Annual Progress Report on Malting Barley Research March, 2002

104
BARLEY VIRUS DISEASES
Michael C. Edwards
USDA-ARS Cereal Crops Research Unit, Red River Valley Agricultural Research
Center, and Department of Plant Pathology, North Dakota State University, Fargo, North
Dakota.
Objectives/Rationale
The ultimate goal of this research program remains unchanged from previous years. That
goal is to reduce barley losses that occur as a result of virus diseases. Our objectives and
rationale therefore remain unchanged. Virus diseases continue to result in significant
yield losses in barley and other cereals. Because significant improvement in our ability
to control virus diseases depends to a great extent upon significant improvement in our
understanding of how viruses function and cause disease, this research program
emphasizes molecular genetic studies of host-virus interactions. The goal of these studies
is to identify the factors involved in viral pathogenicity and host resistance. Our studies
primarily involve barley stripe mosaic virus (BSMV) and oat blue dwarf virus (OBDV).
Because we have evidence that resistance to BSMV is targeted to basic processes such as
virus replication and movement, just as is the case with other viruses, we feel there is
much to gain from studying this virus as a model. Like barley yellow dwarf virus,
OBDV is present in barley fields every year, albeit to a much lesser extent. Also like
BYDV, OBDV is limited to the phloem of infected plants. Thus, certain aspects of
OBDV pathogenesis may be similar to that of BYDV.
Another goal of our project is to eliminate BSMV infections from the barley in the
National Small Grains Germplasm Collection (in cooperation with ARS personnel in
Idaho [Drs. Wesenberg & Bockelman]). The NSGGC serves as a valuable source of new
germplasm for the improvement of malting barley varieties as well as others. Many of
the barley entries are infected with BSMV, a seed-borne pathogen. Since clean seed
stocks are vital for effective control of BSMV, it is extremely important to maintain the
collection in a BSMV-free condition. Thus, we will attempt to identify all entries
infected with BSMV and eliminate BSMV from seed stocks of these entries. Sources of
tolerance to BSMV ultimately may be identified as well.
Another goal of our program is to facilitate the development of new malting barleys
adapted to the upper Midwest through the coordination of the Mississippi Valley Uniform
Regional Barley Nursery.
Methods
For evaluation of the NSGGC, procedures involve the evaluation of accessions (or
entries) for the presence of BSMV, rogueing of infected plants, and production of
BSMV-free seed. In most past years, 2000 new entries were grown in field plots at the
USDA-ARS National Small Grains Germplasm Research Facility in Aberdeen, Idaho.
We had originally planned to attempt the production of virus-free seed from known
infected accessions using methods similar to those used last year and first used in 1997.
This normally involves planting each accession in hills to minimize the possibility of