OKLAHOMA

Germplasm Enhancement for RWA Resistance

D.W. Mornhinweg

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. Because of the potential in aphids to develop new biotypes, many different sources of resistance were utilized in the backcross breeding program. It involves repeated backcrossing, with intermittent RWA screening, of unadapted RWA-resistant lines as males to cultivars adapted to barley production areas as females, 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.

Seven, RWA-resistant winter feed barley germplasm lines (STARS 0501B – STARS 0507B) were released in 2005. These lines involved 7 different sources of resistance each in a Schuyler background. In 2006, 43 RWA-resistant spring germplasm lines were released. STARS 0601B – STARS 0619B involved 19 different sources of resistance in 4, spring, 6-rowed,malting barely backgrounds - Excel, Morex, Robust and Stander. STARS 0620B –STARS 0636B involved 17 different sources of resistance in 4, spring, 2-rowed, malting barley backgrounds – B1202, Crest, Crystal, and Harrington. STARS 0637B – STARS 0643B involved 5 different sources of resistance in 3, spring, 2-rowed, feed barley backgrounds – Bowman, Hector, and Otis. The 2006 spring germplasm releases involved 31 different sources of RWA resistance and the winter germplasm lines another 5 sources. The determination of the number of different genes in these 36 lines is underway.

Thirteen winter barley lines have been selected from preliminary yield trials in cooperation with Don Obert, USDA-ARS, Aberdeen, in 2005. These lines are in a Post 90 background and are resistant to both RWA and greenbug. Screening for homozygous resistance to both aphids and seed increase is underway prior to germplasm release.

‘Burton’, a 2-rowed, spring feed barley released in 2004 cooperatively by USDA-ARS Aberdeen, USDA-ARS- Stillwater, Idaho, Colorado, Nebraska, and New Mexico Agricultural Experiment Stations, was the first RWA-resistant barley cultivar developed in the US. Burton has resistance from STARS 9301B. ‘Stoneham’ and ‘Sidney’ barleys were released in the spring of 2006 by USDA-ARS, Stillwater, USDA-ARS, Aberdeen, and the Colorado and Nebraska Agricultural Experiment Stations. 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 hold up to all the currently described RWA biotypes. ‘RWA 1758’, a 2-rowed, spring feed barley in Baronesse background was released cooperatively by USDA-ARS Aberdeen and USDA-ARS Stillwater. RWA1758 has resistance from STARS 9577B. These three cultivars were developed from the prebreeding program. Several other 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.

Genetic Studies

RWA

Inheritance studies were conducted for two RWA-resistant germplasm lines in the spring of 2007. Analysis is ongoing. Complete genetic analysis had been performed previously for 11 out of a total of 116 RWA 1-resistant lines developed by the USDA-ARS in Stillwater. All eleven lines showed multiple gene control for RWA1 resistance. Seed has been developed and future genetic studies planned for the remaining 103 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 seed 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).

In a cooperative project, Lynn Dahleen, USDA-ARS Fargo, mapped the genes for resistance in STARS 9301B and STARS 9577B. Phenotyping for each population was performed in Stillwater. Three QTLs for RWA resistance were identified in STARS 9301B. Two of the same QTLs were identified for resistance in STARS 9577B.

A cooperative project was initiated with Yiqun Weng at Texas AgriLife Research to identify and map QTL for RWA and greenbug resistance. DNA was sampled from 200 F2 of 3 populations each with Rsg1 resistance to greenbug and a different source of RWA resistance. F2 from each population were phenotyped for RWA and greenbug resistance. Analysis is ongoing.

Greenbug

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

Post 90 winter barley has Rsg1 resistance. The source of Rsg2 resistance in barley is PI 426756. This accession is heterozygous for greenbug resistance. Progeny from resistant selections out of PI 426756 were screened to greenbug biotype E and seedlings from homozygous resistant plants rescued, increased, and bulked in the greenhouse. This homozygous source of Rsg2 resistance was designated GB02. GB02 is a 6-rowed spring barley. GB02 was crossed as a male to Weskan to develop winter barley with Rsg2 resistance. One population with Rsg2 resistance was developed for future mapping of that gene in cooperation with Texas AgriLife Research.

Twenty-nine hulless winter barley accessions from the NSGC were identified with resistance to greenbug biotype E. In the spring of 2007, these 29 lines plus the barley differentials, Post 90, GB02, and Wintermalt, were tested against 12 biotypes of greenbug in cooperation with John Burd, research entomologist, USDA-ARS, Stillwater. Five lines showed a unique response matix to standard differentials indicating new genes for greenbug resistance. Genetic populations are being developed to determine inheritance and genetic diversity of these resistant sources.

Cooperative screening

336 advanced lines were screened to RWA1 for Phil Bregitzer, USDA-ARS, Aberdeen. 210 NSGC accessions were screened to RWA1 for Harold Bockelman, 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 seedling screening technique has been developed in Stillwater and a rating scale of 1 to 7 defined where 1=green and turgid seedling and 7=dead seedling. A sub-sample of the barley core collection (960 lines) was screened twice in the summer of 2006. All seedlings with ratings from 1 – 6 were rescued. Three weeks later, 900 seedlings that survived rescue were transplanted into pots and grown to maturity in the greenhouse. Plant height, grain yield and yield components were measured in the spring of 2007.

Five seedlings each from the highest yielding plants of each of 364 accessions were screened in the summer of 2007 to determine the accuracy of the 1-7 rating scale in identification of resistance and prediction of grain yield. An identical set of seedlings was grown in the same greenhouse and kept aphid free by insecticide application. Seedlings were rated with the 1-7 scale and plant height and leaf number recorded. Seedlings with ratings from 1-5 were rescued and survivors transplanted in pots and placed side by side with noninfested controls. Plants were grown to maturity and grain yield, yield components, and plant height were measured. Analysis is ongoing.

Hulless winter barley for ethanol

There is new interest in winter hulless barley in Oklahoma for ethanol production. Byproducts (DDGS) 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. Preliminary yield trials continued in 2007 at two locations in OK to identify the best agronomic performers for use in a backcross breeding program. Head selections were made from 35 F2 bulks. 1,874 hulless F3 heads were screened for RWA and greenbug resistance and 4,000 resistant F3 seedlings were reared in the greenhouse in the spring of 2007. 105 F2 bulks were planted in the field in the fall of 2007 for head selection in the summer of 2008. 104 F1 were increased to F2. Selected hulless lines from 2007 yield testing were used as males in crossing to selected RWA-resistant, Post 90 lines in the spring of 2008. 89 backcrosses and 189 F1 were made involving 5 hulled greenbug resistant lines, 37 RWA /greenbug resistant lines and 12 hulless lines.

Personnel

Germplasm Enhancement

Dolores W. Mornhinweg, 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

Yiqun Weng, Texas AgriLife Research

Gary Hein, Professor, University of Nebraka

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

Gary Puterka, Research Entomologist, USDA-ARS, Stillwater, OK

John Burd, Research Entomologist, USDA-ARS, Stillwater, OK

Tim Springer, Research Geneticist, USDA-ARS, Woodward, OK

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.

Bregitzer, P., D.W. Mornhinweg, R. Hammon, M. Stack, D.D. Baltensperger, G.L. Hein, M.K. O’Neill, J.C. Whitmore, and D.J. Fiedler. 2005. Registration of ‘Burton’ Barley. Crop Sci. 45: 1166-1167.

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.

Mornhinweg, D. W., Bregitzer, P. P., and Porter, D. R. 2007. Registration of seventeen spring two-rowed barley germplasm lines resistant to Russian wheat aphid. J. Plant Reg. 1(2): 135-136.

Mornhinweg, D. W., Bregitzer, P. P., and Porter, D. R. 2006. Registration of nineteen spring six-rowed barley germplasm lines resistant to Russian wheat aphid. J. Plant Reg. 1(2): 37-138.

Porter, D. R., Burd, J. D., and Mornhinweg, D. W. 2007. Differentiating greenbug resistance genes in barley. Euphytica 153:11-14.

Shufran, K.A., Mornhinweg, D. W., Baker, C. A., and Porter, D. R. 2007.

Variation to cause host injury between Russian wheat aphid (Homoptera: Aphididae) clones virulent to Dn4 wheat. J. Econ. Entomol. 100(5):1685-1691.

Bregitzer, P., Mornhinweg, D. W., Obert, D. E., and Windes, J. 2008. Registration of ‘RWA 1758’ Russian wheat aphid-resistant spring barley. J. Plant Reg. 2(1):5-9.

Mittal, S., Dahleen, L. S., and Mornhinweg, D. W. 2008. Locations of quantitative trait loci (QTL) conferring Russian wheat aphid resistance in barley germplasm STARS 9301B. Crop Sci: 48: 1452-1458.

Mornhinweg, D.W., Bregitzer, P., and Porter, D. R. Registration of seven spring two-rowed barley germplasm lines resistant to Russian wheat aphid. J. Plant Reg. 2(3):135-136.