Ryan Contreras

Ryan Contreras

Associate Professor, Ornamental Plant Breeding
ryan.contreras [at] oregonstate.edu

Office: 541-737-5462
Other: ryan.contreras@oregonstate.edu
Fax: 541-737-3479

My teaching and research focuses on woody nursery and landscape plants. I teach spring and fall woody plant identification courses, growth and development of horticultural crops, and plant propagation. Research in my lab is closely aligned with the nursery industry to try and develop new plants that work well in production and serve the needs of growers and gardners alike. As the nursery industry grows an incredible diversity of crops, we try to address a diverse suite of plants from low growing shrubs or groundcovers to large shade trees. This interest in serving the needs of the industry has led me to intitiate projects on nearly 50 genera.

Research

My research program involves several areas of ornamental plant breeding and cultivar development. Of primary interest is the development of sterile forms of nonnative species that are of economic importance to Oregon growers to prevent escape from cultivation. Primary techniques to achieve sterility/reduced fertility include develoment of triploids using ploidy manipulation, as well as mutagenesis by exposing seeds or meristems to physical and chemical mutagens.

My lab conducts fundamental research in traditional genetics, cytogenetics, molecular genetics, and genomics to support the applied breeding program with the goal of developing plants that are attractive to consumers, easy for growers to produce, and resilient in modern landscapes. The end goal is to develop new cultivars that have increased insect and disease resistance combined with superior aesthetics.

Teaching

HORT 226. Landscape Plant Materials I: Deciduous Hardwoods and Conifers. Fall. 4 credits
HORT 226e. Landscape Plant Materials I: Deciduous Hardwoods and Conifers. Fall - Online. 4 credits
HORT 228. Landscape Plant Materials II: Spring Flowering Trees and Shrubs. Spring. 4 credits
HORT 228e. Landscape Plant Materials II: Spring Flowering Trees and Shrubs. Spring - Online. 4 credits
HORT 301. Growth and Development of Horticutural Crops. Fall. 3 credits
HORT 301e. Growth and Development of Horticutural Crops. Fall & Spring - Online. 3 credits
HORT 310e. Principles of Plant Propagation. Winter - Online. 3 credits
HORT 311. Plant Propagation. Winter. 4 credits

Team Members

Project Leader - Ryan Contreras

Education

Ph.D. Horticulture, The University of Georgia - 2009
M.S. Horticultural Science, North Carolina State University - 2006
B.S. Horticultural Science, North Carolina State University - 2002.

Appointments

Associate Professor, Oregon State University, Department of Horticulture. 40% Teaching / 55% Research. September 2016 - current.
Assistant Professor, Oregon State University, Department of Horticulture. 40% Teaching / 35% Research. December 2009 - September 2016
Graduate Research Assistant, University of Georgia, Athens, Georgia, Department of Horticulture. 2006 - 2009
Graduate Research Assistant, North Carolina State University, Raleigh, Department of Horticultural Science. 2004 - 2006

Awards and Honors

2020 American Society for Horticultural Science - Research Division Vice President-Elect
2019 Oregon Association of Nurseries President’s Five Star Award
2018 Oregon Association of Nurseries Distinguished Education Award
2018 Western Region Award for Excellence in College and University Teaching in the Food and Agricultural Sciences
2016 Oregon Association of Nurseries President’s Five Star Award
2015 R.M. Wade Award for Excellence in Teaching and Registry of Distinguished Teachers
2013 College of Agricultural Sciences Savery Outstanding Young Faculty Award

Research Assistant - Tyler Hoskins

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Tyler is a native Oregonian who has degrees from Clackamas Community College, George Fox, and Virginia Tech. The latter is where he honed his expertise in managing water and nutrients in soilless substrates of nursery crops - earning his M.S. with former Oregon State professor, Jim Owen. Tyler expertly manages the growing operation for the breeding program from propagation, to containers, field production, irrigation, and fertilization.

Current Graduate Students

Adigun McLeod: Ploidy manipulation of different lines of industrial hemp

Cara Still: Reproductive behavior and pollinator attraction of Buddleja cultivars

Sunny Green: Pollen analysis and crossability of Vaccinium

Dan Blanchard: Developing mapping and database tools for the Oregon State University landscape

Past Students

Kristin Neill - M.S. 2020 - Phenotyping Ornamental Plants: Case Studies in Disease Resistance of Cotoneaster and Fruit Quality Attributes from Vaccinium ovatum. Current Position: Family Tree Nursery, Kansas City, MO.
Hsuan Chen - Ph.D. 2018 - Developing Tools for Hardy Hibiscus and Lilac Breeding: Quantile Regression, Cytogenetics, Interspecific Hybridization, Somatic Hybridization, and Marker-Trait Association. Current Position: Plant Breeder at Jack Hempicine, LLC. Oregon.
Jason Lattier - Ph.D. 2017 - Breeding and Genetics of Lilacs and Hardy Hibiscus. Current Position: Director and Curator Caine Conservatory, High Point University, North Carolina.
Justin Schulze - M.S. 2017 - Breeding, Production, and Morphophysiology among Cytotypes of Common and Portuguese Cherrylaurel. Current Position: Plant Breeder and Horticulturist with Bailey Nurseries, Inc. at their PII location in Watkinsville, GA.
Kim Shearer - M.S. 2016 - Inducing and evaluating phenotypic and cytometric variation in landscape plants: Observations from Acer, Galtonia, and Penstemon. Current Position: Tree and Shrub Breeder at the Morton Arboretum, Chicago, IL.
Joseph Rothleutner - M.S. 2012 - Genome Sizing and Fire Blight Resistance Screening in Cotoneaster. Current Position: Director of Horticulture at the Lincoln Park Zoo, Chicago, IL

Undergraduate Researchers and Interns

Current

Madelaina DiPasquale. Phenology and propagation of Camellia grown in Corvallis, OR.
Ethan Cottel. Mutation of Euonymus japonicus and Photinia serratifiolia

Past

Josh Ashcraft. Phenology of the maple germplasm collection including synthetic polyploids at OSU Ornamental Plant Breeding
Ty Seely. Analysis of pollen from 22x, 33x, 44x, and 22x+44x common cherrylaurels.
Patrice Woodworth. Ploidy analysis of seedlings dervied from 4x Acer ginnala & Acer platanoides and 2x+4x Hydrangea macrophylla.
Gwyn Alanko: Ploidy analysis of maple seedlings derived from tetraploid parents.
Sawyer Hurd: Intern and assistant on mockorange breeding to evaluate fragrance, flowering, and form among newly developed hybrids
Jon Dempster: Fertility and morphological observations of 2x, 3x, and 4x crabapples including 'Prairiefire' and its polyploid derivatives.
Aleen Haddad: Genome size analysis in Acer: Comparing methods of sample handling and preparation
Rebecca Reeve: In vivo polyploidization of Hibiscus syriacus using diffferent mitotic inhibitors and application techniques
Geena Quinones: Non-targeted mutagenesis of Carpenteria californica using varying rates of gamma radiation
Morgan Chan: Field evaluation and herbarium voucher collection for 49 species of Cotoneaster
Tucker Doyle: In situ chromosome doubling of four Oregon native plants of varying growth forms
Tiffany Pham: In vitro polyploidization of Hydrangea macrophylla
Keith Lukowski: Mapping the woody flora of Oregon State University
Coral Cummings: Viability and longevity of Prunus laurocerasus and P. lusitanica pollen under varying storage conditions
Imogene Hollis: Propagation and cataloguing newly received accessions for the Ornamental Plant Breeding Program

Cultivar Releases

Ribes sanguineum 'Oregon Snowflake' PP26763

Cotoneaster ×suecicus 'Emerald Sprite' PP31,719

Cotoneaster ×suecicus 'Emerald Beauty' PP32,308

Publications (*indicates student author)

2020

Contreras, R.N. and T.C. Hoskins. 2020. Developing triploid maples. Horticulturae 6(4)70. https://doi.org/10.3390/horticulturae6040070

Hoskins, T.C., *J.D. Lattier, and R.N. Contreras. 2020. Sowing green seed without stratification does not shorten juvenility or increase plant size in common lilac (Syringa vulgaris). HortScience 55(11):1781-1787. https://doi.org/10.21273/HORTSCI15328-20

*Lattier, J.D. and R.N. Contreras. 2020. Segregation of flower color and eyespot in althea. J. Amer. Soc. Hort. Sci. 145(4):215-227 https://doi.org/10.21273/JASHS04824-19.

Contreras, R.N. and *Shearer, K. 2020. Exposing seeds of Galtonia candicans to ethyl methanesulfonate (EMS) reduced inflorescence height, lodging, and fertility. HortScience 55(5):621-624 https://doi.org/10.21273/HORTSCI14775-19.

*Chen, H., J.D. Lattier, K. Vining, and R.N. Contreras. 2020. Two SNP markers identified using GBS are associated with remontancy in a segregating F1 population of Syringa meyeri ‘Palibin’ x S. pubescens ‘Penda’ Bloomerang®. J. Amer. Soc. Hort. Sci. 145(2):104-109 https://doi.org/10.21273/JASHS04847-20.

*Petter, J., P. Ries, A. D’Antonio, and R.N. Contreras. 2020. A Tree Selection Survey of Tree City USA Designated Cities in the Pacific Northwest. Arboriculture & Urban Forestry. (in press).

*Petter, J., P. Ries, A. D’Antonio, and R.N. Contreras. 2020. How are managers making tree species selection decisions in the Pacific Northwest of the United States? Arboriculture & Urban Forestry. 46(2):148-161.

2019

Hoskins, T. and R.N. Contreras. 2020. Exposing seeds of Sarcococca confusa to increased concentrations and durations of ethyl methanesulfonate reduced seed germination, twinning, and plant size. HortScience 54(11):1902-1906. https://doi.org/10.21273/HORTSCI14428-19

Graebner, R.C., H. Chen, R.N. Contreras, K.G. Haynes, and V.R. Sathuvalli. 2019. Identication of a high frequency of triploid potatoes from tetraploid x diploid crosses. HortScience 54(7)1159-1163.

*Lattier, J.D., H. Chen, and R.N. Contreras. 2019. Variation in genome size, ploidy, stomata, and rDNA signals in althea (Hibiscus syriacus L.). J. Amer. Soc. Hort. Sci. 144(2):130-140.

Vining, K.J., I. Pandelova, K. Hummer, N. Bassil, R.N. Contreras, K. Neill, H. Chen, A.N. Parrish, and B.M. Lange. Genetic diversity survey of Mentha aquatica L. and Mentha suaveolens Ehrh., mint crop ancestors. Genetic Resources and Crop Evolution 66(4):825-845.

*Chen, H., L. Xue, T. Li, and R.N. Contreras. 2019. Quantile regression facilitates simultaneous selection of negatively correlated floral traits among BC₁F₁ progeny of the male fertile hybrid cultivars Lohengrin and Resi (Hibiscus syriacus x H. paramutabilis). J. Amer. Soc. Hort. Sci. 144(1):70-76.

2018

Contreras, R.N. and K. Shearer. 2018. Genome size, ploidy, and base composition of wild and cultivated Acer. J. Amer. Soc. Hort. Sci. 143(6):470-485. https://doi.org/10.21273/JASHS04541-18

2017

*Lattier, J.D. and R.N. Contreras. 2017. Ploidy and genome size in lilac species, cultivars, and interploid hybrids. J. Amer. Soc. Hort. Sci. 142(5):355–366. doi: 10.21273/JASHS04189-17

*Lattier, J.D. and R.N. Contreras. 2017. Intraspecific, interspecific, and interseries cross-compatibility in lilac. J. Amer. Soc. Hort. Sci. 142(4):279-288. (JASHS cover).

*Lattier, J.D., H. Chen, and R.N. Contreras. 2017. Improved method for enzyme digestion of root tips for cytology. HortScience 52(7):1029-1032.

*Schulze, J.A., J.D. Lattier, and R.N. Contreras. 2017. In vitro germination of immature Prunus lusitanica seed. HortScience 52(8):1122-1124.

*Schulze, J.A. and R.N. Contreras. 2017. In vivo chromosome doubling of Prunus lusitanica and preliminary morphological observations. HortScience. 52(3):332-337.

*Schulze, J.A., R.N. Contreras, and C.F. Scagel. 2017. Comparing vegetative propagation of two ‘Schipkaensis’ cherrylaurel ploidy levels. HortTechnology 27(1):69-72.

2016

Contreras, R.N. and L. Meneghelli. 2016. In vitro chromosome doubling of Prunus laurocerasus 'Otto Luyken' and 'Schipkaensis'. HortScience 51(12):1463-1466.

*Rothleutner, J.J., M.W. Friddle, and R.N. Contreras. 2016. Ploidy levels, relative genome sizes, and base pair composition in Cotoneaster. J. Amer. Soc. Hort. Sci. 141(5):457-466.

Schwartz, B.M., R.N. Contreras, K.R. Harris-Schultz, D.L. Heckart, J.B. Peake, and P.L. Raymer. 2013. Discovery and characterization of a turf-type triploid seashore paspalum. HortScience 48(12):1424-1427.

Schwartz, B.M., K.R. Harris-Schultz, R.N. Contreras, C.S. Hans, W.W. Hanna, and S.R. Milla-Lewis. 2013. Creation of artificial triploid and tetraploid centipedegrass using colchicine and breeding. Intl. Turfgrass Soc. Res. J. 12:327-334.

Contreras, R.N., J.S. Owen, W.W. Hanna, and B.M. Schwartz. 2013. Evaluation of seven complex Pennisetum spp. hybrids for container and landscape performance in the Pacific Northwest. HortTechnology 23(4):525-528.

Schwartz, B.M., K.R. Harris-Schultz, C.S. Hans, R.N. Contreras, and S.A. Jackson. 2013. Creation of hexaploid and octoploid zoysiagrass using colchicine and breeding. Crop Science 53:2218-2224.

Landgren, C., J.S. Owen, and R.N. Contreras. 2013. Evaluating soil and foliar fertilization of Abies nordmanniana under container and field production. Scandinavian J. For. Res. Published online 7 Jan 2013. doi:10.1080/02827581.2012.762939

Contreras, R.N., R. Golembiewski, J. Velez. 2013. Evaluation of study habits of plant identification students. HortTechnology 23(1):130-133.

2012

Vining, K.J., R.N. Contreras, M. Ranik, and S.H. Strauss. 2012. Genetic methods for mitigating invasiveness of woody ornamental plants: research needs and opportunities. HortScience 47(9):1210-1216.

Contreras, R.N. 2012. A simple chromosome doubling technique is effective in several species of Cupressaceae. HortScience 47(6):712-714.

Contreras, R.N., J.M. Ruter, J. Conner, Y. Zeng, and P. Ozias-Akins. 2012. Interspecific hybridization in Tecoma Juss. (Bignoniaceae): Confirmation of hybridity using GISH and determination of 18s rDNA copy number using FISH in F₁ hybrids. Genome 55(6):437-445. doi: 10.1139/g2012-030

2011

Contreras, R.N., R. Determann, and M. Friddle. 2011. Differences in winter browning among japanese-cedar cultivars are not due to variation in ploidy levels. HortScience 46(11):1465-1467.

Contreras, R.N. and J.M. Ruter. 2011. Genome size estimates and chromosome numbers of Callicarpa L. (Lamiaceae). HortScience 46(4):567-570.

2010

Contreras, R.N., J.M. Ruter, and B.M. Schwartz. 2010. Oryzalin-induced tetraploidy in Cryptomeria japonica (Cupressaceae). HortScience 45(2):316-319.

2009

Contreras, R.N., J.M. Ruter, and W.W. Hanna. 2009. An oryzalin-induced autoallooctoploid of Hibiscus acetosella Welw. ex Hiern. ‘Panama Red’ (Malvaceae). J. Amer. Soc. Hort. Sci. 134(5):553-559.

Contreras, R.N. and J.M. Ruter. 2009. Sulfuric acid scarification of Callicarpa americana (Lamiaceae) seeds improves germination. Native Plants J. 10(3):283-286.

2008

Contreras, R.N. and T.G. Ranney. 2008. New opportunities for breeding fragrant rhododendrons. J. Amer. Rhododendron Soc. 62(4):201-202.

2007

Contreras, R.N., T.G. Ranney, S.R. Milla-Lewis, and G.C. Yencho. 2007. Investigating parentage and hybridity of three azaleodendrons using amplified fragment length polymorphism analysis. HortScience 42(3):740-743. https://doi.org/10.21273/HORTSCI.42.3.740

Contreras, R.N., T.G. Ranney, and S.P. Tallury. Reproductive behavior of diploid and allotetraploid Rhododendron L. ‘Fragrant Affinity’. 2007. HortScience 42(1):31-34.

Curriculum Vitae: