AgBioResearch News


Researchers Discover Mechanism Protecting Plants Against Freezing

New ground broken by an MAES researcher helps explain how plants protect themselves from freezing temperatures and could lead to discoveries related to plant tolerance of drought and other extreme conditions.

Christoph Benning

"This brings together two classic problems in plant biology," said Christoph Benning, MAES biochemistry and molecular biology scientist. "One is that plants protect themselves against freezing; scientists long thought it had something to do with cell membranes but didn't know exactly how. The other is the search for the gene for an enigmatic enzyme of plant lipid metabolism in the chloroplasts, shedding light on how cell membrane building blocks are made."

In an article published online by the journal Science, Benning and then-doctoral degree candidate Eric Moellering and technical assistant Bagyalakshmi Muthan describe how a particular gene in Arabidopsis thaliana, common mustard weed, leads to the formation of a lipid that protects chloroplasts and plant cell membranes from freeze damage by a novel mechanism.

Working on his dissertation project under Benning, Moellering identified a mutant strain of Arabidopsis that can't manufacture the lipid and linked this biochemical defect to work done by others who originally described the role of the gene in freeze tolerance but did not find the mechanism.

"One of the big problems in freezing tolerance or general stress in plants is that some species are better at surviving stress than others," Moellering said. "We are only beginning to understand the mechanisms that allow some plants to survive while others are sensitive."

There is no single mechanism involved in plant freezing tolerance, Moellering added, so he can't say that his findings will lead anytime soon to genetic breakthroughs making citrus or other freezing-intolerant plants able to thrive in northern climates. But it does add to the understanding of how plants survive temperature extremes.

Much plant damage in freezing temperatures is due to cell dehydration -- water is drawn out as it crystallizes, and the organelle or cell membrane shrivels as liquid volume drops. Lipids in the membranes of tolerant plants are removed and converted to oil that accumulates in droplets, the researchers said, retaining membrane integrity, keeping membranes from fusing with one another and conserving the energy by storing oil droplets. With rising concern globally about water supplies and climate change, scientists see additional reasons to understand the ways hardy plants survive.

The research, funded by the U.S. Department of Energy Office of Science-Basic Energy Sciences and the Michigan Agricultural Experiment Station, also leads to speculation that freezing itself can prompt cell proteins directly to change the composition of the membrane, without activation by gradual acclimation. That has been a major focus in the plant freezing tolerance field, the researchers said.

"This opens a huge door now for people to do this kind of research and to redirect researchers," Benning said. "There are lots of them out there trying to understand cold, salt and drought tolerance in plants, and we've given them a new idea about how they can approach this problem mechanistically."

Research May Lead to New Lung Cancer Treatments Alison Bauer

An MAES researcher is analyzing the immune system's ability to protect the body against lung cancer.

The results of work by Alison Bauer, MAES pathobiology and diagnostic investigation scientist, are expected to provide new approaches to prevent, identify and treat lung cancer. The disease is the leading cause of cancer-related death in Michigan and the country.

"Chronic inflammatory lung diseases such as asthma and chronic obstructive pulmonary disease are risk factors in the development of lung cancer," Bauer explained. "However, activation of certain components of the immune system -- namely the part of our immune system that responds first to an injury, or the innate immune system -- may provide protection against lung cancer development."

Previous research has determined that farm and textile workers exposed to elevated levels of a bacterial component called endotoxin are at a reduced risk of developing lung cancer, Bauer explained. After being introduced to the body, endotoxin binds to a specific protein on cells known as "toll-like" receptors; these receptors are involved in innate immunity. The primary receptor binding endotoxin is called toll-like receptor 4 (TLR4).

Bauer and her team have previously shown that TLR4 acts in a protective manner against the development of chronic lung inflammation and lung cancer in mice. That research was published last year in the journal Molecular Cancer. This project will further investigate how and why TLR4 acts in a protective manner, focusing on the cells involved in the inflammation process in mice models.

Bauer also will look at intercellular communication and growth factor regulation. The team will investigate the role of these pathways in TLR4's protective effects. In other cancers TLR4 is required for some chemotherapy drugs to be effective.

This research is funded by a $720,000 grant from the American Cancer Society.

Gut Microbes May be Therapeutic Targets for Food-borne Diseases

At any given time, trillions of tiny microbes -- some helpful, some harmful -- are living on and in humans, forming communities and outnumbering the body's own cells by tenfold.

Linda Mansfield

Using a $7.3 million federal grant that establishes a new cooperative research center at MSU, a group of investigators is studying the microbes that live in our intestines, analyzing the role they play in food- and water-borne illnesses that kill millions of people each year worldwide.

MSU's Enterics Research Investigational Network (ERIN) is one of four such U.S. research centers being funded by five-year grants from the National Institutes of Health's National Institute of Allergy and Infectious Diseases. It is led by MAES microbiologist Linda Mansfield. The team is looking at the enteric microbiome -- all the microbes that live in the human gut.

"Our long-term goal is to develop new interventions and treatments for food- and water-borne diseases; we want to know what makes people more susceptible or more resistant to enteric diseases," said Mansfield, whose group is focusing on illnesses caused by E. coli, Salmonella, Clostridium difficile and Campylobacter, among others. "Evidence suggests that the enteric microbiome profoundly affects our health and disease susceptibility and may be a new preventive and therapeutic target."

Enteric diseases, which are primarily caused by food- and water-borne pathogens, are the leading cause of acute diarrheal illness, which despite concerted efforts remains a continued threat in the United States, particularly among children.

Overall, investigators from the colleges of Veterinary Medicine, Human Medicine, Natural Science and Engineering as well as the Michigan Agricultural Experiment Station are taking part in the project. The research team will be looking at three specific areas:

  • Microbial ecology and pathogenesis: Led by MAES microbiologist Robert Britton, researchers will use a bioreactor model, made by MSU engineers, and mice to study communities of microbes and investigate whether reduced diversity in those communities -- which can be caused by antibiotics -- allows pathogens to take hold. "Although most of us think bacteria are bad, the 10 trillion bacteria that inhabit our gut play some very important roles, one of which is to keep bad bacteria from flourishing in our intestines, causing disease," Britton said. "What we hope to learn is which bacteria or communities of bacteria can protect us and how we can use this knowledge to create new therapies and treatments."
  • Host response: Led by Mansfield, researchers are trying to find the link between enteric disease caused by Campylobacter jejuni (a food-borne bacterium often found on poultry) and autoimmune disorders that are rapidly increasing in the United States. Nervous system autoimmune diseases such as Guillain Barré syndrome and Miller Fisher syndrome have been associated with recent Campylobacter infection. These diseases can cause paralysis and death, yet researchers do not know why, Mansfield said. "Our goal in this project is to understand the causes and to develop preventions and cures," she said. "We believe it will also provide insights into how other autoimmune diseases begin."
  • Clinical research: Led by molecular epidemiologist Shannon Manning, researchers will study fecal samples taken by the Michigan Department of Community Health to determine how infection with various pathogens (such as E. coli) alters the types of microbes present in the intestine. The microbial communities in patients with disease will be compared with communities in exposed individuals without disease. "Our hope is to identify potentially beneficial microbes, microbial communities and/or microbial byproducts that can be used to prevent or treat disease," Manning said.

MSU's ERIN cooperative research center continues and builds on the work started by the Microbiology Research Unit scientists. That unit is a research component of the National Institutes of Health's Food and Waterborne Integrated Research Network. For more information, visit the MRU web site.

Do Online "Advergames" Promote Child Obesity?

Though many factors contribute to childhood obesity, one of the more potentially prominent yet less-studied aspects is what are known as "advergames" -- online games that often promote less-than-nutritious food products to children.

At Michigan State University, a team of researchers will be using a National Institutes of Health grant to determine how these games affect children's eating habits and, ultimately, their health.

Advergames are not ads per se, said Nora Rifon, a professor in the MSU Department of Advertising, Public Relations and Retailing. They are games that have brands embedded in them -- sometimes subtly, sometimes not so subtly.

"It may be that children playing these games aren't at all aware that they're an attempt to persuade them to really like the brand," Rifon said.

typical Lucky Charms box front

The games may vary from a role-playing game in which the child game player acts as Lucky Leprechaun and collects charms resembling the marshmallows in Lucky Charms cereal to a basketball-shooting game in which Mr. Peanut is a logo on the basketball floor.

But beyond the subliminal messages that the advertisers get across, the larger question is how these ads affect a child's eating habits.

"We have very limited knowledge of how children respond or react to advergames in ways that influence their food preferences, their brand preferences and their eating habits," said Elizabeth Taylor Quilliam, MAES advertising, public relations and retailing scientist and a member of the research team.

The U.S. Centers for Disease Control and Prevention says childhood obesity has more than tripled in the past 30 years. The prevalence of obesity among children ages 6 to 11 years increased from 6.5 percent in 1980 to 19.6 percent in 2008. The prevalence of obesity among adolescents ages 12 to 19 years increased from 5 percent to 18.1 percent.

"This year's White House report on childhood obesity is consistent with the idea that food marketing is a contributor to the problem," Rifon said. "It's not the sole cause. But there is enough history in other types of advertising of food to children to believe that it does influence them.

"Ultimately, our hope would be to take those techniques that are effective in selling less-healthy food to kids and apply it to healthy food and healthy lifestyles."

During the two years of the study, the researchers will observe children playing the games and note how children of various ages respond to the games and how they process the information to form brand attitudes and preferences.

Pest-resistant Soybeans Grow Out of MAES Lab

Two lines of pest-resistant soybeans painstakingly developed by an MAES scientist promise healthier harvests for growers and a little green for the university, too.

Dechun Wang

"Sparta -- the Soybean Aphid Shield" is the new trade name for genetics developed by Dechun Wang, MAES soybean breeder and crop and soil sciences researcher. He tested approximately 2,000 strains of soybeans for their ability to withstand aphids and isolated four with different resistant genes. From those he developed germ plasm and bred varieties suited to Michigan's short growing season.

"The final goal," Wang said, "would be to have one variety that has all those resistant genes," maximizing protection against various biotypes of aphids and perhaps other pests such as Japanese beetle.

Soybean aphids suck plant sap and secrete a sticky substance that promotes growth of sooty black mold. After they sprout wings, the aphids can speed the transmission of plant viruses. Fifteen generations of aphids can live on a soybean plant in the summer; the eggs overwinter on nearby buckthorn.

"In the field, we will inoculate a plant with just two aphids, and the entire plant will be totally covered by aphids in a few weeks," Wang said. "It takes aphids just five days to produce more babies -- aphids are born pregnant, so the regeneration cycle is incredibly fast."

Soybeans have been cultivated in Asia for thousands of years but only since 1904 in the United States, where they're mainly processed into animal feed and vegetable oil. Tiny soybean aphids, also native to Asia, were first identified in Wisconsin in 2000 and quickly spread to most soybean-growing areas until mostly controlled with chemical pesticides. Unchecked, aphids can reduce yield by 50 percent, but one pesticide application can increase production costs by 10 percent and also kill beneficial insects.

"Pesticides have really been our only answer until this new host plant material," said Keith Reinholt, field operations director for the Michigan Soybean Promotion Committee (MSPC). His group has funded Wang's research since 2002 with about $250,000 per year from grower assessment revenue, earning it first claim on licensing rights after MSU patented the resistance technology.

The germ plasm is generating interest among seed companies, which will use it to improve their varieties. The MSPC grower board will earn royalties from the sale of seed company varieties containing the trait. A portion of those will come back to MSU, which will in turn distribute royalties to Wang, the College of Agriculture and Natural Resources and the MSU Foundation.

"With one exception, all the major soybean genetics companies have licensed his germ plasm because the level of resistance to soybean aphids is very high," said James Kells, chairperson of the Department of Crop and Soil Sciences. "We're very excited about this technology, and we see great potential for commercialization and impact on soybean growers in Michigan and elsewhere in the United States."

Wang's research also is supported by the Michigan Agricultural Experiment Station.

Insecticides Can Affect Wild Bee Populations, MAES Research Shows

Fruit and vegetable growers all over the country rely on pollinators -- mainly bees -- to produce crops from blueberries to almonds. In addition to managed honey bees, wild bees that live in and around crop fields also provide pollination services.

bee in flowerTo help growers make pest control choices that conserve these valuable native pollinators, MAES entomologist Rufus Isaacs and entomology postdoctoral scientist Julianna Tuell studied how wild bee populations are affected by pest management programs in highbush blueberries. The research is published in the June issue of the Journal of Economic Entomology.

During crop bloom, growers avoid using insecticides or use only bee-safe products to ensure that pollinators are protected. After bloom, honey bee colonies are removed from the fields, but wild bees stay in the fields.

"A rich wild bee community can be present before, during and after blueberry bloom, with more than 100 species of wild bees found in these fields," Tuell said. "Of these, approximately 10 species are present in high numbers and consistently pollinate blueberries."

"Michigan is the leading producer of blueberries in the world, and this crop is very dependent on pollination for good yields," Isaacs added. "It also faces some important insect pest challenges. This provides a great opportunity to test the hypothesis that insecticide applications made when the crop is not in bloom affect the wild bee community present during the bloom period -- when bees are most important to the crops and to the growers."

Tuell and Isaacs developed a risk index to quantify the relative risk to wild bees from insecticide applications to blueberry fields and then analyzed the relationship between the index and the abundance, diversity and species richness of wild bee communities over three growing seasons. The study also evaluated the stability of the wild bee population.

In the last two years of the study, bee abundance and species richness declined with increasing insecticide risk index values. Bee diversity declined only in the first year.

"The results indicate that wild bee communities are negatively affected by increasingly intensive chemical pest management activities in crop fields," Tuell said.

She said that studying wild bee populations is important because it can help growers make informed decisions about their pest management program that will result in more sustainable crop pollination.

"Most insecticides are applied after the crop is finished blooming," she said. "Growers who rent honey bee hives know to avoid spraying insecticides until after hives are removed. Many native bees live in the ground and nest in crop fields or in field margins, where they are likely to come into contact with postbloom insecticides."

Using the scientists' results, growers can make more informed choices about how to manage pests while continuing to get benefits from wild bees.

"Growers can reduce the toxicity and amount of insecticide they apply for pest control, and they can make adjustments in application timing," Tuell said. "More focused spraying that targets only pest-infested areas also is expected to improve the overall farm environment for bees. Our data suggest that reducing the risk of pest control programs to bees will help conserve populations of these beneficial pollinating insects that are active during crop bloom."

"With fruits and vegetables an increasing component of the nation's diet and honey bee colonies continuing to face challenges, it makes good sense to find strategies to help promote wild bees on farmland," Isaacs said.

MAES Researcher Tapped Twice for Bioenergy Expertise Bruce Dale

Bruce Dale, MAES chemical engineering and materials science researcher, was recently asked to lend his expertise to two high-level efforts aimed at advancing renewable energy technologies.

Dale, an internationally known leader in exploring alternatives to fossil fuels, was invited to serve as an expert reviewer for the draft International Panel on Climate Change Special Report on Renewable Energy Sources, an 11-chapter document that addresses various renewable energy technologies and their contributions to lessening the effects of climate change. Dale, one of eight reviewers to comment on the bioenergy chapter (chapter 2), found the report's findings in this area quite favorable.

"World energy use is about 500 exajoules annually [one exajoule equals the energy produced by 160 million barrels of oil] -- that's a very large amount of energy," Dale said. "What the report says in its current draft state, and what I think it will say when it comes out later this fall in final form, is that bioenergy has the capacity to meet a very large fraction of that 500 exajoule demand in a climate-friendly way. I think people are always concerned about whether there is enough land to generate energy as well as food and fiber. This report says yes, there is. I strongly agree with that finding."

Dale also was confirmed as a member of the Biomass Research and Development Technical Advisory Committee for the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA). The committee will give advice to the DOE and the USDA about how to structure their bioenergy research and development portfolios. Dale's appointment extends through 2012 and is renewable for another term.

Dale said that participating at this level gives him the opportunity to help guide national policy on and funding for bioenergy and to inform the research that MSU does in this area.

"It's a 'virtuous circle' of feedback," Dale said. "We have many really good people at MSU working on various aspects of bioenergy. Participating on this committee not only allows me to reflect to the committee the relevant work that we're doing at MSU, which can then be factored into the committee's recommendations, but provides a way for me to communicate to my colleagues what the emerging research priorities of the DOE and the USDA are so that we can prepare and act appropriately."

"We are very pleased to see Bruce recognized for his outstanding research and leadership," said Steve Pueppke, MAES director and MSU associate vice president for research and graduate studies. "He is a testament to the high caliber of researchers with whom we are privileged to work. His participation and contribution at this level increase the credibility and visibility of the innovative, leading-edge research conducted by MAES and MSU."

MAES Biochemistry Scientist Receives Galliard Medal

Christoph Benning, MAES biochemistry and molecular biology researcher, received the Terry Galliard Award at the 19th International Symposium on Plant Lipids in Cairns, Australia.

Benning was recognized as an outstanding scientist who continues to make highly significant contributions to the field of plant lipid research. Benning and his research partners identified novel genes encoding enzymes of sulfolipid, galactolipid and betaine lipid biosynthesis in bacteria, plants and algae. His work enables scientists to understand the biosynthesis of these lipids.

Many of Benning's findings have been patented, and some are beginning to be licensed to biotech companies for the development of novel crop plants. Benning has isolated the gene for a transcription factor regulating seed oil biosynthesis in plants. He discovered the remodeling of membranes following phosphate deprivation in plants and is working on uncovering the mechanisms of lipid trafficking in plant cells.

The Terry Galliard Award is named after the founding organizer of the International Symposia on Plant Lipids, which began in 1974 in Norwich, Great Britain. Galliard worked as a postdoctoral researcher in the laboratory of Paul Stumpf, one of the early centers of plant fatty acid and lipid research in the United States. Michigan State University's John Ohlrogge was also a postdoc in the Stumpf laboratory and is a previous winner of the Galliard Medal.

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