His early work established a rigorous foundation for yeast genetics. He established the Genetics Department at Seattle as a center of yeast research and played a key role in promoting yeast as a prime experimental system for molecular genetics of eukaryotes. He deserves much of the credit for the vitality of contemporary yeast genetics.
Herschel Roman accepted a faculty position at the UW in 1942 fully intending to continue the research on corn genetics he had begun as a graduate student. What he had not counted on, however, was the weather.
As anyone who has ever tried a bit of vegetable gardening west of the Cascade Mountains knows, corn can be a little tricky. "Knee-high by the Fourth of July" is the theory for corn, but in practice, a few damp, gray June days can wilt that hope.
"I became convinced that it was time to change organisms if I were to remain in Seattle," wrote Roman in a recollection of the early days of research on yeast genetics. He had tried growing corn outside; in greenhouses; he tried going to the California Insitute of Technology in Pasadena to grow it; and he tried raising it in Cle Elum, east of the Cascades where the UW had a field operation.
But by 1947, in a move that ultimately would be a boon to the field of genetics, Roman gave up altogether on corn and turned his attention to yeast. "His most important contribution scientifically was in characterizing the genetics of the budding yeast, Saccharomyces cerevisiae, which had been a misunderstood curiosity to that time but which Roman himself turned into an ideal organism in which to explore the nature of recombination, wherein chromosomes from either parent exchange genetic material," writes Breck Byers, chair of the UW genetics department. Roman's work revealed how recombination involves not only the trading of whole sets of genes between chromosomes (termed "crossing over") but also the transfer of information within individual genes (termed "gene conversion"). "These contributions stimulated wide-spread recognition that the molecular processes taking place in yeast are nearly identical to those required by the cells of all higher organisms, including man. This similarity, in conjunction with the fact that yeast is highly amenable to genetic analysis and study, has made yeast one of the key research organisms throughout all of biology," Byers notes.
Byers further points out that Roman's work provided the foundation on which many later applications by UW faculty were developed, including Leland Hartwell's work on the yeast cell cycle (see The Cell Cycle); Benjamin Hall's work to coax yeast to produce foreign proteins of interest (see A Triumph of Biotechnology: Genetically-Engineered Hepatitis Vaccine); and technologies developed by Maynard Olson that are fundamental to the Human Genome Project. Byers hails Roman's accomplishments as leading to "one of the most productive directions of biological science in the past 30 years."