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

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 intermitent screening with a time commitment of approximately seven years from the first cross until homozygous resistant BC3F3 lines can be evaluated in the field. This is an ongoing process involving various resistant lines and adapted cultivars currently in all phases of the program. The summer of 1998 saw 28 lines in preliminary yield trials in the field in Aberdeen, ID with the cooperation of Darrell Wesenberg and Phil Bregitizer of the USDA-ARS. These lines were grown at two locations in Idaho with the potential for release of adapted germplasm lines or further testing and cultivar release. Of the 28 lines tested, 12 were greater than or equal to their adapted parent check for grain yield and plumps in Aberdeen, while in Tetonia, 22 lines were greater than or equal to their adapted parent check. Eleven of these lines were selected for advanced yield testing in 1999. Four of these lines, involving 2 resistant sources and 2 cultivars, were selected for further yield tests in 2000. Another 35 lines were advanced to preliminary yield tests in Idaho in the summer of 1999. Eight lines, greater than or equal in performance to their adapted parent were selected for advanced yield testing in 2000. These lines involved 3 cultivars and 3 sources of resistance. With anticipated selections from the 72 lines advanced from headrows in 1999 to preliminary yield trials in 2000, the potential exists for germplasm release of adapted RWA-resistant lines involving 7 culitvar backgrounds and 22 resistant backgrounds after the summer of 2000. The potential for release after the summer of 2001 would involve germplasm lines in an additional 10 cultivar backgrounds and 15 resistant backgrounds.

Three hundred sixty four headrows, selected in the previous year involving 22 resistant lines and 7 adapted cultivars, were evaluated and 72 lines were selected for preliminary yield testing in 2000. Seven hundred preliminary observation lines involving 7 different resistant sources and 6 adapted cultivars were evaluated for agronomics, and 209 lines were selected for head rows in 2000. Continuing with this program, 4,592 resistant BC3F2, involving 14 adapted cultivars and 15 resistant germplasm lines, were increased in the spring and summer of 1999 in the greenhouse in Stillwater. All 4,592 resultant BC3F3 lines, involving 10 adapted cultivars and 15 resistant germplasm lines, were screened for homozygous resistance in the fall of 1999 and the resultant 1800 homozygous resistant lines will be evaluated agronomically in Abdereen in the summer of 2000.

Ninety BC3F1 seedlings for each of 34 spring barley populations were screened in the fall of 1998 and 12 resistant plants from each population selected and increased in the winter of 1999 to obtain BC3F2 seed. Three hundred seedlings from each BC3F2 population were screened in the early spring and 100 resistant BC3F3 from each population selected and increased in the greenhouse. Eleven BC3F2 winter barley populations were increased in the greenhouse in the spring of 1999 and 1,624 BC3F3 were screened in the fall for field evaluation in 2000. Six BC3F1 for each of 6 winter barley populations were increased in the greenhouse for future field evaluation of adapted germplasm lines. Efforts are ongoing to develop RWA resistant barley germplasm. A total of 29 crosses were made for germplasm development: 4 BC3 on 3 cultivars, 19 BC2 on 8 cultivars, and 6 F1 with 6 cultivars

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. One F1 cross was made for future genetic studies. 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. Two RXR F1, and 34 testcrosses of a resistant x resistant F1 on a susceptible were made in the spring of 1999. Twelve TC1F1 populations were increased for future genetic diversity studies.

Previous field studies indicated that RWA feeding may have a negative effect on malting quality of RWA-resistant germplasm lines. Six agronomically adapted advanced generation RWA-resistant germplasm lines developed by Phil Bregitzer and Darrell Wesenberg with USDA-ARS in Aberdeen, ID in cooperation with the USDA-ARS lab in Stillwater, one unadapted RWA-resistant germplasm line developed by the Stillwater lab, and three adapted malting barley cultivars which were recurrent parents for the adapted germplasm lines were grown in Aberdeen, Idaho by Phil Bregitzer and Ft. Collins, CO with the cooperation of Frank Peairs and Colorado State Uninersity. Noninfested plots were kept RWA free with pre-plant seed treatment of Gaucho, while infested plots were artifically infested with RWA at an early or late date. The effect of RWA feeding on agronmics and malting quality of these lines was measured. One year of data indicates that yield and malting quality of adapted RWA-resistant germplasm lines was not affected by RWA feeding. Also the resistant germplasm lines out-yielded the susceptible parent check by as much as 94% on infested plots and were not significantly different in yield on noninfested plots. This study was repeated at both locations in 1999. Analysis is ongoing.

Three advanced generation lines developed jointly by Phil Bregitzer, USDA-ARS Aberdeen Idaho, and Stillwater ARS were evaluated by Frank Peiars in replicated tests at 6 dryland locations in Colorado and tested against Gaucho treated Otis and untreated Otis, the most commonly grown spring barley in the dryland areas of eastern Colorado before the insurgence of the RWA. Results varied with location and RWA infestation. The resistant lines, which were not developed from drought tolerant cultivars nor selected under dryland conditions, did not significantly out perform Otis in these dryland tests. Advanced generation lines in an Otis background will be in the field as observation lines in the summer of 2000.

Twenty-eight advanced generation lines, developed cooperatively by Phil Bregitzer, UDSA-ARS Aberdeen, ID and USDA-ARS in Stillwater, were evaluated in replicated plots at 2 dryland locations in western Colorado with the cooperation of Bob Hammond. In Fruita, 16 lines had yields greater than or equal to the highest yielding cultivar, Baronesse, and 24 lines yielded as high as or higher than Garnet. In Yellow Jacket, 21 lines yielded greater than or equal to Stander, the highest yielding cultivar, and 25 lines yielded as high or higher than Baronesse. Many of these lines will be tested again in 2000.

Twenty-three advanced generation lines, developed in cooperation with Phil Bregitzer, USDA-ARS Aberdeen, ID were tested in one dryland location in Nebraska by Dave Blatensberger in 1999. Eight lines yielded as high as or higher then Baronesse and Steptoe and 10 lines yielded as high as or higher than Stander.

Six hundred eighty-four advanced lines were screened for resistance for two barley breeders.

Germplasm Enhancement

Dolores W. Mornhinweg, Geneticist

David R. Porter, Research Geneticist

Host Plant Resistance

James A. Webster, Research Entomologist

Keith A. Mirkes, Biological Science Technician

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

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