Investigating and developing FHB Resistance in Barley

The U of M barley breeding and genetics program is engaged in a comprehensive research effort to understand the genetics of resistance to FHB, develop technology to enhance breeding efforts to combat this disease, and release new varieties with improved levels of FHB resistance. This research effort is supported through federal, state and industry funded grants.

Research funded through the Minnesota Small Grains Initiative is specifically designed to complement the federal and industry grants.  The objectives outlined in the state proposal are twofold: 1) Developing strategies for DNA marker-assisted selection (MAS) for FHB resistance in the breeding program, and 2) Investigating the genetics of new sources of FHB resistance. 

In the first objective, we are developing strategies to use DNA markers in the laboratory to implement high throughput screening of barley breeding lines for FHB resistance. Our laboratory, in collaboration with Dr. Ruth Dill-Macky and Dr. Gary Muehlbauer, has described the genetics of resistance to two resistant sources thus far.  These sources, the varieties Chevron and Frederickson, are both poorly adapted to Minnesota and have poor malting quality, but do contain genes for resistance to FHB. 

Our research to date has revealed that it will be necessary to combine genes from multiple sources of resistance to achieve significantly better resistance in barley varieties. After identifying the locations of genes that confer resistance to FHB, we identify DNA markers that can be used routinely in the laboratory to screen large numbers of breeding lines to identify those that possess the desired genes.

We are currently using these markers to augment selection for Chevron-derived genes and will begin conducting selection with markers for genes from Frederickson this summer. By using these DNA markers to identify promising breeding lines, we should be able to more effectively select lines that combine resistance from several sources.

As DNA markers for resistance genes from new sources of resistance are identified, they can be added to our current set of markers and used to continue to build up levels of resistance. The first lines that were selected, in part, using DNA markers will enter preliminary yield trials this summer.

Our second objective in the Minnesota Small Grains Initiative is to conduct a genetic study of a new source of resistance.  This FHB resistant accession, called Hor211, is similar to Chevron and Frederickson in that it is poorly adapted to Minnesota and has little value as a malting variety.  However, studies we have conducted indicate that Hor211 likely contains different resistance genes than those we have already identified. 

We have evaluated a genetic mapping population created using Hor211 in several environments and are currently constructing a genetic map to identify DNA markers that will help us to select for resistance genes. 

Our federal grant is funding a similar study on another new resistant source called Atahualpa.  All four of these resistant sources (Chevron, Frederickson, Hor211, and Atahualpa) have been used in our breeding program. As we identify, test, and implement DNA markers that identify genes from these sources, we should be able to more effectively manipulate these genes and combine them into new breeding lines.  These breeding lines are eventually evaluated for yield, malting quality, and other important agronomic traits, and the most elite lines will become candidates for new barley varieties for the region.

–Kevin P. Smith, University of Minnesota barley breeder

Screening Germplasm for FHB
The Small Grains Pathology project, which includes Drs Ruth Dill-Macky and Brian Steffenson with the U of M Plant Pathology Department, continues to work in conjunction with the wheat and barley breeding programs to screen germplasm for reaction to FHB. 

To contribute to the screening effort, our project needs to work with Fusarium graminearum, the fungus that causes FHB.  Samples of infected wheat and barley and crop residue are collected each field season throughout the Red River Valley and Southern Minnesota.  From these samples, we are able to isolate the fungus and grow it in culture in our laboratory in St Paul.

By culturing F. graminearum from each of these plant samples we are able to make a collection representing the genetic diversity of the fungus in Minnesota. These fungal isolates are grown in the laboratory each spring to produce the spores, called macroconidia, that serve as inoculum in greenhouse studies and in field screening nurseries each growing season.

Our effort results in the production of approximately 400 liters of concentrated inoculum, which is stored frozen for later dilution and spray-application in field screening nurseries.  This inoculum has served the needs of a combination of as many as five Minnesota and federal research programs, and represents a substantial contribution to the FHB research efforts at the U of M.

A major focus of the research effort of this project is aimed at improving FHB screening techniques in the greenhouse plantings.  Greenhouse inoculations involve spray inoculations of barley and point-inoculation of both wheat and barley. These techniques are used to assess FHB disease severity and thus eliminate susceptible lines from the breeding program.

Screening data are also used in genetic studies of each of the breeding programs to identify resistance genes and conduct molecular mapping studies. We continually investigate other techniques that we hope will provide additional capabilities to the FHB screening effort. Our project also conducts research on the accumulation of deoxynivalenol (DON or vomitoxin) in wheat and barley.

Field plot inoculations are a collaborative effort of the breeding and pathology programs, which includes researchers at St Paul, Morris and Crookston. Approximately 4,000 rows of wheat were screened at Crookston and St. Paul station in the summer of 2002, with approximately equal numbers of plots at each location. Approximately 4,500 rows of barley were spray-inoculated at St. Paul, 1,400 rows at Morris and 4,000 rows at Crookston in 2002.

Over the past few years we have developed a dryland FHB screening technique that may prove useful to field screening efforts nationally and internationally. This technique for establishing a FHB screening nursery does not require the setup of a mist-irrigation system to promote disease development, and therefore does not limit screening nurseries to locations with a source of irrigation. Future expansion of the use of this dryland technique to screen a regional nursery of elite wheat germplasm is planned. 

– C. Kent Evans, FHB research associate, U of M Department of Plant Pathology

Mycotoxin Lab Instrumental in DON Analysis
The U of M Mycotoxin Lab, managed by Yanhong Dong, plays a critical role in analyzing mycotoxin data for FHB research to evaluate DON (deoxynivalenol, or vomitoxin), the toxic byproduct of FHB that can make wheat unsuitable for milling, and barley unsuitable for malting. In 2002, the lab analyzed an estimated 10,000 grain samples.  That compares with 5,518 samples in 1999/00 and 3,122 in 1998/99. The U of M lab is one of four in the country. Two other labs are at North Dakota State University, and another at Michigan State University.  All four labs are supported in part by the U.S. Wheat and Barley Scab Initiative. Quality assurance evaluation to ensure DON test accuracy indicates that the variation in analyses over several days is low and that there are no major differences in analytical values of check samples among the four DON diagnostic centers.

U of M mycotoxin lab manager Yanhong Dong with a new spectrometer in the lab used for grain quality analysis.

New Misting System at WCROC Morris
In 2002, the West Central Research and Outreach Center provided a screening site for preliminary yield, advanced yield, and uniform regional nurseries for the spring wheat breeding program of Dr. Jim Anderson, and a FHB misted nursery for the barley breeding program of Dr. Kevin Smith. WCROC also provided a screening site for a Roundup Ready spring wheat trial funded by Monsanto.

Morris has provided a misted FHB nursery screening site since 1995.  Dr. Smith provides us with lines from his FHB barley breeding program, and we grow the lines out for evaluation of FHB resistance. Last summer, we installed a new misting system replacing our old solid-set system with one with 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, creating conditions for optimum scab development.

– George Nelson, research scientist, NWROC, Morris