National Soybean Research Laboratory Bulletin

The NSRL Bulletin is published three times a year by the National Soybean Research Laboratory at the University of Illinois, 170 National Soybean Research Center, 1101 W. Peabody Drive, Urbana, IL 61801; telephone (217)244-1706; e-mail nsrl@uiuc.edu; FAX (217)244-1707. James Sinclair, director; Robert J. Wynstra, editor; David Riecks, photographer; Lynn Hawkinson Smith, graphic designer.

Unless otherwise stated, articles may be reproduced or quoted if credit is given to the NSRL Bulletin. The National Soybean Research Laboratory at the University of Illinois is an affirmative action and equal opportunity institution.

With virtually no fanfare, a little-understood molecular process known as gene silencing has recently begun to attract widespread interest as a possible key for overcoming some of the problems that have plagued the development of commercial transgenic crops.

As part of the intensified research effort, Lila Vodkin, professor of plant genetics at the University of Illinois, is working to determine how this process of genetic regulation controls the production of compounds known as flavonoids in the soybean.

"Flavonoids are a group of compounds found only in plants, and they play very important roles as antimicrobial defense agents when plants are threatened with disease pathogens or stress conditions," she says. "These compounds also appear to have a major role in human health and nutrition, possibly even as anticancer agents in soybean food products."

Lila Vodkin, professor of plant genetics at the University of Illinois, compares genetic banding patterns for normal tan-coated soybeans and mutated soybeans with black seed coats. This work is aimed at better understanding how the process known as gene silencing controls the production of flavonoids in the soybean.

With support from the Illinois Soybean Checkoff Board, Vodkin and graduate research assistant Jocelyn Todd have focused on determining how the gene-silencing process affects expression of chalcone synthase (CHS), which is a key enzyme in the flavonoid pathway in soybeans. CHS activity is necessary for synthesis of flavonoids and is often a control point in the regulation of the pathway that produces these compounds.

"Recently we have been intensively investigating the expression of flavonoid pathway genes in the developing seed coats of soybeans that have different forms of a gene known as the inhibitor gene," she says. "Dominant forms of the inhibitor gene result in yellow seed coats, while the recessive inhibitor mutations result in seed coats that are black."

All U.S. commercial soybean varieties carry either the yellow form or the black hilum forms of the inhibitor gene. Spontaneous mutations to the recessive forms occur in most inbred soybean varieties. These can be readily recognized as black seeds occurring in an otherwise yellow-seeded variety.

Research has shown that CHS is greatly reduced in quantity in yellow seed coats, which have the dominant form of the inhibitor gene. At the same time, other enzymes in the pathway are not affected by which form of the gene is present.

"Situations such as this, where the dominant form inhibits gene activity, are not common in plants," Vodkin says. "Currently, there are very few examples of a molecular explanation for the nature of such mutations."

Vodkin's research clearly indicates that the soybean inhibitor locus exhibits naturally occurring spontaneous mutations that show the form known as gene silencing. This process of gene silencing was first described in transgenic plants where insertion of multiple copies of the same gene resulted in less rather than more expression of the inserted gene.

"A rough analogy would be finding out that one plus one doesn't always equal two," Vodkin says. "Sometimes in fact, one plus one can even equal zero."

As a result, gene silencing presents some major problems in the production of transgenic plants. This process currently is the focus of intense investigations at the basic research level and raises important concerns for the biotechnology industry.

"The molecular basis of the gene silencing mechanism is still unknown," she says. "However, our examination of the naturally occurring inhibitor locus mutations hopefully will lead to a better understanding of gene silencing and to better ways of overcoming this problem in transgenic plants."

Additional research is underway to determine whether gene silencing occurs in other tissue or only in the seed coat where the effect on seed color can be easily seen. One important payoff from the basic research on the pigment gene already has been accomplished because a major gene for cyst nematode resistance in the soybean was found to be closely linked to the pigment inhibitor locus.

"This means that we have found the closest DNA marker to date near the cyst nematode resistance gene," Vodkin says. "This marker should be very useful in cloning the cyst nematode resistance gene and following it through populations."

Ultimately, this research on gene silencing could have even broader implications for the soybean industry, especially as interest in the human health and anti-cancer effects of flavonoids continues to escalate.

"Better understanding of this unique genetic mechanism could have major implications for controlling the flavonoid pathway," Vodkin said. "Ultimately, it could be possible to use genetic engineering techniques to produce soybean varieties with more or less of a desired flavonoid for improved disease resistance or enhanced human health effects."

Sclerotinia stem rot, which is commonly known as white mold of soybean, has been a chronic problem in Minnesota, Wisconsin, Michigan, and parts of Ohio for many years. By 1992, however, this problem had spread throughout the northern range of states in the central region of the country. Even today the reasons for this sudden expansion of white mold are not fully understood but could be related to changes in cultural practices, new environments that are conducive to spread, changes in the genetic base of current soybean varieties, or genetic shifts in the white mold pathogen.

Although information is available on individual control tactics, there are critical gaps in the information base that is needed to formulate a comprehensive integrated control program. Many specific questions, such as how tillage practices and planting soybeans in narrow rows influence white mold, remain unanswered.

In an effort to fill in this information gap, researchers from six universities in the north central region recently joined forces in a project aimed at developing unified control recommendations and identifying soybean germplasm with increased levels of resistance to white mold.

Craig Grau from the University of Wisconsin serves as the principal investigator for the project, which is funded by the North Central Soybean Research Program. Participating institutions include Iowa State University, the University of Minnesota, the University of Illinois, Michigan State University, Ohio State University at Wooster, and the University of Wisconsin.

"The idea is that the combination of resistance and crop management practices can be integrated to alleviate the white mold problem in soybeans, both on a short- and long-term basis," says Glen Hartman, plant pathologist with the USDA/Agricultural Research Service and the Department of Crop Sciences at the University of Illinois.

According to Hartman, an integrated approach is essential because genetic resistance to white mold does not appear to be complete. He points to variety selection, tillage, rotation, cover crops, and row spacing as examples of practices that can be adapted to different geographic regions as means to alleviate the short-term severity of white mold.

"A long-term solution to the disease will happen only through greater deployment of available resistance and the identification of better sources of resistance," he says. "Although there is partial resistance in some available cultivars, higher levels of resistance may be available in the Soybean Plant Introduction Collection, which has not been systematically evaluated for this disease."

In addition to screening for resistance, researchers will investigate the effects of rotation, tillage practices, and cover crops on pathogen survival and inoculum density. They also will examine the subsequent effects of these practices on disease severity and soybean yield. Other research will investigate the effects of row spacing in naturally infected sites and the relationship between herbicides and white mold occurrence.

Hartman notes that this research program is based on collaboration among breeders, agronomists, and plant pathologists. Such interdisciplinary cooperation is essential to assure that management practices and variety developments are compatible with other aspects of soybean production.

"By working together, we can insure that we do not increase the potential for another pathogen or pest to become dominant," he says. "It also provides safeguards against introducing new varieties that could be susceptible to other diseases. This means we can report our findings with confidence that they will benefit both farmers with specific problems and the overall soybean industry."

With the boom in organic gardening and the widespread introduction of reduced tillage practices for both soybean and corn production, interest in biological control of insects has escalated in recent years. Yet, for many extension specialists, crop consultants, farmers, and gardeners, there has been a lack of easily accessible information on this complex topic.

As a first response to this critical need for education on biological control, a group of scientists from several universities launched the Midwest Institute for Biological Control in 1991. The institute was designed to offer a series of summer short courses on specialized aspects of biological control. Since its inception, more than 100 students have participated in at least one of the four rotating course offerings.

As the courses progressed, instructors identified the need for a teaching mechanism that could provide introductory information on biological control for all the participants before they attended the summer short course. Their attention quickly turned to the concept of developing the material in a CD-ROM format.

"The idea initially was that we were going to prepare something that served two purposes--as a primer before students arrived at the course and as a reference when they got home after the course," says Joe Maddox, entomologist with the Illinois Natural History Survey (INHS) and the Department of Natural Resources and Environmental Sciences at the University of Illinois.

As Maddox began collaborating on this project with Robert Wiedenmann, biological control expert with the INHS, it quickly became apparent that the CD-ROM format offered numerous possibilities for expanding beyond the initial concept. Especially promising was the idea of adding multiple layers of more detailed information while keeping the first layer more basic for the beginning students.

"It didn't take us long to realize that there were lots of other opportunities for using this technology," Wiedenmann says. "What's really nice is that, because we have parallel lines of information, you don't have to wade through tremendous volumes of irrelevant information to access a specific topic of interest."

The new technology provides users with the ability to move instantly between completely different topics as they explore the program. This structure allows the program designers to target their audiences as broadly or as narrowly as they want, all within the same program.

"Users can move through the program both vertically and horizontally or any combination of the two," Wiedenmann says. "Because people view things differently, the idea is to allow them different means of accessing information."

Robert Wiedenmann (left) looks on as his colleague Joe Maddox calls up interactive graphics from a new CD-ROM on basic principles of biological control. The two scientists from the Illinois Natural History Survey and University of Illinois are collaborating on the computer program as a means to overcome the critical lack of easily accessible information on this complex topic.

The CD-ROM format also provides the ability to use graphics that are interactive rather than simply reproductions of pictures from a book. In fact, work is already underway to build a library of digital images on biological control.

"One of the things that makes this format ideal for our purposes is that it is very easy to constantly upgrade or change the program," Maddox says. "New information, concepts, pictures, and graphics all can be added as soon as they become available."

With support from the Biological Control Institute, the Illinois Agricultural Experiment Station, and the Illinois Natural History Survey, work is underway at the National Soybean Research Laboratory to develop the basic program framework. Although many decisions remain about the final shape of the program, Maddox and Wiedenmann are convinced that the possibilities for its use are almost limitless.

"What started out as a directed and rather simplistic approach to preparing people for the summer short course has expanded into something much bigger," Maddox says. "In fact, there are many exciting possibilities in addition to the CD-ROM, including the idea of putting the program directly on the Internet."

The soybean is the largest oilseed crop in the world with annual production exceeding 140 million acres. This acreage produces approximately 25 percent of the world's vegetable oil supply and 60 percent of the world's protein meal supply.

But, according to Dennis F. Byron, Worldwide Soybean Research Director at Pioneer Hi-Bred International, this huge world market could become even more valuable by improving the quality and quantity of protein and oil in the soybean.

"Improving seed storage components is not trivial, and success will not come easily," Byron says. "Most often, achieving these goals will require major collaborative efforts among researchers from both the public and private sectors."

Dennis F. Byron, Soybean Research Director, Pioneer Hi-Bred International, Inc.

Byron shared these and other perspectives on the need for public and private research partnerships for soybean improvement as part of his presentation of the fourth annual George A. Fluegel Memorial Lecture at the National Soybean Research Laboratory. This event annually features a prominent member of the soybean industry and is presented in recognition of the positive impact that former American Soybean Association President George A. Fluegel made on U.S. agriculture.

This year's lecturer, Dennis F. Byron, is responsible for directing all breeding activities at Pioneer's nine soybean research stations. In addition, he assists in directing the company's biotechnology research and serves as a member of the Pioneer Soybean Product Planning Team. Prior to joining Pioneer, he served as soybean research director for Mycogen Plant Sciences.

During his presentation, Byron emphasized that both conventional plant breeding and biotechnology techniques will be required for the soybean industry to reach its lofty product development goals. At Pioneer and other companies, this means there will be increased collaboration with the public sector involving sharing of expertise and research resources.

He notes that soybean breeders will need to continue searching the world collection of soybean germplasm for improved traits. They also must use mutation breeding techniques to create variability not found in the world collection. In addition, molecular techniques will be needed to control biochemical pathways, allowing plants to produce protein and oil with improved nutritional value and function.

"These types of projects are complex and require a coordinated effort from multiple disciplines," he said. "Most companies, however, do not aspire to have all the required competencies in-house. Instead, these companies expect to access some of the required knowledge and technologies from outside sources."

He adds that Pioneer and other seed-producing companies will continue to collaborate with universities and other public institutions in development of soybean varieties with improved quality traits. His company, for example, is currently collaborating with the University of Illinois on developing high-protein soybean germplasm and with Iowa State University on developing varieties with improved oil quality.

"We do not have the expertise and resources to cover all aspects of soybean quality, so we look for collaborative opportunities with scientists at institutions such as the NSRL," Byron said. "Our soybean breeding projects also rely heavily on public researchers to evaluate germplasm from both private and public sources for traits of importance."

He points out that plant breeding and biotechnology increasingly are teamed together in new soybean product development processes. Biotechnology techniques, such as gene transformation, add even more complexity to the product development process.

"A number of technology components must come together to make the whole process work," he says. "As a result, technology delivery companies like Pioneer will continue to look to technology developing entities, such as our land-grant universities, to provide some of the information and technology components needed to make soybeans with value-added traits."

The importance of research collaborations between public and private groups is further heightened by the consolidation of biotechnology companies. This has resulted in fewer companies to supply technology, with many of the remaining companies choosing to keep their technologies proprietary.

"These circumstances provide an opportunity for universities to become more important developers and providers of technologies for companies that do not have their own strategic ties to private technology providers," he says.

According to Byron, Pioneer plans to continue its strong collaborative efforts with the public sector. These collaborations will include scholarships, contract research, and competitive grants, as well as formal and informal information sharing.

"It is essential for researchers and administrators in both the public and private sectors to understand each other's capabilities and needs," he says. "Both groups need each other to keep the soybean competitive in world markets."

Two significant events linked with the National Soybean Research Laboratory were announced during recent activities surrounding the fourth annual George A. Fluegel Memorial Lecture. Each in its own way marks a turning point in the development of the NSRL program.

First, in ceremonies prior to the lecture, the Illinois Soybean Program Operating Board announced a major endowment establishing the Soybean Industry Chair in Agricultural Strategy in the College of Agricultural, Consumer and Environmental Sciences (ACES). This generous endowment will play an important role in assisting the NSRL to fulfill its mission of providing strategic information and support for effective decision-making within the U.S. soybean industry.

The second announcement concerns my personal decision to relinquish the responsibilities of interim director for the NSRL effective on January 1, 1997. This announcement was made in anticipation of my retirement from the University of Illinois and the Department of Crop Sciences on that date.

I would like to use this opportunity to express my sincere thanks to all those who have assisted in development of the NSRL facility and program. Appreciation is due to the members of the NSRL Advisory Committee who provided the essential insight and guidance needed for establishing the NSRL program. Further compliments go out to the members of the College of ACES administration and the Administrative Advisory Committee for their helpful advice and suggestions.

Closer to home, I owe a special debt of gratitude to the faculty and staff of the Department of Crop Sciences, especially my colleagues in plant pathology. Special thanks also are due to the members of the Illinois Soybean Program Operating Board and the College of ACES Office of Research for their moral and financial support, without which the accomplishments of the last four years would not have been possible.

Even after my retirement date, I plan to remain active as an emeritus professor. I will keep working with my students to complete their graduate programs. In addition, I plan to continue my research and look forward to completing a book on integrated soybean management, which will be published as the second volume in the NSRL Publication Series.

VOL. 3, No. 3, October 1996

In This Issue