Koh, Jin , Tate, Jennifer A. , Soltis, Pamela S. , Soltis, Douglas E. .
Evolution and expression of homoeologous loci in Tragopogon mirus (Asteraceae), a recently and repeatedly formed allopolyploid.
POLYPLOIDY has long been recognized as a major force in the evolution of plants. Studies of genome evolution and gene expression have been at the forefront of recent polyploidy research, but most of this work has focused on model plants or crop plants. Although many polyploid species have formed repeatedly, patterns of genome evolution and gene expression are largely unknown for populations of independent origin. We examined multiple individuals from several populations of independent origin of Tragopogon mirus; this allotetraploid formed repeatedly within the last 80 years from the diploids T. dubius and T. porrifolius. We sequenced 2221 ESTs derived from both flowers and leaves of T. dubius. After passing a quality check, 2038 sequences were used to compile 1050 unigenes. Using cDNA-AFLP display, we found evidence for differential expression patterns between T. mirus and its parents; these changes include apparent examples of gene silencing, novel expression, and maternal/paternal effects. In initial analyses using 19 EcoRI/MseI primer sets on ten individuals of each species, 1486 cDNA fragments were screened, and 782 (53 %) fragments were polymorphic among T. mirus, T. dubius, and T. porrifolius. Missing cDNA-AFLP fragments of either one or both parents in the allotetraploid accounted for 228 (15.3 %) of the total fragments, while 38 novel fragments were observed in the polyploids (2.6 % of total). Based on a comparison of sequenced cDNA-AFLP fragments with our ESTs and those in public databases, we have putative identifications for some of the differentially expressed genes from Tragopogon mirus. These genes are involved in a variety of cellular processes, including electron transfer and signal transduction.
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1 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
2 - University of Florida, Department of Botany, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 11:00 AM