US National Arboretum


Floral and Nursery Plants Research Unit

Dr. Robert J. Griesbach

Research Geneticist
{Beltsville, MD}


CRIS Project Title:  
Genetic Improvement of Floral Crops for Pest, Disease, and Stress Tolerance and Ornamental Qualities

Conducts a broad based research program in the genetics of floral plants. Enhanced germplasm is created from wild species that is disease, insect and stress tolerant. New technologies (i.e., embryo rescue, genetic engineering, molecular markers, etc.) are developed to aid in creating of novel germplasm. Recent research focuses on determining the inheritance of horticulturally valuable traits, such as flower color. The genetics of anthocyanin gene regulation is being studied.

Developed a non-tissue culture system for introducing DNA into the axillary meristem of plants growing in pots. Correlated the biochemical genetics of the flavonoid pathway and the genetics of vacuolar pH with specific flower colors. Determined the evolutionary relationships between Petunia species using the sequence of the chalcone synthase gene intron. Developed a series of Ornithogalum hybrids for potted-plant and cut-flower production that received both US and Australian plant patents.  In cooperation with John Stommel of the Vegetable Laboratory, developed novel peppers for dual use as culinary and ornamental production. One cultivar, ‘Black Pearl’ received the 2006 All-America Selections Award.

To investigate the genetic regulation of tissue-specific anthocyanin gene expression using petunia as a model system. Continue to develop dual use peppers for culinary and ornamental production.


1984. Griesbach, R. An orchid in every pot.  Florists' Rev. 176:26-30.

1984. Griesbach, R. The effects of carotenoid/anthocyanin combinations on flower color.  J. Heredity 75:145-147.

1985. Griesbach, R. Polyploidy in Phalaenopsis orchid improvement. J. Heredity 76:74-75.

1990. Griesbach, R.J. and S. Asen, 1990. Characterization of the flavonol glycosides of Petunia. Plant Science 70:49-56.

1991. Griesbach, R.J., S. Asen and B.A. Leonhardt, 1991. Petunia hybrida anthocyanins acylated with caffeic acid. Phytochemistry 30:1729-1731.

1993. Griesbach, R.J. and T.M. Klein. In situ genetic complementation of a flower color mutant. Lindleyana 8:223-226.

1994. Griesbach, R. J. An improved method for transforming plants through electrophoresis. Plant Science 102:81-89.

1996. Griesbach, R.J. The inheritance of flower color in Petunia hybrida. J. Heredity 87:241-245.

1997.  Griesbach, R.J. The biochemical basis for the blue flower color mutations in Doritis pulcherrima and Phalaenopsis violacea. Lindleyana 12:64-71.

1998.  Griesbach, R.J.  The affect of the Ph 6 gene on the color of Petunia hybrida flowers.  J. Amer. Soc. Hort. Sci. 123:647-650.

1998.  Griesbach, R.J. and F. Meyer, 1998. Three new cultivars of Ornithogalum: 'Chesapeake Blaze', 'Chesapeake Sunset' and 'Chesapeake Sunshine'. HortScience 33:345-347.

2002. Griesbach, R.J. Inheritance of the An2 gene and epistatic interactions in Petunia exserta x P. axillaries hybrids. J. Amer. Soc. Hort. Sci. 127:947-956.

2003. Griesbach, R.J. and F.S. Santamour, Jr. Anthocyanins in cones of Abies, Picea, Pinus, Pseudotsuga, and Tsuga (Pinaceae). Biochem. System. Ecol. 31:261-268.

2003. Farzad, M., R. Griesbach, J. Hammond, M. Weiss and H. Elmendorf. Differential expression of three key anthocyanin biosynthetic genes in a color-changing flower, Viola cornuta cv. Yesterday, Today and Tomorrow. Plant Science165:1333-1342.

2004. Freyre, R. and R.J. Griesbach. Inheritance of flower color in Anagallis monelli L. HortScience 39:1220-1223.

2005. Griesbach, R.J. Biochemistry and genetics of flower color. Plant Breed. Rev. 25:89-114.

2005. Griesbach, R.J. and Beck, R.M. Sequence analysis of the chalcone synthase gene in four Petunia taxa. J. Amer. Soc. Hort. Sci. 130:360-365.

2005. Stommel, J.R. and Griesbach, R.J. Capsicum annum L. 'Black Pearl'.  HortScience 40:1571-1573.

2005. Griesbach, R.J. Petunia x hybrida. In: Flower Breeding and Genetics, ed. N.O. Anderson. Kluwer Press, Netherlands. p. 292-328.

2005. Griesbach, R.J. and S. Austin. Comparison of the Munsell and Royal Horticultural Society’s color charts in describing flower color. Taxon 54:771-773.


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