When I came here in 1973, I had a very broad mandate: To look at the effects of air pollution on vegetation, and to try to determine the mechanisms of those effects. It's a very, very interdisciplinary area. It's not central to plant pathology — these are not biological agents we're working on — and it's not in the mainstream of plant physiology either. It's on the edge between.

I've been doing this work since I was a graduate student in 1968, and the distance between me and what I don't know is still very short. As the years have gone by, and new questions have continued to arise, I have had to ask other people - eco-physiologists, molecular biologists, electrophysiologists, even chemical engineers - for answers that were outside my expertise. Every time I've gone into one of those areas, I've been uncomfortable. But by going anyway, I have been able to bring the insights of these others into my work. Again and again, it has changed my way of thinking.

Ten years ago, for example, I was finishing up a research program looking at the effects of ozone and sulfur dioxide on potato quality. Hal Mooney at Stanford, one of the real leaders among eco-physiologists, was doing some sulfur dioxide research with radishes. Through a common funding agent, we got together on a joint project.

I had been doing my thing, focused on the biochemistry of how ozone causes accelerated senescence - early death - of a plant's leaves. But Hal thinks about the plant as a whole. He said, "Are you sure the effect is all bad? Are you sure there isn't some benefit somewhere?" So we began looking at the whole plant, a very different context for me. I'd go out to Stanford once or twice a year to meet with Hal and other eco-physiologists, and I felt like a student again. But it was okay, because it was so expanding.

We did a series of experiments over five years and found that while the lower leaves of plants exposed to ozone were dying, there was indeed some shift of nutrients to the top of the plant. We ended up writing a synthesis paper on this kind of compensatory response. It's opened up a whole new way of thinking about the issue.

More recently, here at Penn State, I have been working with Sally Assmann, in the biology department, on how ozone affects guard cells, which are a plant's first line of defense against air pollution. We know that guard cells swell to close a plant's pores when a plant is exposed to ozone. We also know that closing pores shuts down photosynthesis. But does ozone affect guard cells directly? I had been wondering about this for a long time, but I didn't have a clue as to how to study these cells. Then Sally arrived from Harvard. How guard cells sense and respond to environmental signals like heat, light, and air pollution is her specialty. We quickly hooked up, and for the past five years, joined by additional colleagues in Israel, we have had just a dream collaboration. We're now on the verge of some important findings suggesting that ozone may directl affect guard cells; and these effects could have broad-ranging implications for the whole plant.

In both cases, making the necessary connections — across disciplines, institutions, countries — has produced rich and unexpected rewards. Certainly not all such efforts will pan out as well. When they don't, I've learned, you just have to move on.

But when they do, it changes your perspective forever.

Eva J Pell, Ph.D., is the John and Nancy Steimer professor of agricultural sciences. In July 1999 she was appointed interim Vice President for Research and Dean of the Graduate School.