Research


Publications | Thesis / Dissertations | Mississippi Agricultural and Forestry Experiment Station


Research progress in the Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology is focused on topics to advance agriculture and public health in Mississippi, the southern region and the nation. The departmental faculty addresses a wide-range of research topics ranging from pest and plant interactions, human diseases and public health, commodity improvement (e.g., rice, cotton, corn, biofuels, etc.), taxonomy and systematic biology, environmental toxicology, molecular biology and pharmacology.

Biochemistry and Molecular Biology

Advancing Amphibian Populations Through Reproductive Research

Advancing Amphibian Populations Through Reproductive Research

Amphibian population declines are being reported across the globe at an alarming rate. Disease, climate change, pollution and habitat destruction all contribute to what is thought as the biggest mass extinction event since the demise of the dinosaurs. Scientists worldwide are stepping in to try and rescue threatened species from the risk of extinction, including a collaborative team from Mississippi State University and the Memphis Zoo.

Scientists with the MSU Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology are attempting to increase populations of a number of vulnerable species held in captive breeding programs, including one of the most critically endangered species in North America—the Mississippi gopher frog (Rana sevosa). Only 125 adults are thought to remain in a single pond in Harrison County, MS. Thus, captive assurance and breeding colonies being established at MSU are necessary for reintroduction and recovery programs. Unfortunately, encouraging frogs to mate naturally in captivity is not always easy as they rely on seasonal cues to stimulate breeding behavior, which can be difficult to replicate in artificial environments. Instead, assisted reproductive technologies, such as exogenous hormone administration, are used to bypass these cues and induce the production and release of sperm and eggs for in vitro fertilization. The ability to collect gametes in this way also allows researchers the opportunity to investigate protocols for the long-term frozen storage of sperm and embryos through cryopreservation. Development of successful gamete freezing techniques would facilitate the genetic management of captive populations and provide a genome resource bank as a security measure against loss, ensuring the long-term conservation of threatened amphibian species.




Developing Reproductive Technologies for Salamanders

Developing Reproductive Technologies for Salamanders

Almost 50% of salamanders worldwide are currently threatened with extinction, making them the most threatened order of amphibians. Scientists at MSU, in partnership with the Memphis Zoo, are dedicated to improving Amphibian Reproductive Technologies (ART) in the hopes of increasing the breeding success of endangered salamanders due to poor reproductive success in captive assurance colonies and the growing loss of genetically valuable founders.

Model species like the tiger salamander (which can grow up to a foot long!) are being studied to improve reproduction protocols. These protocols will initially be applied to four targeted endangered salamander species native to the United States. Most ART research to date has been focused on frogs and toads; hence, little is known about the reproduction of salamanders, resulting in a wide open field for learning more about their reproductive ecology.

When successful, this research could lead to the breeding and release of captive born salamanders to the wild in order to bolster threatened populations. This unique partnership between the Memphis Zoo and MSU are creating opportunities for graduate students, undergraduates and post-doctoral fellows to get experience at the cutting edge of basic and applied science with conservation impacts.




Luminating Infections in Pregnant Mares

Luminating Infections in Pregnant Mares

Infections are the leading cause of abortion, stillbirth and preterm delivery in mares. MAFES scientists have developed a new approach to understanding the infection process in pregnant mares by using biophotonic imaging and modified bacteria with luminescent characteristics. In other words, the technique allows researchers to capture real-time pictures of glowing bacteria as they spread through a mare's body. The method allows scientists to track pathogens in a minimally invasive procedure.




MSU professor finds pandas may aid biofuel production

MSU professor finds pandas may aid biofuel production
MAFES scientists are looking to "panda poop," or microbes in panda excrement that breakdown woody materials, as a possible means to biofuel production. Scientists recently discovered that microbes in panda feces are strong enough to break down the toughest plant materials. Panda poop might help overcome one of the major challenges to producing biofuels: breaking down the raw plant materials used to make the fuels.

The findings have garnered national attention as the reproduction of these microbes could contribute to developing alternative fuels that don't interfere with food crops and could also save a great deal of money. One of the most expensive processes in making biofuels is the pretreatment, where sugar polymers are chemically treated so that they can be used to make ethanol or oil. If you can insert a microbe that does that naturally and efficiently, production costs for alternative fuels would be cut tremendously.




MSU researcher's study leads to swamps, 'gators'

MSU researcher

A Mississippi State University biologist's fascination with crocodiles has brought together researchers from the United States and Australia to study the genetic building blocks of a reptile order. In the process, they hope to discover ways to conserve endangered animals, harness the antibiotic properties of alligator blood and isolate the genes that determine gender.

Ray recently received funding from the National Science Foundation for a collaborative project with other scientists involved in crocodilian research. Each researcher hopes the genetic information stored in the crocodilian genome will answer different questions. Ray is most interested in the role DNA plays in the body shape of all crocodilians.

Such significant genetic information could have an impact on wildlife conservation, including ways to preserve one of the research subjects, the gharial. This crocodilian is visibly different from its relatives, with completely webbed rear feet and a long, tapered snout that ends in a soft bulbous nose in males of the species.




Resist and Detect

Resist and Detect

MAFES scientists Dr. Xueyan Shan, assistant research professor in the Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, who is working on identification of resistance genes in corn for aflatoxin reduction, explains why simply cooking food contaminated with aflatoxin or processing isn't an option.

"Aflatoxins are resistant to heat, milling, and chemical treatments and are not affected by processing or cooking. The removal of aflatoxins from contaminated corn products is very difficult. Once corn is contaminated very few detoxification and utilization options are available," Shan explained.

While researchers have explored various methods for either removing aflatoxin from corn, or preventing it from forming in the first place, the answer may lie in bolstering the corn's ability to resist aflatoxin.

"Breeding corn lines resistant to A. flavus infection is the most promising and exciting alternative. Characterization of naturally occurring resistant varieties of corn will greatly facilitate the breeding of resistant corn hybrids. To date, significant levels of corn host resistance to aflatoxin accumulation have been obtained in corn inbred lines such as Mp313E and Mp715, which were developed by the USDA-ARS Corn Host Plant Resistance Research Unit in Mississippi. However, the resistance needs to be integrated into elite corn lines to achieve high yields of corn," Shan said.

Breakthroughs in gene sequencing technology have allowed scientists to identify exactly which genes carry resistance. They hope to then use CRISPR technology, which allows scientists to edit the genome of an organism to produce specific traits. "Our next steps are to identify the functional resistant genes in the major corn quantitative trait loci, or to identify the multiple genes that impact resistance, for precision breeding. Candidate genes will be selected for application of CRISPR techniques," Shan explained.




Snap, Crackle, Pop! Conversations in a Rice Cell

Snap, Crackle, Pop!  Conversations in a Rice Cell

Do you remember commercials for Rice Krispies cereal? They featured the elf-like characters Snap, Crackle, and Pop who were named after sounds the cereal reportedly makes when milk is added. Dr. Zhaohua Peng does not study Rice Krispies, but his research group is studying the molecular "conversations" that occur between a rice cell wall and its nucleus. The cell wall protects the cell and gives it rigidity. If the cell wall is removed from a rice cell, a new cell wall is synthesized. The rice nucleus contains chromatin, a mixture of proteins and DNA. The genetic information of each rice cell is stored within its genes (coded in its DNA), and which genes within chromatin are active is controlled, in part, by the way that chromatin within the nucleus is packaged. Dr. Peng and his research group have shown that removal of a rice cell wall results in substantial changes in the organization of the chromatin within the nucleus. This suggests that when the nucleus "learns" that the cell wall has been removed, it undergoes major chromatin restructuring, presumably to allow those genes involved in cell wall synthesis to be utilized in the process of cell wall resynthesis. It is unclear how removal of the cell wall is detected by the cell and how the message, "Hey, someone stole our cell wall!" gets from the cell periphery to the centrally-located nucleus. While Snap, Crackle, and Pop may be involved, it is more likely that communication is the result of interactions between various macromolecules. Dr. Peng's team is currently working to identify these macromolecules and describe how they interact with one another.




Targeting Tomatoes

Targeting Tomatoes

The most common garden vegetable is also a staple in research laboratories at Mississippi State. From herbicide tolerance to gene modification, tomatoes are being studied to help farmers grow the popular fruit with fewer losses or injuries to the plants. Dr. Sorina Popescu, assistant professor in biochemistry, molecular biology, entomology and plant pathology, is working to understand how tomato plants respond to pathogens at the molecular level, and editing the plants using CRISPR (clustered regularly interspaced short palindromic repeats) technology. Popescu explained that the technology allows her to silence a gene expression or make it louder, which affects the plant's response. The technique is promising, she said, because you don't bring anything new into the plant or take anything away.

"You only change what is already there," she said. "That's happening in nature anyway—plants evolve and become more sensitive because gene expression levels may go up or down. It is an alternative to genetically modifying plants."

The changes made using CRISPR technology do not fall under the current definition of genetically modified organisms. Popescu added, though, the jury is still out on how to label these altered foods. The pathogen Popescu is studying is called Pseudomonas syringae. It can easily wipe out an entire tomato crop if it infects the garden. Many labs across the U.S. and abroad are working with this pathogen because the losses from it are so significant, but also because it can be used to understand other similar pathogens. The pathogen causes brown-black leaf spots and specks on green and red fruit. The pathogen causes stunting and yield loss, particularly if young plants are infected. Most pathogens have effectors that act in very similar ways. Popescu believes the findings can be extended to other vegetable crops to make them less susceptible to pathogens.




Toxin-free castor would be major help to industry

Toxin-free castor would be major help to industry

Castor oil is the highly desirable, plentiful product of castor beans. The oil is used to produce everything from cosmetics and paints to jet aircraft lubricants and certain plastics. The thick oil makes up 60 percent of the seed's weight. By comparison, high-oil corn or canola only produce about 25 percent oil by weight. Ninety percent of the oil is ricinoleic acid, a fatty acid found in large quantities only in castor oil. This acid has many industrial applications.

MAFES scientist are trying to make it possible to grow the plant safely for commercial oil production in Mississippi. Castor seed meal, not the oil, contains ricin, a toxic protein that can become fatal if untreated in the body.

To make castor a commercially viable U.S. crop, scientists are trying to discover a way to genetically modify the plant so that either the gene that produces the toxin is no longer expressed or the toxin is no longer produced.

One of the challenges is that castor resists being transformed. The genetic modification process involves inserting a fragment of DNA foreign to the plant into the genetic code, where it must be accepted and become active.

Everything from cotton to corn and soybeans has been genetically modified, but castor is much more difficult. The castor cells can be transformed, but you can't get whole plants to grow from the cells.




Entomology

Ant study at Noxubee refuge suggests healthy ecosystem

Ant study at Noxubee refuge suggests healthy ecosystem

It is no secret that many ants live beneath the leaves, bark and soil of the Noxubee National Wildlife Refuge, but no one knew how diverse the population was until Mississippi State University entomologists dug up the facts.

Their findings show that imported fire ants and other exotics have not displaced the natives. More importantly, the distribution and diversity of ants at the refuge indicate a well managed, healthy ecosystem.

Scientists estimate that ants make up 10 percent of the terrestrial animal biomass on the planet. Ants are important to ecosystems because they decompose waste, aerate soil and bring in needed nutrients, disperse seeds, kill large numbers of other insects and are food for many animal species. Their distribution and diversity often indicate an ecosystem's ability to maintain itself.




High-protein insect studied at MSU

High-protein insect studied at MSU

Imagine an insect that can eat nearly anything, control microbes, live off of water alone in the adult stage, and be a good source of protein for animal feed. The black soldier fly is real, not science fiction, and it has researchers at Mississippi State University abuzz with excitement. MAFES scientists are studying the black soldier fly as a potential solution to dealing with large amounts of waste while also generating a feed product. Black soldier flies are 40 to 45 percent protein by dry weight. Theoretically, one metric ton can be produced per day in the space of a medium-sized house, and used as a feed product.

Harvested larvae can be dried and milled to create a high-protein meal for livestock, poultry and aquaculture consumption. Due to their high oil content, black soldier fly larvae may even be useful for biofuel production. They're not a known disease carrier, they don't bite or sting, and they're not a nuisance. They're a versatile species with huge potential.

Black soldier fly larvae will eat almost anything—manure, carcasses—without any remaining harmful fungi or microbial residue. These insects require no special diet, so they can be fed nearly any kind of agricultural byproducts or waste.




Identifying Destructive Invaders

Identifying Destructive Invaders

Exotic insect species enter the United States through multiple routes, such as on wood shipping pallets, plant materials, and imported fruits and vegetables. The U.S. government sets trade restrictions to help prevent the introduction of nonnative pests, and its inspectors work at all borders to search for and confiscate materials carrying these insects. Some hidden pests do make it past inspection and move into U.S. crops. Once established, these pests can damage crops and native plant species, ultimately causing severe economic damage. Quick identification of invasive species is crucial to stopping their spread. The Mississippi Entomological Museum was recently designated as the Eastern Region Identification Center for the USDA's Animal and Plant Health Inspection Service.




Invasive Beetle Threatens Avocados and Other Laurel Trees

Invasive Beetle Threatens Avocados and Other Laurel Trees

What is the power of a single insect? In the case of one invasive pest, it has the power to kill one third of the nation's laurel trees. The redbay ambrosia beetle carries a pathogen that causes laurel wilt disease. Dr. John Riggins, a forest entomologist with the Mississippi Agricultural and Forestry Experiment Station, is leading MSU efforts to battle the insect.

"This beetle is expanding its footprint in states where it has already been established," said Riggins, who is also a professor in the MSU Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology. "More than 145 counties in the U.S. are positive for the disease. It is such a perfect invader that it has proven so far to be impossible to stop its spread."

The redbay ambrosia beetle came to the U.S. from Asia in 2002 and was discovered in Mississippi in 2009. It has since been found from Georgia to Arkansas and southeast Texas. It threatens all members of the laurel family in the U.S., which includes sassafras, redbay, and commercially important avocados.

Efforts to control the pest are focused on educational campaigns. One message urges outdoor enthusiasts not to move firewood long distances, as a single female beetle introduced in a new region can reproduce and infect the entire area.

Researchers continue to look at ways to address the problem. Part of their effort is simply learning all there is to know about the insect, its habitat, and its life cycle. A recently published MSU study found that the beetle has a high cold tolerance and no native enemies, which means its spread will not be geographically limited to the South. In North America, sassafras is the most widespread tree species susceptible to laurel wilt.

"The natural range of sassafras trees is from coastal Mississippi to southern Canada," Riggins said. "We were hoping the cold winters might limit its spread, but it turns out that less than 1 percent of the geographic range of sassafras will receive protection from winter temperatures."

The next step in the research is to find resistant trees and plant them in the environment. Researchers at the University of Florida found resistant redbay trees, so there is probably resistance in some sassafras.




MSU Research Takes the Bite Out of Mosquitoes

MSU Research Takes the Bite Out of Mosquitoes

Since 1999, the United States has had 30,062 cases of West Nile virus, according to the Centers for Disease Control and Prevention. Of these cases, 1,247 were fatal. Mississippi has had 842 cases, including 48 fatalities.Like malaria, West Nile virus is spread by mosquitoes. West Nile virus and malaria cases together make mosquitoes the world's No. 1 vector for disease transmission. After Hurricane Katrina, coastal states became prime mosquito-breeding grounds, creating the possibility for a spike in West Nile cases and associated deaths.

The Mississippi Department of Health (MDH) held mosquito-education workshops throughout the state. The agency conducted pre- and postgrant surveys designed to gauge practices, knowledge and attitudes of local personnel in mosquito- control programs before and after disbursement of funds. Postdoctoral associate and veterinarian Kristine Edwards and associate Extension professor Jerome Goddard conducted research and workshops based on survey responses.

The study provided guidelines for cities to combat the disease-carrying pest. Steps include first surveying to find which ditches have mosquitoes, and then spraying larvicides to kill larvae in the standing water. The final tactic is spraying adulticides to kill mature mosquitoes.

The guidelines also recommend adult mosquito trapping, which captures seven to 10 mosquitoes on a typical night. When the count swells to 50 to 100 specimens, usually a week after a good rain, it is time to spray. Edwards said simple tactics like surveying and trapping can save local governments time and effort.




MSU researcher finds new grasshopper species

MSU researcher finds new grasshopper species
When JoVonn Hill stepped out of his vehicle in a cedar glade near Nashville, the first insect that crossed his path was a grasshopper never before identified. He gave the grasshopper the scientific name Melanoplus ingrami, honoring Wayne "Buddy" Ingram, an interpretive officer and naturalist at the Cedars of Lebanon State Park. Ingram has extensive knowledge of the area and was very helpful to Hill on several trips to the park.

Entomologists at MSU have been finding and naming new species for the last 100 years, and this includes several hundred species of beetles, moths, leafhoppers, wasps and other insects. JoVonn and four others currently on the staff of the Mississippi Entomological Museum have described and named about 20 new species in recent years.

Each species, from the smallest microbe to humans, plays an important role in maintaining biodiversity and keeping the earth healthy.




The Buzz Surrounding Neonics

The Buzz Surrounding Neonics

In the midSouth, early-season pest management is a significant challenge to farmers. For insects, relatively mild winters combined with long, productive growing seasons create an almost perfect environment for their propagation. It is not unusual to see a variety of pest species coexisting at high levels in many fields. Of specific concern to farmers are thrips, bean leaf beetle, three-corner alpha hoppers, and a variety of soil-dwelling insects. In addition to the challenges caused by insects, producers are migrating to earlier planting schedules in an effort to avoid late season drought conditions. The bad news is these earlier planting strategies make the crop more susceptible to soil insects. And increasing inputs to manage herbicide resistant weeds and decreasing commodity prices, force farmers to look at every aspect of their operation to remain profitable.

Neonicotinoids (also known as neonics) are systemic insecticides that are chemically similar to nicotine. The insecticide is absorbed by the plant and circulates through the plant's tissues, killing the insects that feed on them. Unlike contact insecticides, which remain on the surface of the treated foliage, systemic insecticides are taken up by the plant and transported to other plant tissues that may include leaves, flowers, roots, stems, pollen, and nectar depending on the method of application. Products containing neonicotinoids can be applied at the root level, as a seed coating, or sprayed onto crop foliage. The insecticide remains active in the plant for up to four weeks when used as a seed treatment or when applied to the root zone, extending the protection that neonicotinoids provide. In contrast, foliar applications may remain active for only a few days depending on plant size.

A decline in managed pollinators over the last decade led researchers to investigate if neonicotinoids were a contributing factor. Dr. Jeff Gore, associate extension and research professor of biochemistry, molecular biology, plant pathology and entomology at the MSU Delta Research and Extension Center, and colleagues at Mississippi State University, the University of Arkansas, and the University of Tennessee established collaborative research projects on the potential risks of neonicotinoids to managed pollinators. In addition to the neonicotinoid seed treatments, the entomologists looked at when and where pollinators are exposed to neonicotinoids.

Dr. Jeffrey Harris, assistant extension and research professor in biochemistry, molecular biology, plant pathology and entomology, noted that additional research was piloted to determine what would be the best time of day to spray insecticides to have the lowest impact on pollinators.

"The results showed that bees prefer the middle of the day for foraging. So if farmers and aerial applicators can spray later in the day, there would be less bee loss," Harris said. "Even better, if applications occurred in late afternoon, the insecticides would have ample time to break down before the next morning, which would be safer for honey bees."

The scientists concluded that the risk to pollinators from neonicotinoids is so small; there essentially is no risk in the Midsouth. The Delta environment in the Midsouth is one of the highest use areas for all insecticides on a yearly basis, but this area also has the highest honey production per hive based on the latest USDA estimates. It seems that this would not be the case if the relationships between insecticide use and honey bee decline were as clear as many reports imply.




Plant Pathology

Corn researchers develop in-field aflatoxin approach

Corn researchers develop in-field aflatoxin approach

MAFES scientists are researching new ways to reduce aflatoxin in infected corn. Corn is one of the state's leading row crops, but it is susceptible to aflatoxin, a fungus that can reduce profits and hurt marketability.

Aflatoxins are naturally occurring chemicals produced by the fungi Aspergillus flavus and A. parasiticus. The fungi appear as yellow-green or gray-green molds on corn in the field or in storage. Scientists are applying granules of Aspergillus flavus that do not produce aflatoxin but do compete with the native Aspergillus flavus. In essence, they are using a good fungus to fight a bad one. Aflatoxin levels are not normally high in corn, but Mississippi's hot, humid climate encourages the growth of the fungus that produces the toxin. Heat, drought, high humidity, insect infestation and anything else that stresses the crop favor fungal growth.

Aflatoxin can build up in crops such as corn, cotton, peanuts and tree nuts. Aspergillus infects corn by invading through corn silks or through insect damage to kernels or ears. Using non-aflatoxin-producing A. flavus strains has the potential to protect much of the state's corn harvest.




Cotton yields increase with new technology

Cotton yields increase with new technology

Researchers at Mississippi State University have developed technology that uses reflected light to analyze the presence of certain nematodes in cotton fields so producers can increase profits. Since 2001, MAFES and MSU scientists have been developing a way to use remote sensing technology to battle reniform and root-knot nematodes, which are the No. 1 cotton pest in Mississippi, Alabama and Louisiana. In recent years, Mississippi cotton producers lost more profits from these nematode infestations than any other state, including a loss of 225,000 bales worth $87.8 million in 2006.

Compared to the nematode counts, the data collected through hyperspectral imaging was 75 to 100 percent accurate. The data was used to generate a field map showing areas of low, medium and high nematode populations. From that, a prescription map for applying different amounts of nematicide was created. For the producers, the yields were higher, which increases profits. Plus they saved money by applying only the amount of chemical required rather than blanketing their field with the amount needed to treat the highest population of nematodes found in their soil samples. The third benefit is to the environment, because site-specific applications reduce the amount of chemical used.

This research benefits not only Mississippi, but the entire Southeast, as producers in Alabama and Georgia routinely use the site-specific application method for treating their fields.




MSU Leads the Charge Against Soybean Taproot Decline

MSU Leads the Charge Against Soybean Taproot Decline

Soybean taproot decline (TRD) has been compromising crop yields in the Southeast for more than a decade, but researchers have now identified the fungus that causes this disease. Mississippi Agricultural and Forestry Experiment Station (MAFES) scientists have been part of a cooperative regional effort to make the discovery. Plant pathologists Dr. Tom Allen, Dr. Maria Tomaso-Peterson, and Tessie Wilkerson spearheaded the effort along with scientists from Auburn University, the University of Arkansas, and Louisiana State University.

Allen said producers and allied agricultural professionals should scout for TRD throughout the growing season, but foliar symptoms consisting of interveinal chlorosis are most often observed in late summer, especially in August. "The interveinal chlorosis that is associated with TRD is more easily observed in the upper canopy since the rest of the leaves are green," Allen said. "Even though the symptoms associated with TRD can be commonly observed throughout the season, it is easier to observe the symptoms later in the growing season."

"We initially thought TRD could potentially be several different soybean diseases prior to when we were first able to document something that we considered to be new," Tomaso-Peterson said. Foliar symptoms associated with TRD look like many other root associated diseases, making it easy to confuse with others, Allen added.

Early sightings of TRD could have been misdiagnosed as sudden death syndrome, a disease that produces similar foliar symptoms.

The average amount of loss caused by the fungus is about 18 percent of harvestable yield. No fungicides are in development or currently labeled to control the disease. However, researchers are working to determine possible management tactics for TRD. Soybean research pathologists conducted field trials during 2016 at the Delta R&E Center to assess whether in-furrow fungicide applications and seed treatment products could help reduce losses associated with TRD.

"Possible strategies may include rotation, identification of the host range for this particular fungus, and screening commercially available fungicides to determine if anything currently on the market is efficacious against the fungus," Tomaso-Peterson said. "An integrated approach may serve best to reduce the potential yield losses associated with TRD."

"The hardest part about doing this kind of research is that farmers expect answers to a growing problem," Allen said. "Based on our observations over the past decade, it appears we have a long way to go to determine the proper management techniques for this particular disease to limit yield losses."




MSU research benefits poinsettia producers

MSU research benefits poinsettia producers

Researchers at Mississippi State University have found a cost-effective and environmentally friendly strategy for fighting one of the most serious soil-borne diseases in poinsettia production. Pythium stem and root rot is a common problem in poinsettia production because the fungus thrives in cool, saturated and poorly drained soils. MAFES researchers found a way to use organic methods and fewer fungicides to successfully fight this pathogen.

Pythium is a widespread fungus. Plants are cross-contaminated by splashing water or soil from pot to pot. In nursery management, producers treat the plants when they transplant cuttings to the pot. Once the disease is established, it is too late to treat, so growers have to use a fungicide early in the season to make sure they have a healthy crop. The standard conventional fungicide is effective but expensive, and there is a high risk that the fungus will become resistant to the chemical.

Managing resistance to important fungicides is a key component of a disease management program. One of the strategies MAFES scientists are researching is integrating biofungicides. Biological agents are not conventional fungicides or chemicals, but organic methods of fighting fungi or other harmful microorganisms. The study found that a reduced rate of the conventional fungicide, when used with a biological agent, resulted in plants that didn't rot and had similar growth to the label rate of conventional fungicides. This is beneficial to growers because it reduces their impact on the environment. It also reduces the risk of the pathogens adapting to the fungicides and becoming resistant and may save producers money by reducing the amount of fungicide they use.




New research to aid state's soybean growers

New research to aid state

Tiny soybean cyst nematodes cause big problems for soybean growers, but a Mississippi State University researcher is helping cut them down to size. The soybean cyst nematode, or SCN, is a small, plant-parasitic roundworm that attacks the roots of soybeans. Affected plants have stunted growth, wilt and often die. SCN has been a problem for Mississippi growers since the 1950s, and there is no known method of eliminating nematodes from the soil. Growers rely heavily on crop rotation and other farm management techniques to minimize damage. The dilemma has researchers interested in developing new soybean varieties.

It could be a few years before the new varieties developed will be fully tested and commercially available, but scientists are also working on other research that can assist farmers with current crop rotation techniques.

There are 16 types of SCN, commonly called "races." These races differ in their ability to reproduce on certain soybean varieties. Many fields have more than one SCN race in them. One race may be dominant with other minor races present. SCN can change races, depending on the available food sources. Therefore, growers must test their soil before planting in order to choose varieties that are not susceptible to the particular nematodes in their fields. Scientists have developed a new test that uses a gene marker technique that can identify nematode races in a molecular laboratory in a matter of hours.




Unlocking Mysteries

Unlocking Mysteries

In the world of turf science, mysterious brown spots provide a peek at the multitude of bacteria and fungi that live within our lawns. Dr. Maria Tomaso-Peterson, a research professor in biochemistry, molecular biology, plant pathology and entomology, recently classified Culvaria malina, a strain of fungus common in turfgrass, which had previously gone unclassified. While fungi identification might seem straight-forward, figuring out which fungus is causing a symptom can be difficult; every plant has a variety of fungi living on it and many are benign. In order to discover which is causing the problem, researchers isolate one fungus at a time.

"I try to think about it like a crime scene," said Tomaso-Peterson. "When I get a sample in, first I try to figure out which strains of fungi are supposed to be there, and which aren't. Then I slowly eliminate them one by one to figure out which one is linked to the symptoms."

In order to better understand the mystery fungus, Tomaso-Peterson set up greenhouse trials to examine which grasses were most susceptible.

"I found that zoysia and bermudagrasses were highly susceptible, which made sense, because those were the grasses I was seeing the fungus on most frequently," Tomaso-Peterson said. The fungus is easily recognized by the distinct black eye spot lesion it causes on the leaf itself. On turfgrass, it looks like a dark brown chocolate spot—golf course superintendents had nicknamed the disease 'inky spot.' "The fungus colonizes the infected leaf, so you can see the robust mycelium that covers it. That's what gives it the brown color. It wasn't something we had ever seen before. But as we started to look for it, we realized that it wasn't isolated to one region, but was all over the Gulf Coast," Tomaso-Peterson stated.

Conditions associated with the fungus are high rainfall and highly-maintained turf, like that on golf courses. By identifying the pathogen and then classifying fungi according to genus-species, scientists are able to create a body of work, recording data such as the conditions it is found under, the symptoms it causes, and the biology behind it. It also allows them to get an idea of how prevalent it is in plants within a region, and what steps might be taken to prevent plant diseases.