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.  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. 

 

Another 9 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. 

 

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.  Seed is available through Colorado Foundation Seeds and Nebraska Foundation Seeds.  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 Biotypes

 

In 2003, a new biotype of RWA (RWA2) was identified on previously RWA-resistant wheat cultivars in Colorado.  Recent surveys of the high plains states have shown both RWA1 and RWA2 to exist in substantial numbers.  Three more biotypes have been described in wheat since that time (RWA3, RWA4, and RWA5).  In 2006, the 43, spring germplasm releases from this program were screened to all 5 wheat biotypes by Gary Puterka, research entomologist, USDA-ARS, Stillwater.   All lines were resistant to all biotypes.  RWA biotypes on barley have been identified in other parts of the world.   So far, in the US, barley biotypes have yet to arise.   

 

Genetic Studies

 

RWA

 

Complete genetic analysis, using RWA 1, has been performed on 11 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 98 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 indicates 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.  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, 300 F2:F3 families were increased for the Morex/9577B population in the spring of 2006 and phenotyped twice in the spring of 2007.

 

 

 

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.   

 

 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, GB01, and Wintermalt, were tested against 12 biotypes of greenbug in cooperation with John Burd, research entomologist, USDA-ARS, Stillwater.  A unique response matix from the differentials would be an indication of new genes for greenbug resistance.  Analysis is ongoing. 

 

Cooperative screening

 

Four hundred and twenty one accessions were screened to RWA1 and greenbug for the National Small Grains Collection.   189 advanced lines were screened to RWA1 for Phil Bregitzer, USDA-ARS, Aberdeen.  181 lines were phenotyped for Bertrand Collard, Hermitage Research Station, NSW.  210 NSGC accessions were screened to greenbug 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, 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.  Analysis is ongoing. 

 

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. Preliminary yield trials continued in 2006 at two locations in OK to identify the best agronomic performers for use in a backcross breeding program.  Eight hundred and seventy one winter hulless barley accessions from the NSGC were evaluated for winter survival in Oklahoma in 2004.  Preliminary yield trials were conducted with selected lines at two locations in OK in 2005 and 2006.  Selected lines were used as males in crossing to RWA-resistant, Post 90 lines in the spring of 2005, 2006, and 2007.  In the spring of 2007, 34 backcrosses and 146 F1 were made involving 26 hulled RWA and greenbug resistant lines and 19 hulless lines. 

 

Personnel

 

Germplasm Enhancement

            Dolores W. Mornhinweg, 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

            John Burd, 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.

 

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.