Xiang, Qui-Yun (Jenny) , Thomas, David , Zhang, Wenheng , Feng, Chunmiao .
Genome duplication and origin of polyploid species in the herbaceous dogwoods Cornus subg.Artocrania.
Genome duplication is known to be an important evolutionary force in plant speciation. In the herbaceous dogwoods, genome doubling resulted in the formation of a 4n species, C. unalaschkensis in the Pacific Northwest. The species has long been considered to evolve from hybridization of the two other herbaceous species in the genus that are diploid, C. suecica and C. canadensis, based on the intermediacy in morphology. However, our recent analysis of DNA sequences from the anthocyanin regulatory gene antR suggested the possibility of an autoploidy origin of the species involving neither C. suecica nor C. canadensis. We analyzed several additional molecular markers to understand the history of the group and to evaluate the alternative hypotheses regarding the origin of the 4n species. Specifically, ISSR markers and sequences from the nuclear genes WAXY, LEAFY, PISTILLATA, and APETALA3 as well as the chloroplast trnL-F region were analyzed. Flow cytometry was used to determine the ploidy level of sampled plants to ensure accuracy of inference of molecular data. ISSRs and all sequence data support a closer relationship of the 4n species to C. canadensis in the nuclear genome. The 4n species mostly shares alleles only with C. canadensis, and appears to lack C. suecica alleles, but in rare cases, it possesses the cpDNA of C. suecica. The gene genealogies also suggest a possible derived position of C. canadensis within C. unalaschkensis. The history of the 4n species appears to be complex involving multiple genome duplication events and is different from the traditional understanding. Various scenarios will be discussed.
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1 - North Carolina State University, Department of Plant Biology, 2115 Gardner Hall, Campus Box 7612, Raleigh, NC, 27695, USA
2 - North Carolina State University, Department of Botany, Campus Box 7612, Raleigh, North Carolina, 27695-7612, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Huron/Hilton
Date: Monday, July 9th, 2007
Time: 1:30 PM