Anecdotal , Historical and Critical Commentaries on Genetics Edited by James F . Crow and William F . Dove Marcus Rhoades , Preferential Segregation and Meiotic Drive

LONG before microarray biologists coined and proone familiar with the usual course of events, the sight moted the term “discovery science,” maize genetiof this progression is indeed fascinating. cists were avid practitioners of this mode of investigaRhoades was born in Missouri and raised in Kansas tion. In fact, one might say that for a number of years, (Dempsey 1973, 1983, 1994). Eventually he found his the field of maize genetics basically operated as discovway to the University of Michigan, where he encounery science. Many have speculated about why maize retered E. G. Anderson “of attached-X fame” (Rhoades’s mains a model organism for genetic analysis, given its own phrase). Anderson had just demonstrated, using long life cycle relative to other species. It has many attached-X females of Drosophila, that crossing over virtues, sometimes little understood or appreciated by occurred at the four-strand stage of meiosis. Rhoades’s outsiders, but the maize geneticist’s style of science deintroduction to genetics was a seminar on this topic convoted to discovery and an unusually strong commitment ducted by Anderson (Dempsey 1994). Rhoades was reto cooperation probably contributes to this trend. One portedly befuddled by this topic, but determined to underof the great practitioners of this style of science was stand it. Under Anderson’s tutelage, Rhoades went on Marcus Rhoades (Figure 1), who often advised beginto receive a master’s degree in genetics from Michigan, ning graduate students: “Just get in the lab and start to at which time he was encouraged to enter the Ph.D. work; you can’t help but find something.” “What are program at Cornell to work with R. A. Emerson. Emerthe facts?” was his common refrain to model building son had been Anderson’s own Ph.D. advisor. It was at and theorizing. Along with his penchant for discovery Cornell that the stellar group of Rhoades, George Beawas a dogged experimentalist attack to explore the padle, Charles Burnham, Barbara McClintock, and Emerrameters and dimensions of a new finding. son coalesced to elucidate many features of maize genetRhoades discovered the first case of cytoplasmic male ics and cytogenetics in general. A photo of this group, sterility in maize; the independence of the plastid from together with Beadle’s dog, taken during pollination nuclear control by the action of the iojap mutation; the season has been widely reprinted (e.g., Sheridan 1982; Dotted “mutator” system that was later found to be a Dempsey 1983; Keller 1983), and many have commented transposable element (see Fedoroff 1998); many feaupon the collection of talent that was present at Cornell tures of chromosomal behavior; the “duplicate” nature at that time (see also Nelson 1993). Rhoades showed of the maize genome; effects of supernumerary chromothis picture to his cytogenetics class at Indiana University somes on the normal set; and preferential segregation in 1974 and remarked in an uncharacteristic lapse of resulting from neocentromere formation caused by abmodesty, but with characteristic wit, “Even the dog was normal chromosome 10 (Dempsey 1973, 1983, 1994; smart!” Peterson and Peterson 1973). This last topic mainIt was at Cornell that Rhoades began an enduring tained Rhoades’s interest until the end of his career. It friendship with Barbara McClintock (Rhoades 1984). is, in fact, a rather astounding phenomenon: a variant He was a strong advocate of her work and an admirer of chromosome 10 will cause blocks of heterochromatin of her abilities both in terms of cytological technique on all chromosomes to proceed to the poles of meiosis and interpretation. Rhoades (1984) recalled his role in ahead of the normal centromeres (Figure 2). For anygetting her to apply her cytological skills to the research problems of the Cornell maize genetics group (see Kass and Bonneuil 2003 for a detailed account of all the 1Corresponding author: Division of Biological Sciences, 117 Tucker factors involved). His course material covered all of her Hall, University of Missouri, Columbia, MO 65211. E-mail: [email protected] studies, and the laboratory instruction included advice