Let me start out with a disclaimer. I am not a molecular biologist. I am not really a plant scientist, although I played one as a researcher for 31.5 years at the University of Georgia (and I have some published papers to prove it!).1-2 My only formal education in plant science included an undergraduate course in Botany and a graduate class in Postharvest Physiology. Dr. Ashworth, my botany instructor, was noted for his elaborate drawings with colored chalk that were far more instructive than any illustration that could come out of a textbook. Dr. Bramlage, who introduced me to the physiology of harvested plant organs, brought enthusiasm to his lectures and imparted a love for the biological activities of common fruits and vegetables. What I remember most fondly from the botany class, however, was the visit on the first day of class by a classmate I had known in high school who came across the classroom to greet me. She soon became my girlfriend, later my fiancé, and now my wife of 45 years and counting. What I remember most fondly from the postharvest physiology class was a scientific foundation for most of my research career and an inspiration for communicating with students in the classroom.
My education continued at Gordon Conferences during summers in New Hampshire. I attended at least two conferences on Postharvest Physiology and one on Plant Senescence. My research focused on tracing the changes in quality of specific fruits and vegetables, most notably peaches and tomatoes, from farm to market. I was also studying the effect of low temperatures on the cellular physiology of susceptible fruits which become damaged if stored at refrigerator temperatures. I later became interested in measuring flavor quality and consumer acceptability of fresh tomatoes. My interests did not include GMOs, but both sets of conferences became increasingly oriented towards molecular biology. The beauty of the Gordon Conferences beyond the formal presentations was the ability to connect one-on-one with primary investigators in the field. The best way to connect with a specific scientist of interest was to maneuver a place at the meal table close to the target.
I did have some interest in the advances of gene modification to improve the flavor of supermarket tomatoes, however. Research described by Don Grierson of the University of Nottingham was directed at slowing down softening of the tomato to allow the flavor to develop and reach its peak when it hit the supermarket shelves.3 After his presentation at one of the Gordon Conferences, the session broke for lunch, and I was able to grab a spot right across a narrow dining-hall table from Dr. Grierson. I asked him about his research on inhibiting the expression of a gene for polygalacturonase, an enzyme involved in tomato softening. He had stated in his talk that his research team had inhibited enzyme activity by 10% and that they were looking to develop lines that would inhibit it up to 50%, if I recall the number correctly. I asked him, “How do you know if 10% is enough or too much?” He replied, “You see, we have a variant that inhibits activity by 10%, and we are looking at one that inhibits activity by 50%.” In other words, he wasn’t going to give me any inside information. At a meeting later that year in Tulsa, Oklahoma, I was standing at the back of a hall holding over 500 scientists to hear the answer. Even at higher levels of polygalacturonase inhibition the tomato was still becoming too soft too rapidly to allow flavor to catch up.
The following spring, I had the opportunity to travel to England and visit with Graeme Hobson who grew these famous tomatoes in glasshouses in the southern part of the country. I also travelled north by train to Nottingham. Dr. Grierson was not there but I did visit with one of his collaborators, Greg Tucker. After I returned home I pursued other contacts with research managers from DNA Plant Technology and Calgene to see if my work on consumer acceptability could enhance their genetic work. My pursuit of industry funds took me to a tomato packinghouse just outside of Chicago, an extensive set of greenhouses in Delaware and a major research center in Davis, California. My conversations with researchers at all three locations were invigorating and exciting. I was as impressed with the facilities as Mackay Jenkins was as described in Food Fight. Unfortunately, it turned out that the molecular biologists and I were operating on nonintersecting planes of thought. I don’t know how much useful information they gained from my presentations, but I was completely unproductive in finding money from them to support my graduate students.
By this time, I was becoming very frustrated. I attended a presentation at the annual meeting of IFT (Institute of Food Technologists). The speaker told us about all the great things genetic engineers were doing at modifying food crops. If food scientists would just get off their butts to help them with quality evaluation, he challenged us, everything would be great. During Q&A, I asked if they might share some of the money devoted to genetic research with interested food scientists to do what needed to be done. His response, “Next question.”
I was able to obtain a grant titled Quantification of flavor quality of fresh tomatoes from the USDA. The project involved collaboration with researchers from the University of Florida. My prime contact was Jay Scott at the Bradenton research station. He provided me with all the tomatoes I needed, none of which were GMOs. I also developed a research relationship with Elizabeth Baldwin at the USDA lab in Winter Haven who took in several of my graduate students for work on the flavor chemistry aspects of the project.4 One minor component of the project involved interaction with Harry Klee, the famous molecular biologist working on breeding the perfect tomato as featured in Food Fight and Flavor. It turned out that Dr. Klee was at point A or so in the process of breeding a perfect tomato while were somewhere down at point R at evaluating tomato flavor. Despite a few meetings and discussions, we were never able to develop any means to connect our research. During a subsequent visit to Washington as part of the Research Committee of IFT, I remember a discussion with the head of the USDA/NRI (National Research Initiative) grant program. I told him that I was working at connecting more applied studies to basic research. He paused for a minute and then said “Oh, you mean the valley of the shadow of death.” I guess that I should have taken that message as a warning.
Undeterred, Stan Kays and I took one more stab at linking food science to plant breeding. There are ways that breeders have to generate large numbers of variants with a goal of producing a single, succesful, commercial variety of a fruit or vegetable. Selecting the few winners that will go through final testing is a matter of elimination. Breeders have tests available for many attributes including crop yield, resistance to disease and stress tolerance to screen out unacceptable candidates. Unfortunately, there are no tests in this process for flavor quality. The breeder, through conventional or GMO means, can only hope that at least one of the finalists will also exhibit great flavor quality. Stan had the idea to develop a schematic that would provide a means of test criteria to allow screening of the initial variants for flavor quality. The crop we chose to use as our model was aromatic rice.5-6 We were able to cobble some money together to support this research within the university, but our efforts to obtain federal money died in Washington. The grant panels just did not believe that we could connect consumer research and plant breeding. Maybe they were right—the goal may be impossible. But, maybe we were just ahead of our time. I continue to believe that some innovative researchers with new techniques and new perspectives will link up to build a bridge between the two fields over that valley of the shadow of death.
Happy Thanksgiving to all!
Next week: A view of GMOs from within the food industry
1 Cheng, T.S., J.D. Floros, R.L. Shewfelt and C.J. Chang, 1988. The Effect of high-temperature stress on ripening of tomatoes. Journal of Plant Physiology 132:459-164.
2 Purvis, A.C. and R.L. Shewfelt, 1993. Does the alternative pathway ameliorate chilling injury in sensitive plant tissues? Physiologia Plantarum 88:712-718.
3 Smith, C.J.S., C.F. Watson, P.C. Morris, C.R. Bird, G.B. Seymour, J.E. Gray, C. Arnold, G.A. Tucker, W. Schuch, S. Harding and D. Grierson, 1990. Inheritance and effect on ripening of antisense polygalacturonase genes in transgenic tomatoes. Plant Molecular Biology 14:369-379.
4 Abegaz, E.G., K.S. Tandon, J.W. Scott, E.A. Baldwin and R.L. Shewfelt, 2004. Partitioning taste from aromatic flavor notes of fresh tomato (Lycopersicon esculentum, Mill.) to develop predictive models as a function of volatile and nonvolatile components. Postharvest Biology and Technology 34:227-235.
5 Limpawattana, M., D.S. Yang, S.J. Kays and R.L. Shewfelt, 2008. Relating sensory descriptors to volatile components in flavor of specialty rice types. Journal of Food Science 73:S456-S461.
6 Yang, D.S., R.L. Shewfelt, K-S. Lee and S.J. Kays, 2008. Comparison of odor-active compounds from six distinctly different rice flavor types. Journal of Agricultural and Food Chemistry 56:2780-2787.
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