Research Interests | Publications | Professional Experience | Courses Taught

Research Interests
Breed new cultivars for Oregon's hazelnut industry, improve breeding methods, document genetic variability in Corylus, develop DNA markers and use them to characterize hazelnut cultivars, identify new sources of disease resistance and use them in breeding, conduct DNA marker-assisted selection for disease resistance, identify incompatibility alleles in hazelnut cultivars and selections. Import and evaluate hazelnut germplasm from around the world and use interesting accessions as parents in breeding.

I will continue to develop new hazelnut cultivars for the Oregon hazelnut industry that combine suitability to the blanched kernel market with resistance to eastern filbert blight. The response of additional hazelnut accessions to eastern filbert blight inoculation will be assessed, and new sources of resistance used in breeding. DNA markers are now used to identify seedlings that carry the 'Gasaway' resistance gene prior to field planting. We have identified markers linked to other dominant resistance alleles, and will soon implement marker-assisted selection. Eventually we will use DNA markers to pyramid different resistance genes. Microsatellite loci are being developed and used to "fingerprint" hazelnut cultivars, and the loci will be placed on our linkage map. We have a BAC library for hazelnut, and will soon initiate map-based cloning of the eastern filbert blight resistance and pollen-stigma incompatibility loci.

Hazelnut (the genus Corylus) could serve as a model for genomics studies in the family Betulaceae and the order Fagales. The family Betulaceae includes the economically important forest tree genera Betula (birch) and Alnus (alder) and minor genera Carpinus (hornbeam), Ostrya (hophornbeam) and Ostryopsis. The order Fagales includes the families Fagaceae, Juglandaceae and Betulaceae. The family Fagaceae includes Fagus (beech), Castanea (chestnut) and Quercus (oak). The family Juglandadeae includes Juglans (walnut) and Carya (pecan and hickory). Corylus avellana is a diploid (2n=2x=22). Its small genome (0.48 pg/1C nucleus, 413 Mb) is about 2.5 times that of Arabidopsis (0.18 pg/1C nucleus, 125 Mb) and slightly smaller than rice (0.50 pg/1C nucleus, 430 Mbp). The USDA and OSU hazelnut collections in Corvallis are the best in the world, and include representatives of all important Corylus species and over 450 clones of the commercially important European hazelnut, Corylus avellana. The OSU hazelnut breeding program was begun in 1969. An average of 5000 seedlings (100 seedlings from each of 50 controlled pollinations) has been planted each year in the past decade. Cultivars are highly heterozygous and clonally propagated. We have identified many simply inherited traits and estimated heritability of quantitative traits. A linkage map for hazelnut was constructed using the double pseudo-testcross strategy and RAPD and SSR markers for a population (n=144) created by crossing two highly heterozygous parent clones. We have developed about 150 microsatellite marker loci, and have placed 29 on the linkage map. Twenty-one markers have been used to fingerprint 270 hazelnut accessions and study genetic diversity in the collection. Microsatellite markers show transferability across genera in the Betulaceae.

Publications
Gökirmak, T., S.A. Mehlenbacher and N.V. Bassil. 2007. Characterization of European hazelnut (Corylus avellana) cultivars using SSR markers. J. Amer. Soc. Hort. Sci. 131: (in preparation)

Mehlenbacher, S.A., A.N. Azarenko, D.C. Smith and R.L. McCluskey. 2007. 'Santiam' Hazelnut. HortScience 42: (submitted)

Mehlenbacher, S.A. 2007. Hazelnut. In: J. Janick (ed.). Encyclopedia of temperate fruit and nut crops. CABI (in press).

Chen, H., S.A. Mehlenbacher and D.C. Smith. 2007. Hazelnut accessions provide new sources of resistance to eastern filbert blight. HortScience 42 (in press).

Lunde, C.F., S.A. Mehlenbacher and D.C. Smith. 2006. Segregation for resistance to eastern filbert blight in progeny of 'Zimmerman' hazelnut. J. Amer. Soc. Hort. Sci. 131:731-737.

Mehlenbacher, S.A. and D.C. Smith. 2006. Self-compatible seedlings of the cutleaf hazelnut. HortScience 41:482-483.

Mehlenbacher, S.A., R.N. Brown, E.R. Nouhra, T. Gokirmak, N.V. Bassil and T.L. Kubisiak. 2006. A genetic linkage map for hazelnut (Corylus avellana L.) based on RAPD and SSR markers. Genome 49:122-133.

Yezhov, V.N., A.V. Smykov, V.K. Smykov, S.Y. Khokhlov, D.E. Zaurov, S.A. Mehlenbacher, T.J. Molnar, J.C. Goffreda and C.R. Funk. 2005. Genetic resources of temperate and subtropical fruit and nut species at the Nikita Botanical Gardens. HortScience 40:5-9.

Chen, H., S.A. Mehlenbacher and D.C. Smith. 2005. AFLP markers linked to eastern filbert blight resistance from OSU 408.040 hazelnut. J. Amer. Soc. Hort. Sci. 130:412-417.

Boccacci, P., A. Akkak, N.V. Bassil, S.A. Mehlenbacher and R. Botta. 2005. Characterization and evaluation of microsatellite loci in European hazelnut (Corylus avellana L.) and their transferability to other Corylus species. Molec. Ecol. Notes 5:934-937.

Bassil, N.V., R. Botta and S. Mehlenbacher. 2005. Microsatellite markers in hazelnut: Isolation, characterization and cross-species amplification. J. Amer. Soc. Hort. Sci. 130:543-549.

Erdogan, V., S.A. Mehlenbacher, A.I. Köksal and H. Kurt. 2005. Incompatibility alleles expressed in pollen of Turkish hazelnut cultivars. Turkish Journal of Biology 29(2):111-116.

Mehlenbacher, S.A., R.N. Brown, J.W. Davis., H. Chen, N.V. Bassil, D.C. Smith, and T.L. Kubisiak. 2004. RAPD markers linked to eastern filbert blight resistance in Corylus avellana. Theor. Appl. Genet. 108:651-656.

Mehlenbacher, S.A. and D.C. Smith. 2004. Hazelnut pollenizers 'Gamma', 'Delta', 'Epsilon' and 'Zeta'. HortScience 39:1498-1499.

Mehlenbacher, S.A. and M.M. Thompson. 2004. Inheritance of style color in hazelnut. HortScience 39:475-476.

Mehlenbacher, S.A. 2003. Hazelnut. In: D. Fulbright (ed.). A Guide to nut tree culture in North America, Vol. 1. (3rd ed.). Northern Nut Growers Association. p. 182-215.

Fatahi, R., A. Ebadi, N. Bassil, and S.A. Mehlenbacher. 2003. Characterization of Iranian grapevine cultivars using microsatellite markers. Vitis 42:185-192.

Erdogan, V. and S.A. Mehlenbacher. 2002. Phylogenetic analysis of hazelnut species (Corylus, Corylaceae) based on morphology and phenology. OT Sistematik Botanik Dergisi 9(1):83-100.

Mehlenbacher, S.A. and D.C. Smith. 2002. Inheritance of pollen color in hazelnut. Euphytica 127:303-307.

Smith, D.C. and S.A. Mehlenbacher. 2002. 'Rosita' ornamental hazelnut. HortScience 37:1137-1138.

Mehlenbacher, S.A. 2002. Hazelnuts in Georgia and Azerbaijan. Proc. Nut Growers Soc. of Oregon, Wash., and B.C. 87:42-59.

Mehlenbacher, S.A., A.N. Azarenko, D.C. Smith, and R. McCluskey. 2001. 'Clark' hazelnut. HortScience 36:995-996.

Coyne, C.J., S.A. Mehlenbacher, K.B. Johnson, J.N. Pinkerton, and D.C. Smith. 2000. Comparison of two methods to evaluate quantitative resistance to eastern filbert blight in uropean hazelnut. J. Amer. Soc. Hort. Sci. 125:603-608.

Lunde, C.F., S.A. Mehlenbacher, and D.C. Smith. 2000. Survey of hazelnut cultivars for response to eastern filbert blight inoculation. HortScience 35:729-731.

Mehlenbacher, S.A., A.N. Azarenko, D.C. Smith, and R. McCluskey. 2000. 'Lewis' hazelnut. HortScience 35:314-315.

Yao, Q. and S.A. Mehlenbacher. 2000. Heritability, variance components and correlation of morphological and phenological traits in hazelnut. Plant Breeding 119:369-381.

Erdogan, V. and S.A. Mehlenbacher. 2000. Interspecific hybridization in hazelnut (Corylus). J. Amer. Soc. Hort. Sci. 125:489-497. (with figure on cover of issue).

Erdogan, V. and S.A. Mehlenbacher. 2000. Phylogenetic relationships of Corylus species (Betulaceae) based on nuclear ribosomal DNA ITS region and chloroplast matK gene sequences. Systematic Botany 25:727-737.

Osterbauer, N.K., K.B. Johnson, S.A. Mehlenbacher, and T.L. Sawyer. 1997. Analysis of resistance to eastern filbert blight in Corylus avellana. Plant Disease 81:388-394.

Mehlenbacher, S.A. 1997. Revised dominance hierarchy for S-alleles in Corylus avellana L. Theor. Appl. Genet. 94:360-366.

Thompson, M.M., H.B. Lagerstedt, and S.A. Mehlenbacher. 1996. Hazelnuts. p. 125-184. In: J. Janick and J.N. Moore (eds.). Fruit breeding. Vol. 3. Nuts. John Wiley & Sons, New York.

Smith, D.C. and S.A. Mehlenbacher. 1996. Inheritance of contorted growth habit in hazelnut. Euphytica 89:211-213.

Johnson, K.B., S.A. Mehlenbacher, J.K. Stone, J.W. Pscheidt, and J.N. Pinkerton. 1996. Eastern filbert blight of hazelnut: it's becoming a manageable disease. Plant Disease 80:1308-1316.

Coyne, C.J., S.A. Mehlenbacher, R.O. Hampton, J.N. Pinkerton, and K.B. Johnson. 1996. Use of ELISA to rapidly screen hazelnut for resistance to eastern filbert blight. Plant Disease 80:1327-1330.

Mehlenbacher, S.A. 1994. Hazelnut production, processing, and research in Turkey. Proc. Nut Growers Soc. of OR, WA, and BC 79:49-78.

Mehlenbacher, S.A. 1991. Hazelnuts. In: J.N. Moore and J.R. Ballington (eds.). Genetic resources in temperate fruit and nut crops. Acta Hort. 290:789-836.

Professional Experience
EDUCATION:

B.S. in Horticulture, Pennsylvania State University, 1978
Ph.D. in Plant Breeding, Cornell University, 1982

PROFESSIONAL EXPERIENCE:

Oregon Hazelnut Industry Professor, Dept of Horticulture, Oregon State University, 2000-present.
Professor, Department of Horticulture, Oregon State University, 1995-present.
Associate Professor, Department of Horticulture, Oregon State University, 1990-1995.
Assistant Professor, Department of Horticulture, Oregon State University, 1986-1990.
Assistant Professor, Department of Horticulture, Cook College, Rutgers University, 1982-1986.

PRINCIPAL DUTIES:

Research:
Breed new cultivars for Oregon's hazelnut industry, improve breeding methods, document genetic variability in Corylus, develop DNA markers and use them to characterize hazelnut cultivars, identify new sources of disease resistance and use them in breeding, conduct DNA marker-assisted selection for disease resistance, identify incompatibility alleles in hazelnut cultivars and selections.

Teaching:
Teach Plant Breeding (CSS/HORT 450/550) annually.
Teach Breeding Clonal Crops (HORT 505B) in alternate years.
Advise plant breeding graduate students.

Extended Education:
Answer grower questions concerning cultivars and pollinizers, regularly present information on the hazelnut breeding program and activities in other hazelnut-producing countries to grower groups. I continue to receive requests for information from Chile and other countries attempting to establish hazelnut industries.

FUTURE PROGRAM GOALS:

I will continue to develop new hazelnut cultivars for the blanched kernel market with resistance to eastern filbert blight. DNA markers will be used to identify seedlings that carry the 'Gasaway' resistance gene prior to field planting. The response of additional hazelnut accessions to eastern filbert blight inoculation will be assessed, and new sources of resistance used in breeding. Microsatellite loci will be used to "fingerprint" hazelnut cultivars, and the loci will be placed on a linkage map. Map-based cloning of the eastern filbert blight resistance and pollen-stigma incompatibility loci will be initiated using a BAC library. Use hazelnut as a model for genomics studies in the Betulaceae.

MOST SIGNIFICANT SERVICE, PROFESSIONAL ACTIVITIES, AND ACCOMPLISHMENTS (since 1988):

I have visited hazelnut researchers and production areas in many countries, including trips to Georgia, Azerbaijan, Russia, and Iran. I have given presentations in Chile and Argentina where attempts are being made to establish hazelnut industries. Researchers and industry people around the world recognize OSU as the world's leading hazelnut research university. I hosted the Fifth International Congress on Hazelnut in September 2000 and co-edited the proceedings. I regularly review manuscripts for several journals. I have been coordinator of the Horticulture graduate program since Jan. 2004.

GRADUATE STUDENTS ADVISED AS MAJOR PROFESSOR (since 1995):

Kahraman Gurcan (Ph.D., Current) "Development of microsatellite markers for hazelnut".

Sathuvalli Vidyasagar (M.S., Current) "DNA markers for new sources of resistance to eastern filbert blight"

Tufan Gokirmak (M.S., 2005) "Characterization of hazelnut using microsatellite markers"

Honglin Chen (M.S., 2003) "New sources and linked AFLP markers for eastern filbert blight resistance in hazelnut"

Kimberly Bray (M.S. student, withdrew)

China Lunde (M.S., 1999) "Novel sources of genetic resistance to eastern filbert blight in hazelnut"

Veli Erdogan (Ph.D., 1999) "Genetic relationships among hazelnut (Corylus) species"

Qiang Yao (Ph.D., 1998) "Estimation of genetic parameters in the Oregon State University hazelnut (Corylus avellana L.) breeding population"

Joel Davis (M.S., 1998) "Identification and development of PCR based markers linked to eastern filbert blight resistance in hazelnut"

Clarice Coyne (Ph.D., 1995) "Genetic resistance to eastern filbert blight"

Graduate Students Advised in Career: 12 as major professor, 32 as committee member, 16 as grad rep.

PROGRAM SUPPORT (since 1988):

Funds from the State, USDA, Oregon Hazelnut Commission, and Oregon Hazelnut Industry Endowed Professorship provide an annual operating budget of about $230,000.

PARTICIPATION IN MAJOR INTERNATIONAL, NATIONAL, AND REGIONAL MEETINGS (since 1995):

Sixth International Congress on Hazelnut, Tarragona, Spain, June 2004.

Iranian Horticultural Congress, Karaj, Iran, September 2003 (keynote speaker)
International Horticultural Congress, Toronto, Canada, August 2002
Fifth International Congress on Hazelnut, Corvallis, Oregon, August 2000 (host)
Fourth International Congress on Hazelnut, Ordu, Turkey, July-August 1996.
American Society for Horticultural Science annual meetings in Montreal, Quebec; Minneapolis, MN; Toronto, Ontario.

HONORS AND AWARDS:

Oregon Hazelnut Industry Endowed Professorship, 2000 - present.

James and Mildred Oldfield Team Award (for eastern filbert blight research, with plant pathologists K.B. Johnson, J.N. Pinkerton, J.W. Pscheidt, and J.K. Stone), September 1994.

Invited speaker on six occasional at national or international meetings.

PROFESSIONAL AND HONORARY SOCIETY MEMBERSHIPS:

American Pomological Society
American Society for Horticultural Science
Crop Science Society of America
International Society for Horticultural Science

Courses Taught
Plant Breeding (CSS/HORT 450/550) annually
Breeding Clonal Crops (HORT 505B) in alternate years
Advise plant breeding graduate students.