Ryan Warner

Ryan Warner

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Associate Professor
Department of Horticulture

(517) 353-0344


Quick links: Education    Publications    Research

Joined Department

September 1, 2004


75% Research

25% Teaching


Ph.D., Applied Plant Sciences, University of Minnesota, 2004

M.S., Horticultural Science, University of Minnesota, 1999

B.S., Horticulture, Michigan State University, 1996

Graduate Programs

Plant Breeding, Genetics and Biotechnology


Genetic Determinants of Crop Development and Quality

Being sessile organisms, plants are often subjected to suboptimal or supraoptimal environmental conditions, including temperature, light intensity, and water availability. These environmental variables influence crop timing and quality. My lab is broadly interested in understanding the genetic control of these traits, with a particular emphasis on how development rate during the vegetative phase is controlled, including the temperature sensitivity of this process.

The rate at which plants produce new nodes (development rate) is a fundamental biological process that impacts agriculture through control of crop timing and biomass accumulation. The long-term goal of this project is to elucidate the genetic determinants of plant development rate and utilize this knowledge to facilitate breeding of superior agricultural crop varieties. Unfortunately, the genetic control of development rate is poorly understood. My lab is utilizing genomics, QTL mapping, and differential gene expression analysis between fast- and slow-developing recombinant inbred lines from an interspecific Petunia population to identify and functionally characterize candidate genes putatively involved in control of this developmental process.

Breeding and Genetics of Stevia

Stevia rebaudiana (stevia) is a rapidly emerging new crop in the U.S. and worldwide, grown for the extraction of sweet-tasting steviol glycosides used as natural non-caloric sweeteners in food and beverage applications. My lab is breeding new varieties of stevia with an emphasis on improving production of steviol glycosides with a superior taste profile to what is currently available. Additionally, we are developing genetic and genomic resources to facilitate understanding of traits important for agricultural production and steviol glycoside biosynthesis.


Vallejo VA, Warner RM (2021) Identifying quantitative trait loci for steviol glycoside production in Stevia rebaudiana using transcriptome-derived SSRs. Industrial Crops and Products 161:113176 

Guo, Y., Warner, R.M. (2020) Dissecting genetic diversity and genomic background of Petunia cultivars with contrasting growth habits. Horticulture Research 7:155

Warner RM (2020) Differential temperature sensitivity of flowering time and crop quality parameters of 20 seed-propagated petunia cultivars. HortScience 55:362-367

Chen QC, Guo Y, Warner RM. (2019) Mapping quantitative trait loci for component traits of flowering capacity across temperature in an interspecific Petunia recombinant inbred line population. G3: Genes, Genomes, Genetics 9:3601-3610

Cao Z, Guo Y, Yang Q, He Y, Fetouh M, Warner RM, Deng Z. (2019) Genome-wide identification of quantitative trait loci for important plant and flower traits in petunia using a high-density linkage map and an interspecific recombinant inbred population derived from Petunia integrifolia and P. axillarisHorticulture Research 6:27

Cao Z, Guo Y, Yang Q, He Y, Fetouh M, Warner RM, Deng Z. (2018) Genome-wide search for quantitative trait loci controlling important plant and flower traits in petunia using an interspecific recombinant inbred line population of Petunia axillaris and Petunia exsertaG3: Genes, Genomes, Genetics 8:2309-2317

Guo, Y., Lin W.-K., Chen Q., Vallejo V.A., Warner R.M. (2017) Genetic determinants of crop timing and quality traits in two interspecific Petunia recombinant inbred line populations. Scientific Reports 7:3200. 

Bombarely, A., M. Moser, A. Amrad, M. Bao, L. Bapaume, C. S. Barry, …, R.M. Warner, et al. (2016). Insight into the evolution of the Solanaceae from the parental genomes of Petunia hybrida. Nature Plants 2: 16074

Guo, Y., Wiegert-Rininger, K., Vallejo, V. A., Barry, C. S., Warner, R.M. (2015) Transcriptome-enabled marker discovery and mapping of plastochron-related genes in Petunia spp. BMC Genomics, 16:726. 

Vallejo V.A., Tychonievich J., Lin W.-K., Wangchu L., Barry C.S., Warner R.M. (2015) Identification of QTL for crop timing and quality traits in an interspecific Petunia population. Mol. Breed. 35:2 DOI 10.1007/s11032-015-0218-4.  

Evans, J.M., Vallejo, V.A., Beaudry, R.M., Warner, R.M. (2015) Daily light integral influences steviol glycoside biosynthesis and relative abundance of specific glycosides in stevia. HortScience 50:1479-1485. 

Walworth, A.E., G.-Q. Song and R.M. Warner (2014). Ectopic AtCBF3 expression improves freezing tolerance and promotes compact growth habit in petunia. Mol. Breed. 33:731-741 DOI 10.1007/s11032-013-9989-7 

Tychonievich, J., L. Wangchu, C. Barry and R.M. Warner (2013). Utilizing wild species for marker-assisted selection of crop timing and quality traits in Petunia. Acta Hortic. 1000:465-470.

Shafii, B., Vismeh, R., Beaudry, R., Warner, R. and Jones, A.D. (2012). Large-scale profiling of diterpenoid glycosides from Stevia rebaudiana using ultrahigh performance liquid chromatography/tandem mass spectrometry. Anal. and Bioanal. Chem. 403:2683-90.

Tychonievich, J. and R.M. Warner (2011) Interspecific crossability of selected Salvia spp. and potential utility for crop improvement. J. Amer. Soc. Hort. Sci.  136:41-47.

Warner, R.M. and A.E. Walworth (2010). Quantitative inheritance of crop timing traits in interspecific hybrid Petunia populations and interactions with crop quality parameters. J. Hered. doi: 10.1093/jhered.esp131 (pdf)

Bradford, E., J.F. Hancock and R.M. Warner (2010). Interactions of temperature and photoperiod determine expression of repeat flowering in strawberry. J. Amer. Soc. Hort. Sci. 135:102-107.

Warner, R.M. (2010). Temperature and photoperiod influence flowering and morphology of four Petunia spp. HortScience 45:365-368.

Stegmeir, T.L., C.E. Finn, R. M. Warner and J.F. Hancock (2010). Performance of an elite strawberry population derived from wild germplasm of Fragaria chiloensis and F. virginiana. HortScience 45:1140-1145.

Oh, W., E. Runkle and R. Warner (2010). Timing and duration of supplemental lighting during the seedling stage influence quality and subsequent flowering in petunia and pansy. HortScience 45: 1332-1337.