Breeding versus Mapping Resistance to Fusarium Head Blight in Barley

Disease resistance research at the University of Minnesota Barley Breeding program is funding through the Minnesota Small Grains Initiative as well as industry and federal grant programs. Our work on Fusarium head blight (FHB) is leveraged with the USDA-CSRESS funded Coordinated Agriculture Project (CAP) (see article in Issue 91 of Prairie Grains). In this project, the goal is to use a novel approach to mapping the location of disease resistance genes that will prove more useful in breeding.

Until recently, the two research activities of breeding and genetic mapping have been conducted as separate enterprises. Genetic mapping studies use specialized populations whose purpose is solely to map the locations of genes. Once these gene locations are known, breeders can then use genetic markers that are close to the gene to identify breeding lines that carry the gene of interest.  This is referred to as marker assisted selection or MAS.  While this approach has been successful in some cases, it has several drawbacks. It takes five to seven years to develop a mapping population, collect all the disease data for that population, and build the genetic map. Also, sometimes the effects of genes when measured in the genetic mapping studies don’t match the effects that are observed when these genes are in breeding lines.  For these and other reasons, the discoveries in mapping studies have been slow to be utilized in plant breeding. Therefore, a major dilemma in breeding programs is deciding how much resources to devote to mapping versus breeding.

The Barley CAP was designed to bridge the gap between breeding and genetics research activities.  This project takes advantage of recent molecular technology for mapping and utilizes data that is routinely collected in breeding programs to identify markers that can be used for MAS. In our Small Grains Initiative project, we are collecting FHB data from 384 breeding lines from four Midwest breeding programs in each of four years.  Each of these breeding lines is genotyped with a set of 3,000 genetic markers that cover the entire barley genome. This very large data set will allow us to map genes in our breeding lines and use this information for MAS immediately. We are now just beginning the third year of this project.  Graduate student, Jon Massman, has begun to analyze the data collected from the first two years.  Over the next few months, he will be identifying markers that we can use for MAS.

In our breeding program, we typically screen with markers on plants that are grown in the fall in a greenhouse. This is also the time when we make new crosses between different parents. Markers we identify from this project will be used this fall to examine parents for new crosses and for populations in our breeding program that are already in development. Breeding lines identified with these markers will start showing up in our yield trials in the next two years.  In this way we hope to combine our mapping and breeding efforts to more quickly develop new varieties with enhanced FHB resistance.

-- Kevin P. Smith, Associate Professor, U of M Department of Agronomy and Plant Genetics