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University of Minnesota 2001 Scab Research Update The University of Minnesota Scab Research Initiative has been in place for about five years, getting underway in 1995 after Minnesota lawmakers first appropriated funding to boost scab research in 1994, following the severe 1993 epidemic that affected much of the Northern Plains. What has resulted since is an integrated, systematic focus on a specific research objective. Following are highlights of research on scab (also called Fusarium head blight, or FHB) at the University of Minnesota over the past year. FHB research at the U of M is augmented by the Minnesota wheat and barley checkoff programs, managed respectively by the Minnesota Wheat Research and Promotion Council, and the Minnesota Barley Council. ********************** Breeding Barley for Increased FHB Resistance The Minnesota Barley Breeding Program is enhancing its FHB resistance breeding effort by expanding traditional screening methods and evaluating new technology. This is made possible by the collaborative effort with Ruth Dill-Macky in the plant pathology department and the implementation of a DNA marker lab for the breeding program. The bulk of the barley screening is done in field nurseries located at St. Paul, Crookston and Morris. In 2000, the barley breeding and pathology programs screened over 1,500 new lines for FHB resistance representing a 25% increase over 1999. In 2001, the plan is to increase that number by another 25%. Kent Evans was hired last summer by the department of Plant Pathology, with the responsibility of managing the FHB screening nurseries in St. Paul and Morris. Galen Thompson has had the responsibility of managing the Crookston nursery for the past two years. These strong collaborative efforts make this large screening program possible. Last summer, the barley breeding program also initiated a new program to use DNA markers to enhance selection for FHB resistance. Our barley program, in collaboration with Gary Muehlbauer and Ruth Dill-Macky, has been working on identifying DNA markers associated with FHB resistance in barley for the past 5 years. We began a modest effort last year to test some of these new markers in the breeding program. We are hopeful that we will learn from these experiments and continue to find more markers that will allow us to take advantage of this technology in the future. – Dr. Kevin Smith, U of M barley breeder ************************ Breeding FHB Resistant Wheat We have two key objectives when it comes to FHB research here at the U of M: Our approach: Crosses are made between scab resistance sources and regionally adapted germplasm. Approximately 1,000 lines that are candidates for entry into preliminary yield trials are tested once for scab resistance under greenhouse conditions. Approximately 400 lines in preliminary and 150 lines in advanced yield trials are evaluated in greenhouse tests, and also in replicated field tests in Fusarium-inoculated nurseries at Crookston, St. Paul, and Morris each year. Improved resistance screening strategies are pursued, including the use of DNA markers to directly select for particular resistance genes. Year 2000 accomplishments/changes in the U of M wheat breeding program for FHB resistance: • Field and greenhouse screening has been increased during 2000/2001 to accommodate studies on the genetics of resistance to scab. Each year about 2,500 to 3,000 lines are screened for resistance to scab spread in the head in the greenhouse. More than twice the number of plants will be screened in the greenhouse in 2000/2001 compared to 1999/2000. • New DNA markers for scab resistance were discovered. These markers provide an alternative means to efficiently screen lines for their scab resistance. • Marker-assisted selection for scab resistance was initiated in 2000. Approximately 800 early generation breeding lines were screened for the presence of DNA markers associated with scab resistance. About 500 lines were found to contain the marker (and, therefore, the resistance gene). The 300 lines without the gene were discarded. By using the markers as an initial screening, we have a better chance of finding scab resistant lines in subsequent greenhouse and field testing. This work was facilitated by the purchase of a new DNA sequence analyzer last summer, and development of protocols to obtain DNA marker data from hundreds of plants in just a few days. The DNA sequence analyzer is shared by the wheat and barley breeding and genetics projects. • Three graduate students and one postdoctoral research associate, all working on the genetics of scab resistance and development of DNA markers, were added to the project in the past year. We anticipate future releases of varieties with improved scab resistance and good agronomic and grain quality traits, thus directly increasing grower profitability. Our project is also developing germplasm that can be used in other regional wheat breeding programs to breed for scab-resistant lines with adaptation to Minnesota. We also anticipate that screening methodology and techniques developed through this research will impact the efficiency of our project and others on a regional, national, and international basis. – Dr. Jim Anderson, U of M wheat breeder ************************ Record-Setting Mycotoxin Sampling In the 1999/2000 crop year, a record 5,500 grain samples were analyzed for mycotoxins by the Mytocoxin Laboratory in the University of Minnesota. More researchers are now using the toxin data for their scab research projects, primarily, to evaluate DON (deoxynivalenol, or vomitoxin), the toxic byproduct of FHB that can make wheat unsuitable for milling, and barley unsuitable for malting. An estimated 7,500 samples will be analyzed for mycotoxins in the 2000/2001 year, according to Dr. Weiping Xie, director of the U of M Mycotoxin Lab. ********************** Transgenic Wheat, Barley Plants Developed With Antifungal Genes The following is an update of the work in my lab as it relates to the U of M Scab Initiative: Wheat and Barley Transformation We are also testing the usefulness of a new promoter (Sugarcane Badnavirus promoter) sequence in wheat and barley. Promoters drive the expression of transgenes. We have inserted this promoter, attached to a reporter gene so we can track the activity of the promoter, into wheat and barley. Currently, we are examining the effectiveness of this promoter by following the reporter gene. Genomics Mapping – Dr. Gary Muehlbauer, U of M molecular geneticist ********************** Steffenson, Toubia-Rahme Boost U of M Plant Pathology Efforts Dr. Brian Steffenson and Dr. Hala Toubia-Rahme are two key personnel additions at the University of Minnesota, focusing on small grains research and outreach. Well-known in the U.S. malting barley research sector, Steffenson formerly headed up barley disease research at North Dakota State University. Among his responsibilities there, he managed barley germplasm and investigated FHB host resistance genes in barley. He will focus on barley disease research at the U of M as well, working in cooperation with other U of M faculty in St. Paul. One of his research projects at the U of M will be characterizing resistance types in barley. Toubia-Rahme is assistant professor of plant pathology, based at the Northwest Research and Outreach Center, Crookston. Originally from Lebanon, she received her BS Degree in biology there, and her MS and PhD in plant pathology at the National Polytechnic Institute in France. She was a visiting scientist at the Experimental Institute for Cereals in Italy, and has served as acting senior cereal pathologist responsible for cereal pathology in West Asia and North Africa, while with the International Center for Ag Research in the Dry Areas, Syria. She was a research associate in barley pathology at NDSU before joining the U of M faculty, where she will focus on small grains disease research and outreach. ********************* Effective Screening Nurseries Elite spring wheat and barley lines from breeding programs in MN, ND, SD, and Manitoba continue to be screened for FHB resistance at the Northwest Research and Outreach Center at Crookston. The screening nursery is inoculated with infected corn seed and misted to ensure adequate disease development. Ideally, screening nurseries would be grown at a number of sites throughout northwest MN. Multiple locations test whether a genotype that appears less susceptible at one location retains that same disease ranking at additional sites. We create multiple levels of FHB infection at one location, which is similar to developing misted, inoculated nurseries at multiple sites. Previously, (1995-1999) we have attempted to induce multiple levels of FHB infection by applying different amounts of inoculum. The approach used in 2000 involved applying a uniform amount of inoculum throughout the nursery, but the duration of the infection period was varied using fungicide and misting. Varying the duration of infection has provided useful information for characterizing genetic differences in FHB progression. The variety 2375 has been one of the less susceptible varieties available to growers for several years. However, when compared with other cultivars and advanced lines grown in the 2000 screening nursery, there appear to be elite lines being developed which are much less susceptible to kernel infection and DON accumulation (Fig 1 and 2). Note that the rate of disease progression and final amount is substantially less in more tolerant genotypes that are being developed. – Dr. John Wiersma, associate professor of agronomy; Galen Thompson, agronomy research fellow, Northwest Research and Outreach Center, Crookston. ******************** Crookston research areas dedicated to U of M wheat, barley breeders The 11th and 12th research ranges at the Northwest Research and Outreach Center at the University of Minnesota, Crookston, were dedicated to Donald Rasmusson and Robert Busch during the NWROC’s 2000 Field Day. Rasmusson, barley breeder at the U of M, and Busch, wheat geneticist and wheat breeder, are both retiring. Their successors are already in place: Jim Anderson has replaced Busch as wheat breeder, and Kevin Smith has replaced Rasmusson as barley breeder. Busch can be credited for the release of 11 wheat varieties during his 22 years with a joint appointment at the U of M and the USDA’s Agricultural Research Service. The most difficult moment of Busch’s career may be 1993, when the scab epidemic decimated wheat in the Northern Plains, prompting Busch to rebuild his wheat breeding program around a center focus—increased scab tolerance. His proudest moment may be the release of Marshall, a spring wheat variety which enjoyed great popularity among producers in the 1980s. Rasmusson first came to the U of M as associate professor in 1958, and became a full professor in 1966. He bred six-row barley varieties that became standards of the malting and brewing industry, including Robust, released in 1983. His last release will be Lacey, a new six-row malting barley variety intended to replace Robust as an industry standard. Research ranges at the NWROC are land areas where the experiment station conducts field plot research. The research range dedication honors those who have made genuine and long-lasting contributions to agricultural research in Minnesota. The last research range dedication was five years ago, when the Minnesota Association of Wheat Growers and the Minnesota Wheat Research and Promotion Council were honored. Other honorees during the NWROC’s 105-year history are Henry Borgman, Carl Ash, Raymond Dunham, Olaf Soine, Robert Robinson, Jean W. Lambert, Elmer R. Ausemus, B.E. Youngquist, and Richard Behrens. ********************* Improved FHB Screening, Evaluation Techniques Research in the U of M small grains pathology program continues to focus on screening for resistance to FHB, in cooperation with the wheat and barley breeding programs. This effort involves the oversight of inoculum preparation during the winters, and spray applications of inoculum within screening nurseries of the respective breeding program during the summer field season. A large effort is maintained each field season assessing FHB reactions within plots at the three screening locations of St. Paul, Morris, and Crookston. Approximately 5,000 wheat rows and 2,200 barley rows were screened in the 2000 St. Paul nurseries. Much of this material was screened at Morris and Crookston as well. This effort will continue and perhaps increase in size during the 2001 screening season. Currently, all of the wheat and barley screening nurseries are conducted under mist-irrigation at the three locations. The mist-irrigation provides uniform moisture for standardized infection of FHB. Creating the optimal level of disease under mist-irrigation has been difficult at times. Therefore, we have sought alternative screening techniques to reduce FHB levels and improve the breeder’s ability to differentiate resistant from susceptible breeding lines. We have found that we can spray inoculate plots without mist-irrigation and still establish uniform FHB infections. This results in FHB levels that are lower but more like the FHB levels that growers experience in their field situations. The most striking advantage is that we can differentiate among resistant and susceptible check cultivars in the non-misted plots for both wheat and barley as good as or better than in mist-irrigated plots in the same experiment. At present, we do not know if this strategy will provide useful information during a drier year, but the results are very encouraging and suggest that our screening efforts may not be limited to mist-irrigated locations. In the 2001 screening season, we plan to conduct screening nurseries in locations without mist-irrigation in an effort to provide the breeders with a comparison of elite material under high and low disease levels. Our research in barley suggests that resistance to DON accumulation may be separate from resistance to FHB severity. We observed a trend where resistant barley tended to have higher toxin accumulation 72 hours after infection on a per-kernel basis when compared to FHB susceptible barley. This could mean that resistant barley has fewer infected kernels but these may have a higher toxin level. The study was conducted on a limited number of barley lines and additional research is underway in cooperation with the barley breeding program to determine if this trend exists for other breeding material. We have also developed a method to produce spores of Fusarium graminearum that have no detectable toxins in them. This inoculum is suitable for studies on toxin production, since the inoculum does not introduce toxin at the time of inoculation. This will enable researchers to study toxin production early in FHB infections, and may be useful in understanding the relationship of the toxin with disease responses in the host plant. – Dr. Conrad Kent Evans, FHB research associate, U of M Department of Plant Pathology *********************** Storage of Scab-Infected Grain Previous U of M research on the storability of grain infected by FHB, and supported by the state’s FHB Initiative, indicated that infected grain deteriorated slightly faster in storage than did grain that had been cleaned on a gravity table to remove scab-infected kernels. However, the differences in storability between cleaned and uncleaned grain were relatively small. This means that instead of selling scab-infected grain at a low price during harvest, careful grain managers can store the crop and wait for better marketing opportunities. There was so much sample to sample variability in DON measurements taken during the study on storage of scab-infected wheat that no conclusions could be drawn about changes in DON during storage. The fungus species that causes scab infection and produces DON remained viable during storage at 18% and 20% moisture, but that fungus species died during storage at 16% moisture. This means that DON production during storage is unlikely for wheat stored at less than 16% moisture. ********************** Pathogen Development and Pathogenesis in FHB Our objectives are to understand how the head blight fungus Fusarium graminearum, enters and spreads in tissues of wheat and barley spikes and how it causes damage there. Toward these goals, we have used microscope techniques to follow fungus development both in spike tissues and in tissues of detached leaves. This year, we have located the sites most likely to be pathways of fungal entry in barley spikelets, including stomates and crevices between the glumes (the palea and lemma) of each floret. We also found that the interior surfaces of the palea and lemma have thin-walled cells, which may be vulnerable to fungal penetration. In the detached leaves, we confirmed that the invading head blight fungus initially grows between cells for a day or two without doing much damage before cells begin to die as the fungus penetrates to grow inside cells. The work has given us the methods and experience needed to learn how the fungus enters and damages heads of wheat and barley. – W.R. Bushnell , ARS-USDA Cereal Disease Laboratory, St. Paul MN
(The USDA-ARS Cereal Disease Lab located at the U of M’s St. Paul campus complements scab research conducted under the Minnesota Scab Initiative. More information about CDL research may be found on the web: www.cdl.umn.edu). ************************ Wiersma Plays Key Role In Outreach Effort Outreach information has been instrumental in helping producers manage FHB, and playing a key role in this effort is Dr. Jochum Wiersma, small grains specialist based at the NWROC, Crookston. Wiersma works with extension educators in the region to disseminate information, conducts on-farm cropping trials, and most recently, helped coordinate production of “The Minnesota Small Grains Production Field Guide.” With nearly 200 pages and about 90 color photos, 10,000 copies of this pocket-sized, spiral bound book were distributed to grain growers throughout Minnesota and made available online, at www. smallgrains.org ********************* Developing a Decision Aid for Optimizing Chemical Management of FHB Dr. Roger Jones, U of M extension plant pathologist, has been collaborating with commercial crop consulting and chemical companies to evaluate semi-quantitative PCR (polymerase chain reaction) head sampling as a decision-aid tool for improving the profitability of fungicide applications using producer-collected grain samples. To successfully integrate fungicide treatments for FHB with current management practices, quantitative PCR methods for estimating scab inoculum have been tested, and a sampling protocol has been developed involving private crop consultants. Last year, Jones’ PCR testing was expanded to include analysis of Septoria. In addition, Jones was among 15 plant pathologists across the nation in 2000 to participate in field research to analyze the effectiveness of commercial and experimental fungicides to suppress scab in wheat and barley. The researchers are also studying how different application methods may influence the effectiveness of fungicide applications. The research has helped support the registration of some commercial fungicide products, and helped producers make better fungicide application decisions. ************************* Fusarium Head Blight (Scab) Research Initiative 2000-01 Biennium Breakdown of Major Projects, Funding, Principle Contacts Development Of Disease-Resistant Wheat Varieties Development of Disease-Resistant Barley Varieties Molecular Approaches of Genetic Resistance to FHB in Wheat and Barley Biology, Epidemiology, and Management of Scab Mycotoxin Detection and Analysis FHB Resistance in Spring Wheat and Barley: Effective Screening Nurseries Residue Management and Inoculum Potential of Fusarium Scab Research at West Central Research and Outreach Center, Morris Scabby Wheat Assessment Using Machine Vision and Neural Networks Coordination and Communication TOTAL: $1.65 million For more complete research project information or budget details, contact FHB Coordinator Frank Pfleger ************************ Other Contacts: Kurt Leonard, USDA Cereal Disease Lab Jochum Wiersma, U of M Small Grains Specialist Phil Larsen, Vice President & Dean COAFES Tom Anderson, Chair, Small Grain Research and Education Committee Minnesota Barley Research and Promotion Council Minnesota Wheat Research and Promotion Council More comprehensive scab research information may be found in the booklet, “2000 Wheat Research Review.” It is free to the public and may be requested by contacting the Minnesota Wheat Research and Promotion Council, 1-800-242-6118. More scab research information is also available on the World Wide Web, at the MWRPC web site, www.smallgrains.org, and the University of Minnesota Agricultural Experiment Station, www.maes.umn.edu. Research conducted at the U of M and other research institutions under the U.S. Wheat and Barley Scab Initiative can be found on the Internet at: www.scabusa.org. This report prepared in cooperation by the University of Minnesota and the Minnesota Wheat Research and Promotion Council. |
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