OKLAHOMA
Germplasm Enhancement for RWA Resistance
D.W. Mornhinweg, D.R. Porter, J.A. Webster
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 and generational 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 various resistant lines and adapted cultivars currently in all phases of the program. Field testing is preformed in cooperation with Phil Bregitzer (spring barley) and Darrell Wesenberg (winter barley), both scientists with the USDA-ARS in Aberdeen, Idaho. In the summer of 2000, a total of 425 winter barley lines and 2,177 spring barley lines were evaluated as BC3F3/4 in observation rows. The winter lines involved 3 susceptible parents and 8 different sources of resistance to RWA. The extreme uniformity in these lines allowed selection of 33 rows for future evaluation in Preliminary Yield Trials in 2001. Heads were selected from an additional 135 rows for evaluation as headrows in Aberdeen in 2001 and from 22 rows for evaluation as headrows in Fruita, CO in the summer of 2001. Spring lines involved 13 susceptible parents and 12 different sources of RWA resistance. 275 lines were selected, evaluated for yield, and rescreened for homozygosity for potential entry into large preliminary yield trails in 2001. 115 lines in an Otis background were selected to be evaluated in preliminary yield trials in eastern CO in 2001. 392 spring barley headrows were evaluated in 2000 involving 9 susceptible parents and 18 different sources of RWA resistance. Seventy- two rows were selected for evaluation in Preliminary Yield trials in 2001 in Idaho. Twelve lines were evaluated in advanced yield trials at various locations in Idaho and another 10 lines were evaluated in advanced yield trails at two locations in Colorado. Selections from these trials have yet to be made. Following preliminary yield trials in 2001, there exists the potential for release of approximately 60 adapted RWA resistant germplasm lines in many cultivar backgrounds and with resistance to RWA from many sources.
Approximately 500 additional winter barley lines were increased in the greenhouse for possible inclusion as observation rows in 2001. These lines involved 3 susceptible parents and 4 RWA resistance sources. Another 450 spring barleys were also increased for possible inclusion as observation rows in 2001 involving 4 susceptible parents and 2 sources of RWA resistance. Six BC2F1 crosses were made for future field evaluation in the prebreeding program. These crosses involved 6 susceptible spring barleys and 1 resistant source. Eleven winter barley BC3F1 populations were increased to BC3F2 for future prebreeding efforts.
A total of nearly 6,000 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. Genetic diversity studies are 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. Six testcrosses of a resistant x resistant F1 on a susceptible were made in the spring of 2001. A total of 2,400 winter barley TC1F1:F2 involving 8 populations were increased for future genetic diversity studies, while 3,166 spring barley TC1F1:F2 involving 14 populations were also increased for future genetic diversity studies. Thirty-six RXR F1 crosses of resistant winter barleys and 5 RXR F1 crosses of resistant spring barleys were made for future genetic diversity studies.
Field evaluations
Forty-two advanced generation lines, developed cooperatively by Phil Bregitzer, UDSA-ARS Aberdeen, ID and USDA-ARS in Stillwater, were evaluated in replicated plots in Yellow Jacket, a dryland location in western Colorado, with the cooperation of Bob Hammond. Analysis is ongoing.
Twenty advanced generation lines, developed in cooperation with Phil Bregitzer, USDA-ARS Aberdeen, ID were tested in one dryland location and one irrigated location in Nebraska by Dave Blatensberger in 2000. Analysis is ongoing.
Cooperative screening
Five hundred and forty-six advanced lines were screened for resistance for 2 barley breeders.
Personnel
Germplasm Enhancement
Dolores W. Mornhinweg, Geneticist
David R. Porter, Research Geneticist
Host Plant Resistance
James A. Webster, Research Entomologist
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. 1998. Registration of Stars-9577B Russian Wheat Aphid Resistant Barley Germplasm. Crop Sci. 39: 882-883.
Mornhinweg, D.W., P.P. Bregitzer, B.L. Jones, F.B. Peairs, T.L. Randolph, D.R. Porter, and J.A. Webster. 1999. Effect of Early and Late RWA Infestation on Agronomics and Malting Quality of Adapted Barley Germplasm Lines. Proceedings 16th American Barley Researchers Workshop p. 69.