This is a golden age for plant biology, and Gloria Coruzzi is one of the leaders of a new wave of researchers using modern methods of molecular biology to answer questions about how plants work. Dr. Coruzzi, a lifelong New Yorker, is a Carroll and Milton Petrie Professor of Biology at New York University. Her research applies genetic analysis and DNA manipulation to dissect the regulation of plant metabolism, especially the synthesis of amino acids, a process of great importance to agriculture and human nutrition. Professor Coruzzi is also strongly committed to promoting modern plant biology in the undergraduate curriculum; she teaches in NYU's introductory biology course and provides opportunities for undergraduate students to gain research experience in her lab. Gloria Coruzzi's dual achievements as a scientist and an educator confirm that excellent research and inspiring teaching are complementary activities of university faculty.
Tell us how your interest in science and plant biology developed.
I was interested in science way back, and as a high school student I did research at Rockefeller University on a project using rats as a model to study obesity. I remember one day chasing a fat rat around the lab and making an almost subconscious decision not to work on animals. By the time I did my Ph.D. at NYU Medical School, I was interested in molecular and cell biology and worked on mitochondrial DNA in yeast. It was about the time DNA sequencing was invented, and we sequenced the mitochondrial DNA and discovered that yeast mitochondria use a different genetic code. I began working on plant molecular biology as a postdoctoral researcher at Rockefeller University. At the time, scientists were saying that plant genes couldn't be cloned, and then we cloned some of the first plant genes and started to demonstrate how they are regulated by light. At the time I was what is called a "gene jock." I could isolate DNA and sequence it. Plants were just organisms to grind up to get out their DNA. But I've come to appreciate plant biology, and rather than just studying a gene, my lab now studies how a gene works in the context of the whole plant. The model organism we work on is Arabidopsis, which makes it possible for me to work on plants in New York City and which has brought plants back into many biology departments.
Arabidopsis is a tiny weed in the mustard family. How did it become such an important model organism in plant research?
It was a problem for plant biology, especially at the biochemical level, that researchers traditionally worked on such a diversity of species. For example, somebody purifies an enzyme from one plant, and then another lab purifies the enzyme from a different species, and because everyone is working on different species, there may be slight differences and you never come to a synthesis of what's happening in a particular biochemical pathway within any single organism. So, there are benefits in focusing research on a single species. Arabidopsis has become to plant research what E. coli is to microbiology or Drosophila is to animal research. As a model organism, one advantage of Arabidopsis is that it has a relatively short generation span of four to six weeks, which makes genetic research easier. The plant also has a relatively small genome, and researchers have already sequenced about 20% to 30% of the Arabidopsis genome. This is a treasure trove of information for biologists. Genes for enzymes that we could never purify are popping out, and some of these genes have homology to genes in E. coli or humans. It's really a renaissance time in biology to be able to make these kinds of connections between organisms. Arabidopsis has brought plants back into biology departments that had almost eliminated plants during the early days of molecular biology. Here at NYU, biologists work on diverse organisms, but mostly at the cellular and molecular levels, and so we can all talk to each other, whether we're working on plants, or worms, or bacteria, or flies, or humans. Molecular biology is bringing biology departments back together. There are still plant biologists that say, "Arabidopsis is just a weed with no commercial value," but I think we're showing that genetic analysis is revealing certain processes that are common to all plants. Arabidopsis has also been a good model to show that plants can be genetically engineered. One of the reasons I went into plant biology is that I believed transgenic plants would have an important impact on society.
Producing transgenic plants involves moving genes from one organism into another. Give us an example from your current research.
We're studying how plants take inorganic nitrogen and convert it to organic form, such as amino acids. Gardeners know that nitrogen is an important element that limits plant growth, but I thought it would be possible to engineer plants to assimilate more nitrogen into organic compounds. When we started, there was really nothing known about the genes involved in amino acid biosynthesis in plants. One possibility was that plants just make amino acids continuously, with no regulation. But we discovered that light regulates synthesis in either a positive or a negative way, depending on the amino acid, by regulating transcription of genes for the metabolic pathways that assimilate nitrogen into organic form. We've been studying different mutants to dissect the molecular components of this sensing mechanism. Also, the amino acids themselves turn off transcription of the genes for their synthesis when the plant has made enough of those amino acids. This is very reminiscent of regulation in bacteria and yeast. We've screened for Arabidopsis mutants that can't sense excess amino acids. We have also altered this gene regulation by making transgenic plants in which nitrogen-assimilatory genes are continuously expressed. In some cases, we're successful in getting plants to actually assimilate more inorganic nitrogen into organic form because, I think, we've impaired the feedback mechanism that normally shuts off further assimilation once the plants have made enough. I believe we are able to improve on Mother Nature, because Mother Nature's modus operandi is for the plant just to live and reproduce, not to make a bigger plant with seeds that are more nutritious for humans. Transgenic plants may enable farmers to grow crops with higher yields of organic nitrogen and other nutrients.
You mentioned earlier that you first tasted research as a high school student. Tell us more about that.
I was a student at Hunter College High School, a public magnet school in New York City that at the time was an all-girls school. It wasn't a science magnet school, but was based more on literature and history, which is what women were supposed to be interested in. But there was a subgroup of us that said, "Hey, we want to do science," and we kind of broke the mold. We did internships in our senior year, and since the school was very close to Rockefeller University, I found myself there in the lab studying obesity. Although I realized that animal research was not my thing, working in a lab really changed my life and convinced me that I wanted to do research. The biology I had read about started to jell, and the experience changed the way I thought about science. I continued research as an undergraduate at Fordham, working on a botanical project and learning electron microscopy at the New York Botanical Gardens, and that experience just totally affirmed my interest in science. I also worked one summer at the Public Health Research Institute, and that was my first foray into yeast genetics. I was hooked.
Is that why you now include high school students and undergraduates in your own lab?
Yes. The high school students are very smart, but they also have to be good with their hands because working in a lab is a combination of being smart and dexterous. Some of my best high school researchers are musicians, which requires dexterity. We also have very smart undergrads. Some are thinking about graduate school in science, and others want to go to medical school, but even the pre-med students benefit from the experience in a plant biology lab because the kind of research transcends the organism. Mapping a gene is the same in plants and animals, and so studying a mutant gene in Arabidopsis helps students understand how disease genes are studied in humans. The students learn genetics and molecular biology, and they have a window into the future of biotechnology and medicine. Whenever high school students or undergraduates are significantly involved in a project,I encourage their co-authorship on research articles. It gives them a sense of empowerment, and it's just the fair thing to do.
Can we include some of your undergraduate students in the interview? I think other students will be interested in their experience.
Yes, I'd like you to meet two of my undergrads, Dimitrios Bliagos and Cliff Ransom. (Note: Dimitrios and Cliff are the students with Dr. Coruzzi in the photo on p. 668.)
Dimitrios, tell me a little about yourself, about your work in Dr. Coruzzi's lab, and about your plans for the future.
I was born and raised in Brooklyn, and now I'm a pre-med in my junior year here at NYU. I took the MCAT last week. I think I did all right, and I'll apply to medical school in the summer.
Why do you want to become a physician?
It started in high school. I liked biology, and first I wanted to be a biomedical engineer. But I didn't really like physics, and so engineering wasn't a good choice. During my senior year in high school I kind of zoned in on the biomedical more because my AP bio teacher stressed medical applications of physiology and other topics. Then I volunteered at St. Vincent's Hospital, and that was the final push.
What led you to undergraduate research?
I started looking for labs in my sophomore year because I really wanted to go beyond what I was learning in class. The theory I learned in class was very important and we went into different lab techniques in detail, but it didn't really reflect reality. In class, you do a procedure, and you get a certain result, but I see now that it's not so easy to select a gene clone or to get this working or get that working. My first project here was to map the genes for two of the enzymes involved in synthesis of the amino acid glutamine in Arabidopsis. I didn't realize that science is so involved in terms of the amount of work you have to do get the results, and I didn't understand that at the molecular level, working with plants isn't much different than working with animals and that what we're doing here with plant genes relates to what is going on in medical research. Now I think, "Wow, I could use these techniques to map a gene for a human disease."
Cliff, are you working on the same project?
I'm also working on glutamine synthesis, but a different aspect. I'm working with transgenic plants and selecting for mutants that can't sense glutamine and continue to make it because there is no negative feedback.
Tell us about your background and your plans.
I'm from Baltimore, and I came to NYU because it's very strong in molecular biology. I'm a senior now. I'll take a year off from school after I graduate, and then I'll probably go to grad school. I just finished my GREs. I also work at the New York Botanical Garden and really like that, so maybe I'll combine molecular biology and plant systematics.
How does Dr. Coruzzi pick the undergraduate students who work in her lab?
We have to initiate it by asking if there are any available positions, and then Dr. Coruzzi and a postdoc interview us to be sure that we're interested in the lab's work and that we work hard. Then I guess she asks for recommendations from our professors.
Most of the students who read this textbook are in their first or second year of college. Now that you're upper-division students in biology, what advice can you share?
Dimitrios: I just have to say to have a blast with biology, because if you don't try to get into what you're being taught and what you're reading, you are really not going to do very well. It's very important to get involved in learning and give it your all.
Cliff: I think in an introductory course, it's easy to get overwhelmed because you cover so many different fields of biology. But I think you can use that experience to choose one or two of the areas that interest you the most, and go with them after the first year, because it's impossible to take on the whole realm of biology. You need to kind of set a focus and let that guide your path.
Thank you, and best of success in your future studies.