Redesigned Barley Has Potential to Thwart Scab Disease

Agricultural Research Service scientists are “seeing spots” while redesigning barley using natural proteins with the potential to thwart a costly disease-causing fungus. Scab, caused by the fungus Fusarium graminearum, inflicts losses of more than a billion dollars to barley, wheat, oats, rye, and corn annually.

Seeing spots in plants is a good sign that scientists can target the expression of genes in a specific area rather than in the whole plant. F. graminearum begins damaging barley in the leafy area surrounding the barley seed.

ARS molecular biologist Ronald Skadsen in Madison, Wis., has cloned hordothionin, an antifungal protein gene found inside the barley kernel. Skadsen has demonstrated hordothionin’s detrimental effect on the scab fungus. A postdoctoral scientist working with Skadsen developed a gene promoter, dubbed D5, to help target expression of hordothionin. This is a necessary step before inserting the antifungal gene, according to Skadsen.

They attached a green fluorescent protein, called gfp, from a jellyfish to the D5 promoter. With a gene gun, they blasted the pair into the leafy area that surrounds the seed. Within a day, they saw hundreds of green spots, confirming that gfp was being expressed in the target area. Next, hordothionin will be added in place of the jellyfish gene. Next summer, transformed barley containing hordothionin will be checked for its ability to resist Fusarium.

Skadsen discussed these research findings at the 1999 National Fusarium Head Blight Forum in Sioux Falls, S.Dak., Dec. 6-8. For more information, visit the web site of the U.S. Wheat and Barley Scab Initiative.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.

Scientific contact: Ronald W. Skadsen, ARS Cereal Crops Research Unit, 501 Walnut St., Madison, WI 53705, telephone (608) 262-3672, fax (608) 264-5528, rskadsen@facstaff.wisc.edu.