Memorial Fund
One of the world's most distinguished maize geneticists, Marcus Rhoades, passed away on December 30, 1991. A fund in Marcus' memory has been set up at Indiana University. Disbursements from this fund will be used to provide money for graduate students at Indiana who may need it for any of a variety of reasons for which grant funds are not available. Anyone wishing to make a donation in memory of Marcus should send me a check made out to the I.U. Foundation - Marcus Rhoades Memorial Fund.
Tom Blumenthal, Chairman
Department of Biolgoy
Indiana University
Bloomington, IN 47405

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