Associate Professor of Plant Biology
Ph.D. (1999) University of Georgia

Phone: 706-583-5511
Email: jmburke@plantbio.uga.edu

Research in the Burke Lab

Broadly speaking, we study plant evolutionary genetics. We're currently engaged in population and quantitative genetic analyses of evolutionary divergence in two genera (Helianthus and Stephanomeria) within the Asteraceae (a.k.a. the Compositae, or sunflower family). We also maintain an interest in the ecological impact of transgene escape from genetically modified crops into their wild relatives.

Lab Members

Awards

 

Research Interests

The Genetics of Domestication - The domestication of crop plants typically involves rapid and dramatic phenotypic evolution in response to strong selection. Research in our lab is aimed at understanding the genetic basis of such evolutionary transitions using sunflower (Helianthus annuus) as a model system. We are taking a genetic map-based approach in order to localize regions of the genome that harbor genes controlling domestication-related traits. We are also hunting for genes that bear the population genetic 'signature of selection,' as such genes are especially likely to be of evolutionary and agronomic interest.

Reducing the Risks of Transgene Escape - The commercial introduction of genetically modified crop plants makes possible the evolution of increasingly weedy or invasive wild plants (so-called "superweeds") following transgene escape via hybridization. A number of methods of mitigating the risks associated with transgene escape have been proposed. We are investigating the utility of one such strategy: the placement of transgenes in close proximity to genes at which the cultivar alleles are negatively selected in the wild. Assuming that such genes are sufficiently negatively selected, they should offset the advantages provided by a given transgene, thus slowing (or stopping) its spread.

The Genetics of Speciation - The genus Stephanomeria contains two especially interesting cases of speciation. The first is the derivation of S. malheurensis from S. exigua. This speciation event seemingly occurred in sympatry, running counter to the classical view of how species form. The second involves the origin of S. diegensis, which is a diploid hybrid species formed following hybridization between S. exigua and S. virgata. We are currently developing the molecular tools necessary to map the genomes of these species as part of our ongoing efforts to: (1) investigate patterns of chromosomal evolution across the genus, and (2) genetically map the reproductive barriers distinguishing these species.

Selected Publications

Pashley, C.H., J.R. Ellis, D.E. McCauley, and J.M. Burke. 2006. EST databases as a source for molecular markers: lessons from Helianthus. J. Hered., in press.

Wills, D.M. and J.M. Burke. 2006. Chloroplast DNA variation confirms a single origin of domesticated sunflower (Helianthus annuus L.). J. Hered., in press.

Ellis, J.R., C.H. Pashley, J.M. Burke, and D.E. McCauley. 2006. High genetic diversity in a rare and endangered sunflower as compared to a common congener. Mol. Ecol., in press.

Liu, A. and J.M. Burke. 2006. Patterns of nucleotide diversity in wild and cultivated sunflower. Genetics 173: 321-330.

Chapman, M.A. and J.M. Burke. 2006. Letting the gene out of the bottle: the population genetics of GM crops. New Phytol. (Tansley Review) 170: 429-443.

Arnold, M.L. and J.M. Burke. 2006. Natural hybridization. In C.W. Fox and J.B. Wolf, eds. Pp. 399-413 in Evolutionary Genetics: Concepts and Case Studies. Oxford University Press.

Burke, J.M., S.J. Knapp, and L.H. Rieseberg. 2005. Genetic consequences of selection during the evolution of cultivated sunflower. Genetics 171: 1933-1940.

Lai, Z., T. Nakazato, M. Salmaso, J.M. Burke, S. Tang, S.J. Knapp, and L.H. Rieseberg. 2005. Extensive chromosomal repatterning and the evolution of sterility barriers in hybrid sunflower species. Genetics 171: 291-303.

Wills, D.M., M.L. Hester, A. Liu and J.M. Burke. 2005. Chloroplast SSR polymorphisms in the Compositae and the mode of organellar inheritance in Helianthus annuus. Theor. Appl. Genet. 110: 941-947.

Wood, T.E., J.M. Burke and L.H. Rieseberg. 2005. Parallel genotypic adaptation: when evolution repeats itself. Genetica 123: 157-170.

Cornman, R.S., J.M. Burke, R.A. Wesselingh and M.L. Arnold. 2004. Contrasting genetic structure of adults and progeny in a Louisiana iris hybrid population. Evolution 58: 2669-2681.

Burke, J.M. 2004. When good plants go bad... Evolution 58:1637-1638.

Burke, J.M., Z. Lai, M. Salmaso, T. Nakazato, S. Tang, A. Heesacker, S.J. Knapp and L.H. Rieseberg. 2004. Comparative mapping and rapid karyotypic evolution in the genus Helianthus. Genetics 167: 449-457.