Research

 

Research Interests:

Determining the consequences of the implementation of genetically modified (GM) crops into agriculture has been one focus in my research. I have studied the effects of hybridization and transgene movement from GM crops to their wild relatives using a Brassica model system. Future research will expand on current work (see publications below), and explore the consequences of crop gene introgression into the genetic backgrounds of weed species.

The enabling tool in my research has been the use of green fluorescent protein (GFP) as a marker for fitness enhancing transgenes, such as the Bt insecticidal protein. I am continuing my interest in the expression of transgene marker technologies, and am currently involved in the development of the transgenic systems for educational purposes.  The use of novel GFP transgenic Arabidopsis in college-level genetics laboratory exercises allows students to explore Mendelian genetics and biotechnology in a single semester-long project.
 

 

GFP canola (left) with a wild-type plant (right) under UV light.

Theoretical and Applied Genetics (2001, 103:659-667)

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Book Chapters:

Abercrombie, JM, Halfhill, MD, Stewart, CN, Jr. (2005) Transgenic plants for environmental monitoring and extraction of arsenic. In: Genetic Resources and Biotechnology, Volume Three.  Thangadurai, D, Pullaiah, T, Tripathy, L (Eds), Regency Publications, New Delhi, India.  143-152.

Rao, MR, Halfhill, MD, Stewart, CN, Jr. (2005) Phytosensing and phytoremediation: a plant approach to locate and eliminate contamination due to explosive chemicals.  In: Genetic Resources and Biotechnology, Volume Three.  Thangadurai, D, Pullaiah, T, Tripathy, L (Eds), Regency Publications, New Delhi, India.  134-142.

Halfhill, MD, Warwick, SI, Stewart, CN, Jr. (2004). Transgene expression and genetic introgression associated with the hybridization of GFP transgenic canola (Brassica napus L.) and wild accessions of bird rape (Brassica rapa L.). In: Introgression from Genetically Modified Plants into Wild Relatives. den Nijs, HCM, Bartsch, D, Sweet, J (Eds), CAB International, Oxfordshire, UK.

Halfhill, MD, Millwood, RJ, Stewart, CN, Jr. (2004). GFP quantification in whole plants. In: Methods in Molecular Biology: Green Fluorescent Protein: Applications and Protocols. Hicks, BW (Ed.), Humana Publishing. Totowa, NJ. 215-225.

Hudson, LC, Halfhill, MD, Stewart, CN, Jr. (2004). Transgene dispersal through pollen. In: Methods in Molecular Biology: Green Fluorescent Protein: Applications and Protocols. BW. Hicks, (Ed.), Humana Publishing. Totowa, NJ. 365-374.

Richards, HA, Hudson, LC, Halfhill, MD, Stewart, CN, Jr. (2004). Genetically modified controversies: sensational headlines versus pragmatic research. In: Plant Tissue Culture and Development. Trigiano, RN and Gray, DJ (Eds). CRC Press, LLC, Boca Raton, FL. (in press).

Stewart, CN, Jr., Halfhill, MD, Millwood, RJ (2002). Green fluorescent protein in transgenic plants: Brassica transformation. In: Methods in Molecular Biology, vol. 183: Green Fluorescent Protein: Applications and Protocols. Hicks, BW (Ed.), Humana Publishing. Totowa, NJ. 245-252.

Millwood, RJ, Halfhill, MD, and Stewart, CN, Jr. (2001). Visualization of GFP transgenic plant cells from undifferentiated tissue to shoots, GFP in Motion II CD. Supplement to Trends in Cell Biology.

Stewart, CN, Jr., Halfhill, MD, and Richards, HA (2000). GFP in plant biotechnology and agriculture. In: Proceeding of the 11th International Symposium on Bioluminescence & Chemiluminescence. Case, JF, Herring, PJ, Robison, BH, Haddock, SHD, Kricka, LJ, Stanley, PE (Eds.), World Science.
 

Articles:

Halfhill, MD, Good, LL, Basu, C, Burris, J, Main, CL, Mueller, TC, Stewart, CN, Jr. (2007)  Transformation and segregation of GFP fluorescence and glyphosate resistance in  horseweed (Conyza canadensis) hybrids.  Plant Cell Reports, 26:303-311.

Moon, HS, Halfhill, MD, Good, LL, Raymer, PL, Stewart, CN, Jr.  (2007) Characterization of directly transformed weedy Brassica rapa and introgressed B. rapa with Bt cry1Ac and gfp transgenes. Plant Cell Reports, 26-1001-1010.

Moon, HS, Halfhill, MD, Hudson, LC, Stewart, CN, Jr. (2006)  Expression of green fluorescent protein (GFP) in pollen of oilseed rape (Brassica napus L.) and its utility for assessing pollen movement in the field.  Biotechnology Journal, 1:1147-1152.

Halfhill, MD, Sutherland, JP, Moon, HS, Poppy, GM, Warwick, SI, Weissinger, AK, Rufty, TW, Raymer, PL, Stewart, CN, Jr. (2005) Growth, productivity, and competitiveness of introgressed weedy Brassica rapa hybrids selected for the presence of Bt cry1Ac and gfp transgenes.  Molecular Ecology, 14:3177-3189.

Stewart, CN, Jr., Millwood, RJ, Halfhill, MD, Ayalew, M, Cardoza, V, Kooshki, M, Capelle, GA, Kyle, KR, Piaseki, D, McCrum, G, Di Benedetto, J. (2005) Laser-induced fluorescent imaging and spectroscopy of GFP transgenic plants. Journal of Fluorescence, 15:697-705.

Basu, C, Halfhill, MD, Mueller, TC, Stewart, CN, Jr. (2004) Weed Genomics: new tools to understand weed biology.  Trends in Plant Science, 9:391-398.

Halfhill, MD, Zhu, B, Warwick, SI, Raymer, PL, Millwood, RJ, Weissinger, AK, Stewart, CN, Jr. (2004) Hybridization and backcrossing between transgenic oilseed rape and two related weed species under field conditions. Environmental Biosafety Research, 3:1-9.

Zhu, B, Lawrence, JR, Warwick, SI, Mason, P, Braun, L, Halfhill, MD, and Stewart, CN, Jr. (2004). Fate of transgenes from transgenic GFP-Bt Brassica napus to wild B. rapa accessions. Environmental Biosafety Research, 3:45-54.

Zhu, B, Lawrence, JR, Warwick, SI, Mason, P, Braun, L, Halfhill, MD, and Stewart, CN, Jr. (2003). Stable Bacillus thuringiensis (Bt) toxin content in interspecific F1 and backcross populations of wild Brassica rapa after Bt gene transfer. Molecular Ecology, 13:237-241.

Halfhill, MD, Millwood, RJ, Weissinger, AK, Warwick, SI, and Stewart, CN, Jr. (2003). Additive transgene expression and genetic introgression in multiple GFP transgenic crop x weed hybrid generations. Theoretical and Applied Genetics, 107:1533-1540.

Halfhill, MD, Millwood, RJ, Rufty, TW, Weissinger, AK, and Stewart, CN, Jr. (2003). Spatial and temporal patterns of green fluorescent protein (GFP) fluorescence during leaf canopy development in transgenic oilseed rape, Brassica napus L. Plant Cell Reports, 22:338-343.

Stewart, CN, Jr., Halfhill, MD, Warwick, SI (2003). Transgene introgression from genetically modified crops to their wild relatives. Nature Reviews Genetics, 4:806-817.

Millwood, RJ, Halfhill, MD, Harkins, D, Russotti, R, and Stewart, CN, Jr. (2003). In vivo measurements of GFP in plants: the effectiveness of a portable spectrofluorometer. BioTechniques, 34:638-643.

Richards, HA, Halfhill, MD, Millwood, RJ, Stewart, CN, Jr. (2003). Quantitative GFP fluorescence as an indicator of recombinant protein synthesis in transgenic plants. Plant Cell Reports, 22:117-121.

Halfhill, MD, Millwood, RJ, Raymer, PL, Stewart, CN, Jr. (2002). Bt transgenic oilseed rape hybridization with its weedy relative, Brassica rapa. Environmental Biosafety Research, 1:19-28.

Halfhill, MD, Richards, HA, Mabon, and Stewart, CN, Jr. (2001). Expression of GFP and Bt transgenes in Brassica napus and hybridization with Brassica rapa. Theoretical and Applied Genetics, 103:659-667.

Stewart, CN, Jr., Richards, HA, and Halfhill, MD (2000). Transgenic plants and biosafety: science, misconceptions, and public perceptions. BioTechniques, 29:832-843.

Harper, BK, Mabon, SA, Leffel, SM, Halfhill, MD, Richards, HA, Moyer, KA, and Stewart, CN, Jr. (1999). Green fluorescent protein as a marker for expression of a second gene in transgenic plants. Nature Biotechnology, 17:1125-1129.

Dolan, RW, Yahr, R, Menges, ES, and Halfhill, MD (1999). Conservation implications of genetic variation in three rare species endemic to Florida rosemary scrub. American Journal of Botany, 86:1556-1562.