PRESIDENT'S LETTER

Rob McClung

A Model Citizen

In my high school years in the late 1960s, I do not think I ever aspired to be a “model citizen” of the society I saw around me. As a matter of fact, I think being a model citizen would have been anathema to me, rather akin to the “goody two-shoes” term of derision of my younger years. It was the time of the antihero, whether Donald Sutherland and Elliot Gould in MASH, Faye Dunaway and Warren Beatty in Bonnie and Clyde, Peter Fonda and Dennis Hopper in Easy Rider, Paul Newman and Robert Redford in Butch Cassidy and the Sundance Kid, or Jack Nicholson in Five Easy Pieces. I played in a rock ’n’ roll band—what can a poor boy do? (1).

The ’60s were complex, however, and there was much more in the air than simple rebellion. The ’60s counterculture attempted to articulate many things, including a respect for the planet that many of us felt was lacking. I remember robins staggering and dying on my lawn from ingesting the incredible neurotoxic pesticides being applied around my suburban home, named Applewood for its orchards. DDT was killing loons, ospreys, and eagles. The bioaccumulation of DDT inspired a stunning poster of a woman’s breast, with a caption indicating that milk from such containers may be unfit for human consumption.

I made a trip to Sudbury, Ontario, and saw the stunted vegetation from the downwind plume of sulfur dioxide released from the huge smokestack (the Inco nickel mine is considered to be the single largest point source of acid rain, causing emissions on the entire continent). All these events evoked a visceral, emotional response—“they” (the older generation) were killing the planet—that resonated perfectly with the normal rebellion of adolescence.

In my college years, I was much influenced by Limits to Growth (2), which mathematically modeled the consequences of a rapidly growing world population given finite resources. That analysis was controversial and has been criticized for the limitations of the data sets considered, but the premise was influential, and the basic message, to me, remains fundamentally sound. Exponential growth (in population, resource utilization, and waste generation) will eventually become incompatible with a world that offers finite resources.

In college, the villain remained “they”—the older generation in power. The concepts of sustainability and stewardship seemed obvious yet were apparently absent from government policy and foreign to anyone over 30. Unfortunately (well, fortunately, actually), one of life’s inevitable progressions is that one becomes one of “them” almost before one notices. Here I am, 40 or so years on. I heat my home in winter (granted, I do use a wood stove quite a bit), and I drive a car (but a Mini Cooper with 37 mpg, not an SUV), and I recently flew to Mérida, Mexico, for Plant Biology 2008. Certainly, I have become a citizen of the society of which I was (and remain) quite critical.

One of my life’s unexpected ironies and privileges has been that at Dartmouth, I had the opportunity to engage the classes taught by the lead author of Limits to Growth, Dana Meadows, before her untimely death in 2001. My decidedly pro-GMO outlook sparked much conversation with her and her classes (both very much on the anti-GMO side), and I think we all were considerably informed by our discussions.

The dilemma of continuing growth in the face of resource limitation has been an ongoing theme of my columns. Reading the May/June issue of the ASPB News, I could not help but note that the letter Brian Hyps and I wrote (Brian was much too modest to take any credit) and published in the Washington Times on March 6 was inspired by oil passing the unheard-of $100-per-barrel threshold. Now, as the July/August issue of the newsletter moves into production, oil is around $140 per barrel and has flirted with $150!

The Washington Post recently published a commentary by Robert J. Samuelson that cited economist Jeffrey Rubin of CIBC World Markets, who predicted that oil will rise to $225 per barrel (and gasoline to $7 per gallon) by 2012 (3). In the face of these prices, it is no wonder that Americans are driving less and purchasing many fewer SUVs. Of course, conservation (i.e., reduced consumption) is a key component of any successful response to our current energy crisis, and the drive (pun intended) for sustainability should motivate any model citizen.

But I did not come to talk about either of the two types of models, citizens or mathematical, to which I’ve referred so far. My purpose today is to talk about model organisms and about an impending threshold.

In the fall of 1981, I arrived at Michigan State University in scenic East Lansing to begin study toward a PhD (I’d earlier acquired a master’s degree from Dalhousie University in Halifax, Nova Scotia, and then worked at the USDA labs in Beltsville, Md.). It was an exceptionally good time to begin to study plant genetics and molecular biology, and the Department of Energy Plant Research Lab (DOE–PRL) was an exceptional place. Chris and Shauna Somerville relocated to the PRL shortly after I arrived there, and it was clear that something exciting was germinating in their labs (as well as in a few other labs around the world). The excitement was, of course, about Arabidopsis thaliana emerging as a model organism with which to study plant biology. When I started my lab at Dartmouth, I embraced Arabidopsis as my experimental organism and finally became a “model” citizen.

Much has been said and written about Arabidopsis. Rather than paraphrase the words of others, let me simply refer the interested reader to a couple of the relevant articles that discuss its emergence as a valuable model organism (4, 5, 6).

Figure 1. Annual rate of publication about several model organisms, 1910–2006. This unpublished analysis is courtesy of Michael Dietrich, Dartmouth College, and is based on data derived from The Arabidopsis Information Resource (http://www.arabidopsis.org/index.jsp), and Flybase (http://www.flybase.org).

I would like to point out some data generated by my colleague Michael Dietrich. Mike is a historian of genetics, and a couple of weeks ago, he sent me the graph reproduced in Figure 1. He has collected data on publication rates in a number of our favorite plant models and compared them to publication rates in Drosophila. Data were drawn from The Arabidopsis Information Resource, and Flybase. Lists of publications were refined to exclude abstracts, dissertations, personal communications, supplemental material, letters, poems, book reviews, and sequence accessions.

Knowing of my love for the little weed, Mike wanted to point out the stunning increase in the rate of publication on Arabidopsis starting in the mid- to late 1980s. Arabidopsis has not yet passed Drosophila, but simple extrapolation suggests it will.

However, as with similar graphs on resource utilization, simple extrapolation may not be valid. It takes money to publish, and in the same way that Dana Meadows and her coauthors argued that resources like food and fuel would limit population growth, so too will funding rates at NSF, NIH, DOE, and USDA limit publication rates.

I do not wish to prescribe how resources should be allocated among various model plants and crop species, at least not in this letter. But I would like to draw your attention to a recent report to the National Academies authored by Jeff Dangl and colleagues (7) as well as a recent essay by Alan Jones and colleagues (8). This report and essay provide compelling testimony to the effectiveness of the use of Arabidopsis as a model organism.

In the preface to the NAS report, Dangl wrote, “Modern molecular, cellular, and developmental biology is the story of the adoption of easily manipulated model organisms that serve to provide the ‘big picture’ for a much broader set of scientific truths. Thus, the classic case of research using lab mice and fruit flies that, while of course very compelling in its own right to those scientists who do the work, is easily tied to arguments equating model organism research with breakthroughs in human health.”

The Jones et al. essay discussed some of the many discoveries with direct relevance to human health and disease that originated with research on Arabidopsis. The authors correctly assert that several processes of direct importance to human biology can be best studied in this model organism, despite the 1.6 billion years since our evolutionary divergence from plants.

The NAS report reviewed the achievements of the National Plant Genome Initiative (NPGI) and concluded that it has been “very successful by all measures applied in this study…. Far more than just genomics, the technologies and information developed by NPGI and by the parallel and complementary program Arabidopsis 2010 Project of the National Science Foundation are the primary platforms for basic research in fundamental plant science” (7). The report acknowledges the important interplay between work in Arabidopsis and in crop species and praises this synergism as “the best rationale for further and separate development of both NPGI and the independently funded Arabidopsis 2010 Project.”

In the May/June issue of the ASPB News, I argued that there was a compelling need to improve plant productivity so that we could have both food and fuel. It is hard to imagine the achievement of this goal without basic research in model organisms, including Arabidopsis. Indeed, I would argue that we will not get there without intensive exploitation of a model organism like Arabidopsis. We have lots of data, to be sure, but we do not have anywhere near enough data to argue that we understand very much at all. And one critical lesson of the past 20 years or so is that, once generated, data are almost immediately outmoded by new technologies and new means of integration.

The real strength of any model is that the intrinsic properties that make it so good are readily adaptable to emerging technologies. A model organism effectively becomes a feed-forward loop—the model facilitates new analyses. Look at the graph—Arabidopsis is soaring! But there is a catch. The funding agencies have made a very effective investment in Arabidopsis, and that investment must be sustained. Drosophila is a well-respected and well-funded (by NIH, among others) model organism, and this has allowed sustained high productivity and increasingly sophisticated biological insight.
Arabidopsis merits similar continued investment. It has proved itself to be a valuable model organism for both plant and human biology. We owe a great many thanks to those whose biological insight and leadership, whether as scientists, as administrators in funding agencies, or as congressional leaders, facilitated the development of Arabidopsis as a leading model organism.

Of course, it is also hard to imagine that there will not be synergism between work in Arabidopsis and in other plant species. We are unlikely to eat much Arabidopsis or to burn Arabidopsis-derived ethanol (or alkanes) in our cars and airplanes, so work in model organisms must be translated into crops (and into ecosystems). As the title of the Jones et al. essay makes explicit, we must maintain a diverse research portfolio if we are to achieve the goals of enhanced plant productivity and a sustainable environment.

In the final analysis, Arabidopsis has been very good for plant biology and for all biology. I am confident that its race is not yet run. Even as my own research portfolio has diversified to include Brassica rapa (perhaps only a baby step from Arabidopsis, but truly a crop), I am proud to have become a model citizen.

Rob McClung
c.robertson.mcclung@dartmouth.edu

Acknowledgments

I thank Mike Dietrich (Dartmouth College) for his wonderful analysis and Mike, Jeff Dangl (University of North Carolina), and Alan Jones (University of North Carolina) for their comments and discussion.

References

1. Jagger, M., and K. Richards. 1968. Street fighting man. From Beggars Banquet, Decca/ ABKCO. http://www.youtube.com/watch?v=qUO8ScYVeDo.
2. Meadows, D. H., D. L. Meadows, J. Randers, and W. W. Behrens III. 1972. Limits to growth. New York: Universe Books.
3. Samuelson, R. J. 2008, June 18. Learning from the oil shock. Washington Post, A15.
4. Meyerowitz, E. M. 2001. Prehistory and history of Arabidopsis research. Plant Physiology 125:15–19.
5. Somerville, C., and M. Koornneef. 2002. A fortunate choice: The history of Arabidopsis as a model plant. Nature Reviews Genetics 3:883–889.
6. Leonelli, S. 2007. Growing weed, producing knowledge: An epistemic history of Arabidopsis thaliana. History and Philosophy of the Life Sciences 29:193–224.
7. Dangl, J. L., L. Banta, R. Boerma, J. C. Carrington, J. Chory, S. A. Kay, S. Lewis, T. Mitchell-Olds, N. R. Sinha, M. Snyder, S. H. Strauss, and E. R. Ward. 2008. Achievements of the National Plant Genome Initiative and new horizons in plant biology. Washington, DC: The National Academies Press.
8. Jones, A. M., J. Chory, J. L. Dangl, M. Estelle, S. E. Jacobsen, E. M. Meyerowitz, M. Nordborg, and D. Weigel. 2008. The impact of Arabidopsis on human health: Diversifying our portfolio. Cell 133:939–943.