Simon Chan is a 2001 Plant Science Program HHMI-GBMF Investigator.

Simon Chan

Syncopation, shifting moods, surprising juxtapositions of high and low notes—the music of jazz saxophonist Sonny Rollins was one of Simon Chan’s earliest inspirations. As a teenager in Auckland, New Zealand, Chan also played saxophone, and he dreamed of becoming a professional musician. But toward the end of high school, he realized he would enjoy music more as a hobby than as a career. He switched to science and started on a course that would take as many twists and turns as a Rollins riff.

Chan and his collaborators recently discovered ways to dramatically speed up the breeding of plants for desirable traits, but he never expected to discover anything so immediately applicable to agriculture. In fact, he didn't set out to study plants at all. His Ph.D. from the University of California, San Francisco, is in cell biology. It wasn't until his postdoctoral fellowship with HHMI investigator Steven Jacobsen at the University of California, Los Angeles, that he switched to plant biology, focusing on the mustard plant Arabidopsis thaliana, a common laboratory species.

"My postdoc research was in gene silencing, a mechanism by which repeated sequences … are suppressed so that they don't harm the genome," Chan says. "When I started in 2002, it was clear that plants—and Arabidopsis thaliana in particular—were great organisms for working out the details of the process" because the switches that turn genes off are inherited similarly in plants and in animals.

Since joining the faculty at the University of California, Davis, in 2006, he has used plants to understand a different aspect of chromosome biology: how chromosomes are inherited during cell division. This fundamental work set the stage for the findings related to crop plants.

It began with Chan's interest in the centromere, the cinched-waist portion of a chromosome, whose job is to direct chromosome movement during cell division. Centromeres make sure that once the chromosomes have been duplicated, one copy is delivered to each daughter cell. During this process, the centromere serves as the point of attachment for microtubules, microscopic fibers that extend from each end of the cell and pull the chromosomes apart.

"We were studying the fundamental features of the centromere that help it to do its job, when we made a startling discovery," Chan recalls. He and postdoctoral fellow Ravi Maruthachalam were studying a centromere protein called CENH3 and were trying to breed Arabidopsis plants that contained a slightly defective form of CENH3 with plants that contained normal CENH3. They expected the offspring to contain genes from both parents, which is the normal outcome of sexual reproduction. Instead, up to half of the offspring had genes only from the parent with normal CENH3.

They found that the plants had undergone a process known as genome elimination. "The upshot was we had created plants that had genetic material from only one of their parents," Chan says. The unexpected result wasn't just a scientific curiosity; it represented a whole new approach to one of the biggest challenges in plant breeding, creating true breeding varieties rapidly. This wasn’t the first time genome elimination had been found in plants, but the method using altered CENH3 was simpler and should be applicable to a wider variety of plants. "We're hopeful that we can reproduce it in any crop plant, because the protein we've manipulated, CENH3, is found in every eukaryotic organism," Chan says. (Eukaryotes include all plants and animals.)

The next step is to repeat the Arabidopsis experiments in crop plants—tomato and mustard family members such as cabbage and canola—and Chan, who can't resist a mental challenge, whether it's solving a crossword puzzle or tackling a scientific stumper, is up to the task. His appointment as an HHMI-GBMF investigator also will help to advance both basic and applied aspects of the work in crops, he says. "Working with these larger plants is more expensive and time-consuming than working with Arabidopsis. The funding will be fantastic for that."

Such practical findings haven’t slowed Chan’s interest in basic science or in centromeres. In fact, his lab is exploring the enigma of centromere evolution. "Normally, when you have something in a cell that's essential, it's very conserved in evolution, meaning it doesn't change much in terms of DNA sequences or proteins," Chan says. "But there's a paradox when you observe the centromere, because the DNA sequences that underlie the position where microtubules attach are among the most rapidly evolving features in the genome." His recent focus is understanding the functional consequences of rapid centromere evolution and its potential role in creating new species.

In all of this work, Chan sees connections between his research and the music he has loved since his teens. "Jazz is improvised, creative music, and the hallmark of the true greats is an instantly recognizable sound," he says. "In my science, I also try to do something creative and original, rather than just reproducing what others have done before."

Simon Chan is an assistant professor in the Department of Plant Biology at the University of California, Davis. He received his B.Sc. from the University of Auckland in New Zealand and his Ph.D. from the University of California, San Francisco. He has been honored with several awards, including the American Society of Plant Biologists Early Career Award and a Basil O’Connor Starter Scholar Award from the March of Dimes. He was an HHMI predoctoral fellow from 1997 to 2002.

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