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Abstract Detail

Genetics Section

Sinn, Brandon T. [1], Sedmak, Dylan [2], Kelly, Lawrence [3], Freudenstein, John [4].

Structural and Syntenic Variability in Asaraceae Plastomes: A phylogenetic perspective.

Previously, we presented sequenced, but non-circularized, plastomes of two Asarum species, A. canadense (Asarum sect. Asarum) and A. minus (Asarum sect. Hexastylis); these genomes represent the first rearranged plastomes reported from the magnoliids. Complete circularization of these genomes has been nontrivial due to lengthy AT-rich regions, rearrangements, and transfers to the nuclear and mitochondrial genomes. To provide a phylogenetic perspective to our findings, and to determine if the disruptions found in these two species are a general characteristic of Asarum plastomes, we have expanded our sampling and have now sequenced the plastome of Saruma henryi as well as four other Asarum species to include one species from each subgeneric section (A. epigynum, Asarum sect. Geotaenium; A. sieboldii, Asarum sect. Asiasarum; A. megacalyx, Asarum sect. Heterotropa; A. delavayi, Asarum sect. Longistylis). We find that the plastome of Saruma is highly similar to that of Piper cenocladum, the only other published plastome from the Piperales, although its IRs have undergone boundary shifts. The recovery of a typical magnoliid plastome in Saruma suggests that our findings in Asarum are restricted to that group, and are not a previously overlooked general characteristic of the magnoliids. Furthermore, it is apparent that the rearrangement of the LSC is more dramatic than previously reported; the LSC region from trnY-GUA to trnH-GUG (~30,000 bp) has been inverted in Asarum. trnH-GUG has not been found thus far in the plastome of Asarum, but is found with several mutations, relative to Piper, in Saruma; this suggests that trnH-GUG was lost prior to the LSC inversion. The SSC and LSC boundaries of the IR have shifted throughout the history of Asarum, and our denser sampling has revealed that the addition of rps19 through rpl14 to the IR is the pleisiomorphic condition in the genus. We also find that the duplication of the SSC initiated early in the history of Asarum. The ndhA exon 1 and the accompanying intron of A. epigynum, which has been recovered as sister to the remainder of Asarum in previous studies, has been duplicated in the IR, and preliminary evidence suggests that the entirety of the SSC has been duplicated in sections Asiasarum, Heterotropa, and Longistylis; this implies a loss of this duplication in section Hexastylis. The ladder-like topology of Asarum, along with incremental changes to plastomes throughout the genus, suggests that denser sampling can better inform us of the precursors of angiosperm plastome change.

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1 - Ohio State University, Evolution, Ecology and Organismal Biology, 1315 Kinnear Road, Columbus, OH, 43212, USA
2 - Ohio State University
3 - The New York Botanical Garden, Bronx, NY, 10458, USA
4 - Ohio State University, Museum Of Biological Diversity, 1315 Kinnear Rd, Columbus, OH, 43212-1157, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 6
Location: Salon 15/16/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 10:30 AM
Number: 6010
Abstract ID:776
Candidate for Awards:Margaret Menzel Award

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