|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
 |
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
University of Minnesota 2002 FHB Research Update The University of Minnesota Scab Research Initiative got underway in 1995 after Minnesota lawmakers first appropriated funding to advance research of Fusarium Head Blight (FHB, scab) in 1994, following the severe 1993 epidemic that affected much of the Northern Plains. What has resulted since is an integrated, systematic focus to find multi-faceted solutions to manage FHB in wheat and barley. On the following pages are highlights of FHB research at the University of Minnesota and the USDA-ARS Cereal Disease Lab over the past year. This research is augmented by Minnesota wheat and barley growers through their checkoff programs, managed respectively by the Minnesota Wheat Research and Promotion Council, and the Minnesota Barley Council.
Accelerated breeding of FHB resistant wheat Last year, a total of 5,686 plots containing breeding material and FHB resistance sources (excludes mapping populations) were screened in inoculated, misted field FHB nurseries in Crookston, Morris, and St. Paul. These evaluations included 189 lines in advanced yield trials and 382 lines in preliminary yield trials. Five experimental lines were entered into the 2001 Uniform Regional Scab Nursery. These lines were identified in 1999 and 2000 as having improved levels of FHB resistance. Nine hundred ninety three breeding lines were screened during 2000/2001 in the greenhouse for reaction to FHB inoculation. Marker-assisted selection was used to screen approximately 500 F4 (elite) lines during the summer of 2001. One hard red spring wheat line, MN95002, was approved for preliminary seed increase in 2001. This line has high grain yield, test weight, and grain protein and is moderately resistant to FHB, similar to the variety 2375. In the last several years, based on FHB field screening data of 14 spring wheat cultivars evaluated in 10 Minnesota nurseries, the U of M has established more effective and efficient ways to test lines for FHB resistance. The data showed that for initial evaluations, susceptible material could be reliably identified and discarded based on data from two replicates in three environments, and advanced generation material requires five to seven environments of replicated testing to accurately assess FHB reaction. We have identified more than 10 additional DNA markers evidently located in the chromosome 3BS region previously discovered to contain a major FHB resistance gene. These new markers are useful as selective agents for the resistance gene and future mapping.— James Anderson, U of M wheat breeder New Wheat Geneticist Focusing on FHB Research Effort As a wheat geneticist, Garvin will focus his efforts on studying the type, number and location of genes that code for desirable and undesirable genes that exist within the plant. This information can then assist the wheat breeder in developing new varieties that possess desirable characteristics, but lack undesirable ones. Having two scientists focusing on these objectives, rather than one, will result in broader coverage of research issues in wheat improvement, he says. Garvin received his masters degree in plant science at the University of California-Riverside, and his Ph.D. in plant breeding at Cornell University. Before coming to St. Paul, Garvin was a research molecular biologist with the USDA-ARS at Cornell University, where he conducted research on modifying the nutritional properties of crops, and on improving tolerance of small grains to soil stress factors. Working in cooperation with U of M crop scientists, Garvin's research will focus in large part on genetic and molecular aspects of FHB resistance in wheat. “In addition to characterizing existing FHB resistance genes, we are also interested in the possibility that there may be genes in wheat that suppress the action of known FHB resistance genes. If so, this may provide new avenues for enhancing FHB resistance in wheat that complement ongoing research by others,” he says.
Investigating and developing FHB Resistance in Barley The federal funding has supported traditional breeding efforts and research to map the positions of genes that provide resistance to FHB. Our funding from the state initiative is directed towards enhancing molecular marker tools for basic genetic research and marker assisted breeding and to study the genetics of new sources of FHB resistance. In addition, our breeding program collaborates with Dr. Ruth Dill-Macky in the department of Plant pathology to screen for resistance to FHB in the field and greenhouse and that research is supported by the state initiative. The first objective of our state grant is to enhance genetic maps with more useful DNA markers. We currently have molecular marker maps for five genetic populations. Each of these maps were developed independently and at different times using different markers. This makes direct comparisons among the different studies difficult. In addition, the type of the marker commonly used for these studies is quite laborious to perform in the laboratory and not well suited for use in high throughput screening in a breeding program. Thus, we have focussed on using a relatively new type of marker, simple sequence repeat (SSR) markers, to enhance the maps we have available. These markers are well suited for application in a breeding program. In the past year, we have added approximately 52 SSR markers to maps we have developed in our laboratory. New laboratory space made available by a remodeling project in Hayes Hall in the department of Agronomy and Plant Genetics has greatly helped this effort. The lab, finished this past fall, is 2300 sq. ft in size, houses 18 graduate students and scientists, and is primarily used by the wheat and barley breeding and genetics programs. The second objective of our state grant is to map genes for FHB resistance from a new source of resistance. It is clear from our research on resistance to FHB in barley that multiple genes from multiple sources of resistance will be necessary to attain levels of resistance that are needed to make barley production profitable. To reach that goal, we intend to map with DNA markers as many genes as we can identify and use these markers to accumulate these genes in superior malting barley lines. This past year, we have constructed a new mapping population consisting of 243 lines. We have begun to screen markers that will be placed on this map and will begin field evaluations of the population in the summer of 2002. This overall effort to improve molecular marker tools should help us to enhance our traditional breeding effort by combining multiple resistance genes to provide higher levels of FHB resistance in barley.—Kevin Smith, U of M barley breeder
Effect of Rate, Timing, And Frequency of Application in Controlling FHB Optimum growth stage for both fungicides for controlling FHB and improving the yield and quality parameters was at full head emergence in barley (Feekes 10.5) and at kernel developing and watery ripe in wheat (Feekes 10.54). In general, no significant effect of the reduced rate was obtained. The recommended rate was as efficient as the higher rate or multiple applications in reducing FHB severity and improving the yield and quality parameters of both barley and wheat. – Hala Toubia-Rahme, U of M extension small grains pathologist, Crookston.
Characterization of FHB Resistance in Barley Barley breeders can only accommodate three to five resistance sources in their FHB program. To effectively identify and exploit the very best sources of FHB resistance for breeding, controlled greenhouse evaluations are being made on the 10 barley accessions selected for resistance in the field. These selected accessions will be analyzed for resistance type (i.e. resistance to initial infection and to spread), pathogen growth and DON accumulation. Pyramiding genes from the most resistant accessions will facilitate development of malting barley cultivars that yield well and accumulate low DON levels under FHB epidemics. – Brian Steffenson, U of M plant pathologist, St. Paul Table 1. FHB severity (%) and DON concentration (ppm) of the 10 most resistant six-rowed barley accessions identified in the field at St. Paul, 2001.
2Not tested.
Carson New CDL Research Leader Dr. Martin Carson recently accepted the position of research leader at the USDA-ARS Cereal Disease Laboratory. He replaces Kurt Leonard, who retired. Carson will join the CDL February 11, 2002. In addition to administrating and coordinating CDL research activities., he will carry out his own research projects, including FHB. Carson received a Ph.D. in plant pathology from the University of Illinois, then served for nearly 10 years as a plant pathologist at South Dakota State University. Since 1989, he was supervisory research plant pathologist in the USDA-ARS Plant Science Research Unit at North Carolina State University.
Dryland FHB Screening Proving Helpful in Emulating Farm Field Conditions In the field in 2001, the collaborative efforts of the wheat and barley breeding, the pathology program, and station collaborators inoculated and assessed FHB in 8,575 rows of wheat and 10,514 rows of barley. The Small Grains Pathology field research consisted of 1,256 rows of material in various experiments. This material was planted at the St. Paul, Morris, and Crookston locations. Most of the wheat and barley screening nurseries are conducted under mist-irrigation at the three locations. Mist irrigation promotes the development of FHB ensuring that breeding lines are challenged with the pathogen. The success of these efforts relies on a close collaboration with station personnel at the Morris and Crookston Research and Outreach Centers. Corn seed inoculum is used at Crookston, and the station personnel there provide the expertise and management to facilitate successful screening at that location. The mist-irrigation at each location provides uniform moisture for standardized infection of FHB. During the winter months we inoculate and assess as many as 4,000 pots of wheat and barley from the respective breeding programs to screen promising material for resistance to FHB. In the summer of 2001 we concluded a two-year study involving the management of mist-irrigation volume to establish the optimal level of FHB in screening nurseries. We also completed a three-year study aimed at evaluating different inoculum concentrations and the level of FHB developed in a wheat screening nursery. The data from the two studies allow us to better manage screening nurseries and avoid creating too much disease. FHB levels that are too high obscure our ability to distinguish between resistant and susceptible reactions of wheat and barley. From these studies, we found that we can spray inoculate plots without mist-irrigation and still establish FHB infections. While inoculating plots at sites away from irrigation frequently results in FHB levels that are lower than mist-irrigated nurseries, we do generate FHB levels similar to those that growers experience in their own fields. The most striking advantage is that we can differentiate among resistant and susceptible check cultivars in non-misted plots for both wheat and barley. Dryland screening of barley at Crookston, in collaboration with the barley breeding program, was conducted in 2001. The data obtained were useful and will provide additional information to the breeding program regarding the reaction of their experimental lines to FHB. In the 2002 screening season, we plan to conduct dryland screening in populations of wheat we have developed to evaluate the utility of earlier generation inoculations to improve the efficiency of FHB screening. Previously we reported that resistance to deoxynivalenol (DON or vomitoxin) accumulation may be separate from resistance to FHB severity. We have observed a trend where resistant barley varieties have tended to have higher toxin accumulation 72 hours after infection on a per-kernel basis when compared to FHB susceptible barley. The original study was conducted on a limited number of barley lines and additional research is underway in cooperation with the breeding program using additional barley lines. The barley breeding program is trying to identify genetic markers associated with either high or low DON accumulation. We are in the process of conducting disease screenings under greenhouse conditions and analyses of DON accumulation on a much larger set of barley germplasm. The breeding program then utilizes this data in conjunction with their genetic analyses to identify the genes providing resistance to DON accumulation. – C. Kent Evans, FHB research associate, U of M Department of Plant Pathology
Decomposition of Residues that Support Overwintering Fusarium graminearum Wheat, barley, and corn were grown in the 2000 growing season in side-by-side strips. The crops were harvested with a commercial combine and the residue was distributed over the plot area through the straw chopper on the combine. Two large whole plots in each of four replications were established in each residue type. Residue was left as is in one plot and as much residue as possible was removed from the other plot using a plot forage harvester and hand raking. Each plot was then divided into seven subplots and randomly assigned to N fertilizer rates. In 2001, all plots were planted to sugarbeets, which was to be used as a plant N availability monitor. Soil core samples were then obtained. Wheat residue recovered from the soil cores declined during the growing season indicating decomposition. There was substantial variability in the amount of residue recovered, but generally more residue was recovered from cores taken from areas where previous crop residue was left compared to where it was removed. By August, this was still generally the case, but the difference was considerably less. Differences in recoverable residue between the two sampling dates (May and August) indicate that 50% of the residue decomposed where residue was left, compared to 33% where residue was removed. Keep in mind, that when residue was removed, some residue on the soil surface was left (was not picked up with the hand rakes) as well as the stubble (< 2 inches). The data would indicate that the residue we were able to remove was also the more readily decomposable residue as indicated by the greater percentage of decomposition when the residue was left as is. Dr. Ruth Dill-Macky recovered residue lying on the soil surface from each residue type area. This was done in the 2001 experiment where the residue was produced the previous year. It was also done in an area where the residue was produced in 1999. This would allow comparisons of residue that was one or two years old. These samples were to be evaluated for viable Fusarium graminearum growth. This experiment will be repeated in 2002, but on a site with low residual soil N levels. Wheat, barley, and corn crops were grown, harvested, and residue removed from selected whole plots in the fall of 2001. Sugarbeets will be used again as the N monitoring crop in 2002 because of its sensitivity to soil N availability early and late in the growing season. –Albert Sims, U of M soils scientist, Crookston.
On-Farm Trials and Outreach Although not funded directly by the state initiative, I started a three-year project in 2001 to evaluate the effectiveness of different fungicide management strategies in hard red spring wheat in cooperation with Bayer North America, Inc. and the U.S. Wheat and Barley Scab Initiative. I hope to answer questions related to whether or not to use fungicides given the level of genetic resistance in a particular variety. Initial results of the fungicide management look promising. – Jochum Wiersma, U of M extension small grains specialist, Crookston
Effect of Burning Wheat and Barley Residues on Survival of Fusarium Two wheat fields at the NWROC in Crookston were used in this study. In September, 2000, five quadrants were burned in each field. Five additional non-burned quadrants were used as controls. Residues left after burning and all residues in control plots were collected and stored at 14 degrees F. until later analysis. To quantify the effect of burning on residue, the total number of nodes recovered was determined for each experimental plot. There was a significant reduction of nodes recovered from burned (Field A, 531; Field B, 395) than from non-burned treatments (Field A, 1,680; Field B, 1,117). Isolations made on culture media showed that nodes recovered, irrespective of treatment, were readily colonized by F. graminearum and C. sativum. Recovery of F. graminearum from wheat residues was significantly reduced in burned nodes in comparison with non-burned nodes. Similarly, burning also reduced the recovery of C. sativus. Recovery of F. graminearum and C. sativus was almost nil from residues appearing to be totally charred. Burning reduced the amount of residue left on the soil after harvest by two thirds, and substantially reduced the population of F. graminearum and C. sativus present in straw. These findings implicate that straw disposal may provide an additional control option for these residue-borne diseases. A judicious residue burning in which residues are not totally destroyed may assist in the management of destructive diseases such as FHB, while still meeting soil conservation objectives. – Ruth Dill-Macky, U of M plant pathologist, St. Paul
Mycotoxin Lab Instrumental in DON Analysis
Effect Of Commercial And Experimental Fungicides In Controlling FHB The treatments were applied at early flowering (Feekes 10.51) for wheat, and at early full head emergence (Feekes 10.5) for barley. Artificial inoculation of Fusarium graminearum, in the form of infected corn kernels were added to the plots. Treatments were applied at 40 psi in 20 gpa; using hand-boom sprayers equipped with XR8001 flat fan nozzles angled forward/backward at 30° from horizontal. Fusarium head blight incidence and severity and leaf disease severities was assessed at soft dough stage of kernel development. Plots were harvested for yield and quality measurements, and DON concentrations were determined. Fusarium damaged kernel percentages was determined on the harvested samples. Treatment results with Stander: Treatment results with Ivan:
Investigating How FHB Infects the Heads of Wheat and Barley Plants Therefore, we are trying to find out how the fungus gains access to the floret interior. The principal postulated pathways of entry into florets are: 1) stomatal openings on the exterior surfaces of florets; 2) crevices between the lemma and palea, the two overlapping structures that enclose the floret; and 3) the mouth at the apex of the floret. In 2001, we evaluated each of these pathways. Results suggest that stomates are not a major pathway of entry, at least not the stomates on the lemma and palea of the barley floret. Our research confirmed that the lemma-palea crevice as a pathway of entry and highlighted the importance of the palea as a site of initial colonization. Further, that the mouth at the floret apex provides an avenue for fungal growth into the interior of the floret. Overall, the results demonstrate the ability of the FHB pathogen to colonize floret surfaces under field conditions. Preliminary results also suggest that the fungus may be obtaining nutrients from floret surfaces which promote fungal growth. In 2002, we will follow up investigation of floret invasion with both laboratory and field experiments to confirm the results reported here. In addition, we will investigate fungal penetration of thin-walled epidermal cells in the floret interior. This research was done in conjunction with an investigation (funded by the U.S. Wheat and Barley Scab Initiative) of the effects of DON in the development of FHB, and the physiological response of a wheat or barley plant to infection. We found that DON induces rapid and complete loss of chlorophyll and carotenoid pigments in detached barley leaf segments. This bleaching response is light dependent and not closely associated with leaf cell death. In addition, at low concentrations, DON induced reddish-brown pigmentation in leaf segments. These results indicate that some of the bleaching and browning in spikes typical of FHB may be a direct effect of DON. – W.R. Bushnell ARS- USDA Cereal Disease Laboratory, St. Paul
Screening for FHB at NWROC-Crookston A telephone line and modem were installed on the weather station located in the center of the nursery area last year. This allows display of nearly real time weather information on the NWROC web page at http://nwroc.umn.edu/weather/weather.htm. Historical weather information is also collected on the same web page and development of a database is continuing to allow recovery of weather records spanning any desired timeframe. A sprayer was built last summer to allow pesticide application without interfering with the misting system. Topographical mapping of the 40 acres used for misted nurseries was also completed with the help of a Moorhead company. This mapping helps give a much clearer understanding of drainage patterns in the field and what actions could be taken to improve drainage. The mapping also provides a starting point for tracking and positioning other observations since the map is geo-referenced. Areas of poor growth in the nursery section used last summer were located with GPS and added to the map. Temperature, relative humidity and leaf wetness was monitored in two nursery locations. FHB development was adequate for screening analysis, although onset of visual symptoms developed well after heading, resulting in a very short time frame between scoring for FHB and plant maturity. Daytime relative humidity appears very similar when comparing 2001 to 2000. However, when comparing daily low temperatures, 2001 appears cooler than 2000 from about June 30 to July 5. Possibly, the return to warmer temperatures around July 5, 2001 affected the rapidity with which visual symptoms appeared. Environmental conditions for FHB development were apparently favorable following July 6, because the 850 row dryland barley experiment, which was spray inoculated with spores on July 6 and 9, developed adequate FHB visual symptoms to allow scoring. – John Wiersma, associate professor of agronomy; Galen Thompson, agronomy research fellow, Northwest Research and Outreach Center, Crookston.
Rapid Antifungal Protein Gene Pretesting We are using a microassay approach or a faster method to test antifungal protein genes (AFP’s) that are of potential value in genetic engineering of cereals for resistance to FHB. Currently it is very expensive and time-consuming to screen AFPs of unknown efficacy using whole-plant transformation and adult plant disease testing. Thus, Pretesting AFPs makes it possible to speed development of FHB resistant wheat and barley. Glasshouse testing for FHB resistance of material in this study was begun in 2001 and results should be complete in 2002. – Richard Zeyen, U of M Professor of Plant Pathology
FHB Research at WCROC-Morris Since 1995, Morris, located in the southern end of the wheat/barley growing area, has provided a misted nursery screening site for the U of M wheat and barley breeding programs. Dr. Anderson and Dr. Smith provide us with lines from their FHB breeding programs, and we grow the lines out for evaluation of FHB resistance. Last spring, we replaced our old misting system with a new system that has flexible tubing and lower water pressure requirements. This allowed us to reduce the spacing between misting nozzles from 18 feet to 12 feet, providing more thorough and uniform wetting of the plants. A non-misted wheat/barley inoculation timing study, under the direction of Dr. Kent Evans, was also located in Morris in 2001. – George Nelson, research scientist, NWROC, Morris.
Minnesota Fusarium Head Blight (Scab) Research Initiative 2002-2003 Biennium Breakdown of Major Projects, Funding, Principle Contacts Accelerated Breeding of Fusarium Head Blight Resistant Wheat Pathways of Entry by Fusarium Head Blight Expression of Resistance to Fusarium Head Blight in Wheat Screening Systems for Resistance to Fusarium Head Blight Developing a Decision-Aid for Optimizing Chemical Management of Fusarium Head Blight Enhancement of Scab Resistance in Wheat and Barley by Molecular Genetics Fusarium Head Blight Nursery – West Central Research & Outreach Center-Morris General Wheat Support – West Central Research & Outreach Center – Morris Coordinator Budget Investigating and Exploiting Resistance to Fusarium Head Blight in Barley Characterization of Fusarium Head Blight Resistance in Barley Fusarium Head Blight Resistance in Spring Wheat and Barley: Effective Screening Nurseries Support for new Small Grains Plant Pathologist Position – Northwest Research & Outreach Center - Crookston General Support of Small Grains Specialist –Northwest Research & Outreach Center - Crookston Red River on Farm Trials for Spring Wheat and Barley – Northwest Research & Outreach Center - Crookston General Support of Wheat Research Programs-Northwest Research & Outreach Center Mycotoxin Analysis Services for Fusarium Head Blight Resistance TOTAL: $1,623,002
Other Contacts: Tom Anderson, Chair, Small Grain Research and Education Committee, ph. 218-354-7556 farmandy1@aol.com Minnesota Barley Research and Promotion Council, Marvin Zutz, Executive Director, ph. 218-253-4311 mzutz@gvtel.com Minnesota Wheat Research and Promotion Council, David Torgerson, Executive Director, ph. 218-253-4311 torgerso@gvtel.com More comprehensive scab research information may be found in the booklet, “2001 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. Photos: Tracy Sayler; Dave Hansen, Minnesota Agricultural Experiment Station, |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||