Germplasm Enhancement for RWA Resistance

D.W. Mornhinweg, and D.R. Porter

USDA-ARS Plant Science and Water Conservation Research Laboratory Stillwater, Oklahoma

Prebreeding for adapted germplasm lines

    The prebreeding program is designed to bring resistance genes from unadapted germplasm lines into adapted malting and feed barley backgrounds for all barley growing regions in the U.S. It involves repeated backcrossing with intermittent screening with a time commitment of approximately seven years from the first cross until homozygous resistant BC3F3 lines can first be evaluated as observation lines in the field. This is an ongoing process involving many resistant lines and adapted cultivars currently in all phases of the program.

    Field testing was preformed in cooperation with Phil Bregitzer (spring barley) and Darrell Wesenberg/Charles Erickson (winter barley) all scientists with the USDA-ARS in Aberdeen, Idaho; Bob Hammon and Frank Piears, Colorado State University; and David Baltensberger, University of Nebraska. In the summer of 2001, ten advanced generation RWA-resistant spring barley lines were evaluated in replicated yield trials at 4 locations in Idaho, 2 locations in Nebraska and 2 locations in Colorado. Five of these lines involved six, 6-row backrounds and five lines involved five, 2-row backgrounds with RWA resistance in all ten lines derived from STARS-9301B. Preliminary Yield Trials were conducted at one location in Idaho on a total of 33 adapted RWA-resistant winter barley germplasm lines involving three susceptible winter barley backgrounds and 9 RWA-resistant sources. Preliminary yield trials were conducted at 4 locations in Idaho for 187 advanced generation adapted spring barley germplasm lines involving 14 susceptible backgrounds and 23 RWA-resistant sources. A preliminary yield trial was conducted in Stoneham, Colorado on 114 adapted advanced generation RWA-resistant spring barley germplasm lines in an Otis background involving 3 different sources of RWA resistance. A 30 entry subset of these lines was also evaluated in a Preliminary yield trial in Aberdeen, Idaho.

    Five hundred and sixty advanced generation adapted winter RWA-resistant barley germplasm lines were evaluated in headrows at Aberdeen, Idaho and rows selected for future yield testing in 2002. These lines involved one susceptible background and 9 RWA-resistant sources. 1,000 adapted BC3F3/4 winter barley germplasm lines were evaluated in observation rows in Western Colorado involving 3 susceptible backgrounds and 7 RWA-resistant backgrounds and 600 adapted BC3F3/4 winter barley germplasm lines were evaluated in observation rows in Aberdeen, Idaho involving 2 susceptible background and 7 RWA-resistant backgrounds. Rows were selected for preliminary yield testing in 2002 and heads were selected for evaluation in headrows in 2002 in both Idaho and Colorado. 1,000 BC3F3/4 adapted spring RWA -resistant barley lines were evaluated in observation rows in Idaho. Selections were made for preliminary yield trials in 2002. Numerous adapted RWA-resistant spring barley germplasm lines were increased for pure seed in the field in Idaho and in the greenhouse in Stillwater, OK.

    Approximately 1,800 additional winter barley lines were increased in the greenhouse for possible inclusion as observation rows in 2003. These lines involved 4 susceptible parents and 15 RWA resistance sources. Another 1,090 spring barleys were also increased for possible inclusion as observation rows in 2003 involving 4 susceptible parents and 2 sources of RWA resistance. A total of 3,695 advanced generation spring barleys were increased for pure seed for potential release of 90 adapted germplasm lines. Six BC3F1 crosses were made for field evaluation as BC3F3 observation rows in 2003 in the prebreeding program. These crosses involved 6 susceptible spring barleys and 1 resistant source. Twenty-nine winter barley TC1F1 crosses were made for future genetic diversity studies. Four TC1F1 winter barley populations were selfed and increased for future genetic diversity studies. A total of 26,935 winter barley lines and 39,720 spring barley lines were screened in support of the prebreeding effort.

Genetic Studies

Complete genetic analysis has been performed on nine out of a total of 108 RWA -resistant lines developed by the USDA-ARS in Stillwater. All nine lines showed multiple gene control for RWA resistance. Seed has been developed and future genetic studies planned for the remaining 99 lines. Genetic diversity studies are also planned for all resistant lines to determine if these lines carry different genes for resistance to RWA. This type of analysis requires 3 years for development of seed necessary for each test. Twenty-nine winter barley TC1F1 crosses (susceptible winter barley/ resistant x resistant F1) were made for future genetic diversity studies. Four TC1F1 winter barley populations were selfed and increased for future genetic diversity studies.

Cooperative screening

Four hundred and six advanced lines were screened for resistance for 1 barley breeder.

Bird Cherry oat aphid

    Morphological measurements of BCOA effects on 1,308 barley seedlings/plants were collected towards an understanding of aphid/host interaction and the potential of a visual or measurable trait for future screening of barleys for BCOA resistance. Development of a greenhouse seedling screening test would make screening of large barley collections fast and effective for identification of BCOA-resistant barleys.

Personnel

Germplasm Enhancement

Dolores W. Mornhinweg, Geneticist
David R. Porter, Research Geneticist

Cooperators

Darrell Wesenberg, Research Agronomist, USDA-ARS, Aberdeen, ID
Phil Bregitzer, Research Geneticist, USDA-ARS, Aberdeen, ID
Berne Jones, Research Biochemist, USDA-ARS, Madison, WI
Frank Piears, Professor, Colorado State University
Bob Hammond, Professor, Colorado State University
Dave Blatsenberger, Professor, University of Nebraska

Recent Publications

Mornhinweg, D.W., D.R. Porter and J.A. Webster. 2002. Inheritance of Russian Wheat Aphid Resistance in Spring Barley Germplasm Line Stars-9577B. Crop Sci. (In Press).