OKLAHOMA

Germplasm Enhancement for RWA Resistance

D.W. Mornhinweg and D.R. Porter

USDA-ARS Wheat, Peanut and Other Field Crops Research Unit

Stillwater, Oklahoma

Prebreeding for adapted germplasm lines (RWA 1)

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 RWA screening, of developed resistant lines to cultivars adapted to barley production areas, with a time commitment of approximately seven years from the first cross until BC3F3 lines can first be evaluated as observation lines in the field. Spring lines can be developed at an accelerated pace because of the potential for 2 generations per season. Once selections have been made in applicable field locations, these lines enter replicated preliminary yield trials for several years before final selections are made for germplasm release. Three hundred head selections were made from 7 selected winter barley lines. Seed from these heads were screened for homozygous resistance and remnant seed bulked for release. When bulked seed was not enough for release, resistant plants were rescued and seed increased to be screened again prior to bulking. These 7 lines, in a Schuyler background, were released by USDA-ARS, Stillwater and USDA-ARS, Aberdeen in August of 2005. With 98 potential spring germplasm lines, head selections were intimidating. Instead, seed from selected lines was tested for homozygous resistance. If not homozygous, plants were rescued from screening, and increased in the greenhouse to be screened again before bulking. The number of releases was culled to 43 (19 six row malt, 17 two row malt, and 7 two row feed) and the spring of 2006 should see the last seed increases prior to release by USDA-ARS, Stillwater in cooperation with Phil Bregitzer, USDA-ARS, Aberdeen. Another 9 winter barley lines have been selected from preliminary yield trials in cooperation with Don Obert, USDA-ARS, Aberdeen. These lines are in a Post 90 background and are resistant to both RWA and greenbug. Testing for homozygous resistance to both aphids is under way and release should be in 2007. Several spring and winter barleys from the prebreeding program are in elite field trials of Phil Bregitzer and Don Obert, USDA-ARS, Aberdeen with the prospect of cultivar release.

‘Stoneham’ and ‘Sidney’ barleys were released in the spring of 2006 by USDA-ARS, Stillwater, USDA-ARS, Aberdeen, Colorado State University, and University of Nebraska. These cultivars were developed from the prebreeding program. Breeders’ seed was increased by Colorado Foundation Seeds and Nebraska Foundation Seeds in the summer of 2005. Sidney and Stoneham are drought hardy, RWA-resistant cultivars developed for the hot, dry, high plains of eastern Colorado and western Nebraska. Both have RWA resistance in an Otis background. Sidney has resistance from STARS 9301B and Stoneham has resistance from STARS 9577B. Resistance in both lines holds up to all the currently described RWA biotypes.

RWA Biotypes

Recent surveys of the high plains states have shown RWA1 and RWA2 to exist in substantial numbers. All germplasm releases from this program are screened to both biotypes. STARS 9301B and STARS 9577B were tested against RWA3, RWA4, and RWA5 by Gary Puterka, USDA-ARS, Stillwater. Both lines were resistant to all biotypes.

Genetic Studies

RWA

Complete genetic analysis, using RWA 1, has been performed on nine out of a total of 109 RWA 1-resistant lines developed by the USDA-ARS in Stillwater. All nine lines showed multiple gene control for RWA1 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 RWA1. Multiple allelism testing requires 3 years for development of populations necessary for each test. The first test for multiple allelism was preformed in the winter of 2004 for STARS-9301B and STARS-9577B. Inheritance studies for each line indicated 2 genes control RWA resistance in each line. Parents, F1 (STARS 9301B/STARS 9577B), reciprocal F1, F2, TC1F2, and TC1F1:F2 families were screened with RWA1. Multiple allelism analysis indicated 4 distinct genes (or alleles).

Lynn Dahleen, USDA-ARS Fargo, ND, is cooperating to map the genes for resistance in these 2 lines. As a part of that project, each line was crossed as a male to Morex and 300 F2:F3 families from each population were grown and phenotyped for RWA1 resistance. Remnant seed was sent to North Dakota for mapping. Analysis is on going. A second phenotyping was done on the F2:F3 of the Morex/STARS 9301B population in the spring of 2006. Seed from the Morex/STARS 9577B population was not viable and as a result, three hundred F2:F3 families were increased for the Morex/9577B population in the spring of 2006. Phenotyping is planned in the spring of 2007.

Bulks of 109 unadapted RWA resistant germplasm lines, developed by USDA-ARS, Stillwater, were screened for resistance and plants rescued for increase to maintain viable seed of each line. 5,000 heads from a total of 13 potential germplasm releases were screened for RWA1 and resistance.

Greenbug

Genetic populations continue to be developed to determine the inheritance of greenbug biotype G resistance in three lines, Wintermalt, Bancroft and Colter.

The source of Rsg2 resistance in barley is PI 426756. This accession is heterozygous for greenbug resistance. Sixty-nine plants of PI 426756 were screened for resistance to greenbug biotype E and seedlings from homozygous resistant plants rescued and increased in the greenhouse.

Cooperative screening

Four hundred and twenty one accessions were screened to RWA1 and greenbug for the National Small Grains Collection. Twenty five winter barleys were screened to RWA1 and greenbug for Virginia Polytechnic Institute and State University. Thirteen hulless winter barleys were screened for An Hang, USDA-ARS, Aberdeen. One hundred and thirty-three advanced lines were screened to RWA1 for Phil Bregitzer, USDA-ARS, Aberdeen.

Bird Cherry oat aphid

BCOA damage to barley seedlings is morphologically symptom-less. As a result, traditional seedling screening techniques are not successful in identifying BCOA resistant barleys. Development of a greenhouse seedling screening test would make screening of large barley collections fast and effective for identification of BCOA-resistant barleys. A new screening technique was tested on 78 barley accessions with 2 treatments (infested and non-infested) and 3 replications in the summer of 2005. This technique was unique in that the screening occurred under high temperatures and long day lengths of June in Oklahoma. Many lines tested, including Morex, were killed by the aphids while the non-infested controls grew normally. A subset of 63 lines was then grown in 2 different types of screening flats in July. Non-infested controls were grown for each flat type as well. Seed did not germinate in one flat type. Morex, used as a susceptible check, as well as many other lines, died in the infested soil flat while other lines survived. Development of all surviving lines was greatly delayed compared to the non-infested controls. Another soil flat trial was conducted in January of 2006 and again all Morex checks died. A rating scale was developed based on 1 to 7 where 1=green and turgid seedling and 7=dead seedling. This screening technique has promise for identifying BCOA resistance in barley.

Hulless winter barley for ethanol

There is new interest in winter hulless barley in Oklahoma for ethanol production. Byproducts have the potential to be used for cattle, hog, or chicken feed as well as human nutrition. Few winter hulless barley varieties exist in the country. A breeding program was begun in 2004 to identify hulless winter barley accessions which could be utilized in a breeding program to bring the hulless trait into winter barley adapted to Oklahoma. Winter barley production in OK would be dryland and resistance to GB as well as RWA would be desired. Post 90 is a greenbug resistant, winter, hulled barley released by Oklahoma State University and USDA-ARS, Stillwater in 1990. USDA-ARS, Stillwater, has developed RWA-resistant lines in a Post 90 background which have been shown to be superior to Post 90 in grain yield. Eight hundred and seventy one winter hulless barley accessions from the NSGC were evaluated for winter survival in Oklahoma in 2004. Selected lines were used in crossing to RWA-resistant, Post 90 lines in the spring of 2005. Specifically, 10 hulless winter barleys were crossed to 18 RWA-resistant Post 90 lines with resistance to RWA from 9 different sources. Seventy-eight winter hulless lines, previously selected for winter survival in Oklahoma, were evaluated in a yield trial with 4 replications at 2 northern OK locations in the summer of 2005. An additional 113 lines were tested in replicated yield trials at one location and 91 single rows, were evaluated for agronomics at one location. Fifty-four hulled RWA and greenbug resistant lines were also evaluated at 2 locations in OK. 3,000 RWA1 resistant Post 90 lines were screened to GBE and RWA. Resistant plants were rescued and increased in the greenhouse.

Personnel

Germplasm Enhancement

Dolores W. Mornhinweg, Research Geneticist

David R. Porter, Research Geneticist

Cooperators

Don Obert, Research Geneticist, USDA-ARS, Aberdeen, ID

Phil Bregitzer, Research Geneticist, USDA-ARS, Aberdeen, ID

Frank Piears, Professor, Colorado State University

Bob Hammond, Professor, Colorado State University

Dave Baltensperger, Professor, University of Nebraska

Gary Hein, Professor, University of Nebraka

Lynn Dahleen, Research Geneticist, USDA-ARS, Fargo, ND

Gary Puterka, Research Entomologist, USDA-ARS, Stillwater

Recent Publications

Bregitzer, P, D.W. Mornhinweg, and B.L. Jones. 2003. Resistance to Russian Wheat Aphid Damage Derived from STARS-9301B Protects Agronomic Performance and Malting Quality When Transferred to Adapted Barley Germplasm. Crop Sci. 43: 2050 – 2057.

Mornhinweg, D.W., L.H. Edwards, E.L. Smith, G.H. Morgan, B.F. Carver, J.A. Webster, and D.R. Porter. 2004. Registration of Post 90 Barley. Crop Sci. 44: 2263.

Porter, D.R., and D.W. Mornhinweg. 2004. New sources of Greenbug Resistance in Barley. Crop Sci. 44: 1245-1247.

Porter, D.R., and D.W. Mornhinweg. 2004. Characterization of greenbug resistance in barley. Plant Breeding 23(5): 493-494.

Mornhinweg, D.W., M.J. Brewer, and D.R. Porter. 2006. Effect of Russian wheat aphid on yield and yield components of field grown susceptible and resistant spring barley. Crop Sci 46:36-42.

Mornhinweg, D.W., D.E. Obert, D.M. Wesenberg, C.A. Erickson, and D.R. Porter. 2006. Registration of seven winter feed barley germplasms resistant to Russian wheat aphid. Crop Sci. 46:1826-1827.