Abstract Detail

Systematics Section/ASPT

Knox, Eric [1].

Foreign DNA Trafficking at the Inversion Hot-Spot in Plastid Genomes of the Lobeliaceae (Campanulales).

Relative to the tobacco-like ancestral organization of plastid genomes, five large inversions were previously hypothesized to account for the plastome arrangement in Lobelia fervens (based on Southern blot analysis).  There are 60 possible five-step scenarios that could account for the rearrangements, but only one scenario had common cause due to a postulated 'hot-spot' that served as one endpoint for all five inversions.  Recent plastome sequencing provides evidence based on the phylogenetic distribution of inversions in the Lobeliaceae and the reconstruction of inferred ancestral sequences that the order of inversions was correctly inferred and a hot-spot exists.  The phylogenetic sampling identified related species that have only one, two, or four of the five inversions found in L. fervens (and L. erinus), which provides evidence that Inversions 1, 2, and 5 occurred during different phylogenetic intervals.  No species is currently known to have only three of these inversions, but one endpoint of Inversion 4 is slightly offset from the hot-spot, and a small segment of intergenic DNA normally located upstream of trnC (GCA) now sits upstream of trnR (UCU), which indicates that Inversion 3 must have preceded Inversion 4.  The hot-spot is a recombinogenic region located upstream of psaI (the deletion site formerly occupied by accD) that is characterized by dynamic stem-loop structures, the insertion of duplicated DNA segments from elsewhere in the plastome (duplicative transposition), and the insertion of foreign DNA segments that carry large open-reading frames.  In some cases, this foreign DNA trafficking occurred without disrupting the plastome organization, but in other cases, inversions were evidently cause by this DNA trafficking.

1 - Indiana University, Department of Biology, 1001 East Third Street, Bloomington, IN, 47405, USA

Keywords:
Lobelia
plastid genome
inversion
foreign DNA.

Presentation Type: Oral Paper:Papers for Sections
Session: 45
Location: River Fork/Grove
Date: Wednesday, July 30th, 2014
Time: 4:30 PM
Number: 45012
Abstract ID:603
Candidate for Awards:None