Molecular Ecology and Evolution
Lindqvist, Charlotte , Albert, Victor A. .
Variation in ABNORMAL FLORAL ORGANS (AFO) corroborates a reticulate ancestry for the Hawaiian endemic mints (Lamiaceae).
The Hawaiian endemic mints (Lamiaceae), which represent one of the largest Hawaiian plant radiations, apparently diversified from a single introduction to the Hawaiian Islands. Previous results have suggested that the native Hawaiian mints likely originated from polyploid ancestors in North American (NA) Stachys, a large and nearly-cosmopolitan genus in subfamily Lamioideae. Based on 5S non-transcribed spacer (5S-NTS) sequences, the Hawaiian mints are most closely related to temperate NA Stachys, whereas with cpDNA sequence data, they group with a largely Mesoamerican Stachys lineage. This phylogenetic incongruence between nuclear and organellar DNA data indicates a reticulate ancestry for the Hawaiian mints. In order to investigate this possibility further, we are analyzing sequence variation in a putative homolog of the axial regulator AFO (ABNORMAL FLORAL ORGANS; otherwise known as FILAMENTOUS FLOWER or YABBY1), a member of a small transcription factor family. Preliminary results show extensive length and nucleotide variation at the 3'-end of the gene both within and among individuals of NA Stachys and Hawaiian mints. Analyses of the divergent alleles/paralogs group them into at least two major lineages, one (A) representing temperate NA Stachys and the Hawaiian mints, and the other (B) consisting of all included individuals except for species with principally Eastern NA distributions. Meso- and South American Stachys taxa are only found in lineage B. These results corroborate earlier suggestions that North America was invaded twice by different Stachys lineages. We hypothesize that the two lineages reticulated in a geographical area roughly corresponding to southwestern USA; hence, Stachys individuals from this area derive from two different ancestral polyploid genomes, and share alleles from both AFO sequence lineages. We suggest that individuals from this region later colonized the Hawaiian Islands.
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Lindqvist C, et al. 2006. An expressed sequence tag (EST) library from developing fruits of an Hawaiian endemic mint (Stenogyne rugosa, Lamiaceae): characterization and microsatellite markers. BMC Plant Biology, 6:16.
-- Plant Genome Network (Stenogyne ESTs and unigenes)
1 - University of Oslo, Natural History Museum, P.O. Box 1172 Blindern, Oslo, NO-0318, Norway
ABNORMAL FLORAL ORGANS
Presentation Type: Oral Paper:Papers for Topics
Location: Boulevard B/Hilton
Date: Wednesday, July 11th, 2007
Time: 9:30 AM