Shawn Mehlenbacher

The OSU Hazelnut Breeding program develops new cultivars for Oregon's hazelnut industry, with an emphasis on resistance to eastern filbert blight (EFB) and suitability for the kernel market.

Plant Breeding: Develop new cultivars for Oregon's hazelnut industry, with emphasis on resistance to eastern filbert blight (EFB) and suitability for the kernel market. Practice marker-assisted selection using robust DNA markers linked to the dominant resistance allele from 'Gasaway'. Use new sources of EFB resistance in breeding, including quantitative resistance. Improve breeding methods and efficiency. Collect hazelnut germplasm from around the world, evaluate, and use interesting accessions as parents in breeding. Cooperate with Rutgers University, the University of Nebraska at Lincoln, and the National Arbor Day Foundation to develop interspecific hazelnut hybrids (Corylus americana x C. avellana) adapted to eastern North America.

Plant Genetics. Identify additional sources of resistance to eastern filbert blight, study genetic control, and identify or develop DNA markers linked to the new sources of resistance. Develop microsatellite markers and assign the loci to linkage groups. Use microsatellite markers to fingerprint accessions and study genetic variability in Corylus. Obtain information on the genetic control of traits. Identify the S-alleles that control pollen-stigma incompatibility in hazelnut cultivars and selections. Perform fine mapping and map-based cloning of the incompatibility in hazelnut, and investigate its molecular basis. Perform fine mapping and map-based cloning of EFB resistance from three sources ('Gasaway', 'Ratoli' and Georgian OSU 759.010) and investigate its molecular basis. Cooperate with colleagues in sequencing the genomes of several hazelnut cultivars and selections. 

Courses Taught:

I teach Plant Breeding (PBG 450/550) annually and Breeding Clonal Crops (PBG 551) in alternate years. I contribute to Temperate Tree Fruits, Berries, Grapes and Nuts (Hort 251), World Food Crops (CSS 330). Research and Educational Perspectives in Horticulture (HORT 511).

Book Chapter:

Botta, R., T.J. Molnar, V. Erdoğan, N. Valentini, D. Torello Marinoni and S. Mehlenbacher.  2019.  Chapter 6, Hazelnut (Corylus spp.) breeding.  p. 157-219.  In:  J.M. Al-Khayri, S.M. Jain, and D.V. Johnson (eds.).  Advances in Plant Breeding Strategies, Vol. 4.: Nut and Beverage Crops.  doi.org/10.1007/978-3-030-23112-5_6 

Journal Articles (2020) 

Revord, R.S., S.T. Lovell, J.M. Capik, S. Mehlenbacher and T.J. Molnar.  2020.  Eastern filbert blight resistance in American and interspecific hybrid hazelnuts.  J. Amer. Soc. Hort. Sci.  145:  (in press). 

Journal Articles (2019) 

Honig, J.A., M.F. Muehlbauer, J.M. Capik, C. Kubik, J.N. Vaiciunas, S. A. Mehlenbacher, and T.J. Molnar.  2019.  Identification and mapping of eastern filbert blight resistance quantitative trait loci in European hazelnut using double digestion restriction site associated DNA sequencing.  J. Amer. Soc. Hort. Science 144(5):295-304.  doi.org/10.21273/JASHS04694-19

Molnar, T.J., S. Mehlenbacher, P. Engel, and J. Capik.  2019.  Multiple sources of eastern filbert blight resistance provide breeding utility in New Jersey.  J. Amer. Pomol. Soc. 73(3): 178-192. 

Mehlenbacher, S.A., D.C. Smith and R.L. McCluskey.  2019.  'PollyO' hazelnut.  HortScience 54:1429-1432. 

Journal Articles (2018)

S. A. Mehlenbacher, Smith, D. C., and McCluskey, R. L., “‘Burgundy Lace’ Ornamental Hazelnut”, HortScience, vol. 53, no. 3, pp. 387 - 390, 2018.

Muehlbauer, M., J.M. Capik, T.J. Molnar and S.A. Mehlenbacher.  2018.  Assessment of the ‘Gasaway’ source of resistance to eastern filbert blight in New Jersey.  Scientia Horticulturae 235:367-372. 

Bhattarai, G. and S.A. Mehlenbacher.  2018.  Discovery, characterization and linkage mapping of simple sequence repeat markers in hazelnut.  J. Amer. Soc. Hort. Sci. 143:347-362. doi.org/10.21273/JASHS04461-18 

Mehlenbacher, S.A., D.C. Smith and R.L. McCluskey.  2018.  'York' and 'Felix' hazelnut pollenizers.  HortScience 53:904-910.  doi: 10.21273/HORTSCI12836-18

Mehlenbacher, S.A.  2018.  Advances in genetic improvement of hazelnut.  Acta Hort. 1226:1-12. 

Snelling, J., V. Sathuvalli, G. Bhattarai, E. Rowley, T. Mockler, C. Saski, D. Copetti and S.A. Mehlenbacher.  2018.  Genomic resource development in hazelnut breeding.  Acta Hort. 1226:39-45. 

Smith, D.C., R.L. McCluskey and S.A. Mehlenbacher.  2018.  New hazelnut cultivars from Oregon State University.  Acta Hort. 1226:47-52.   

Mehlenbacher, S.A.  2018.  Breeding hazelnuts resistant to eastern filbert blight.  Acta Hort. 1226:73-78.  

Molnar, T.J., J.J. Lombardoni, M.F. Muehlbauer, J.A. Honig, S.A. Mehlenbacher and J.M. Capik.  2018.  Progress in breeding for resistance to eastern filbert blight in the eastern United States.  Acta Hort. 1226:79-85.   

Gürcan, K., S.A. Mehlenbacher, M.A. Köse and H.I. Balık.  2018.  Population structure analysis of European hazelnut (Corylus avellana).  Acta Hort. 1226:87-92. 

Mehlenbacher, S.A. and G. Bhattarai.  2018.  An updated linkage map for hazelnut with new simple sequence repeat markers.  Acta Hort. 1226:31-37. 

Molnar, T.J., J.A. Honig., A. Mayberrry, R.S. Revord, S.T. Lovell, S.A. Mehlenbacher and J.M. Capik.  2018.  Corylus americana:  a valuable genetic resource for developing hazelnuts adapted to the eastern United States.  Acta Hort. 1226:115-121. 

Rowley, E.R., R. VanBuren, D.W. Bryant, H.D. Priest, S.A. Mehlenbacher, and T.C. Mockler.  2018.  A draft genome and high-density genetic map of European hazelnut (Corylus avellana L.).  BioRxiv preprint posted on-line 11 Dec. 2018.