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I am a postdoc in Sue Wessler's lab at the University of Georgia, Athens.  I am broadly interested in understanding genome evolution in flowering plants.  I use molecular and computational approaches to do comparative genomics.

Many organisms share genetic material across species boundaries, sometimes with profound phenotypic effects, such as widespread antibiotic resistance among bacteria.  This genetic sharing, known as horizontal gene transfer, has only recently been shown to occur in multicellular eukaryotes, and appears to be most prevalent among flowering plant mitochondrial genomes.  

Functional Horizontal Gene Transfer in Ginger Mitochondria 

Members of the Zingiberaceae contain a foreign mitochondrial nad1 from a eudicot donor.  While the genes involved in all but one of the known flowering plant transfers in the literature appear to be unused by the recipient, a portion of the foreign nad1 sequence in gingers appears to be functional.  The transfer and its aftermath left signs of recombination between the native and foreign copies of the gene, a process that may have enabled the foreign segment to supplant the native copy.

Massive Horizontal Gene Transfer in the Amborella Mitochondrial Genome

The mitochondrial genome of Amborella trichopoda contains in excess of one hundred foreign mitochondrial genes from multiple donors from multiple plant lineages: eudicots, mosses, and green algae.  The lack of foreign genes from chloroplast genomes or from non-plant donors suggests a plant mitochondrial specific transfer mechanism such as mitochondrial fusion. The Amborella mitochondrial genome contains an order of magnitude more native chloroplast-derived DNA than other sequenced mitochondrial genomes, and is also nearly an order of magnitude larger, suggesting that Amborella mitochondria may be more competent to DNA uptake than other plant mitochondria and might therefore incorporate more exogenous DNA as well as intracellular DNA.

Transposable Element Evolution In Flowering Plants 

Successful horizontal transfer requires that DNA physically travels from one organism to another and then is incorporated into the recipient genome.  Transposable elements (TEs) are good candidates for horizontal transfer because they have active mechanisms to insert themselves into new sites in a genome.  I am currently searching for evidence of the exchange of TEs among different species of grasses by identifying and collecting TE sequences from publicly available databases and using molecular evolutionary techniques to establish those with a history of horizontal transfer.  This project aims to identify both the grasses that share DNA and the families of TEs that are subject to transfer, and in so doing, clarify the mechanisms behind, and the consequences of, the horizontal transfer of DNA in plants.