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Abstract Detail


Genetics Section

Janssens, Steven [1], Geuten, Koen [1], Huysmans, Suzy [1], Smets, Erik [2].

Evolution of the AP3/DEF K-domain and C-terminal domain in Impatiens.

CLASS B genes, comprising APETALA3/DEFICIENS (AP3/DEF) and PISTILLATA/GLOBOSA (PI/GLO) lineages are required for petal and stamen identity. Recent studies identified two AP3/DEF-like genes in the genus Impatiens with strongly divergent C-terminal domains (ImpDEF1 and ImpDEF2). One of these C-terminal domains is truncated with loss of the euAP3 and PI motif (ImpDEF2), while the other turned out to be unusually long but with euAP3 and PI motif (ImpDEF1) present. In this study the molecular evolution of the AP3/DEF-like genes in Impatiens (Balsaminaceae, Ericales) was investigated. We sequenced Intron 4, 5, and 6 of the K-domain together with the C-terminal domain of the two AP3/DEF duplicates. K-domain introns and exons of both paralogues were examined for alternative splicing, positive selection, intron length variation, and differences in relative rate. Also, the molecular evolution of the C-terminal domain in ImpDEF1 and ImpDEF2 was investigated. ImpDEF1 and ImpDEF2 were compared in order to find out what evolutionary events might have caused the strong divergence of the C-terminus of both AP3/DEF paralogues. Our results recognized Intron 4, 5, and 6 in AP3/DEF-like genes as a valuable source of characters for phylogenetic studies at the infrageneric level. In some Impatiens species alternative splice sites were located independently in both ImpDEF1 and ImpDEF2. Additionally, Intron 5 in ImpDEF2 shows a strong length extension in more recently diversified lineages. By comparing the evolution of the C-terminal domain of both paralogues, we observed that the C-terminal domain of ImpDEF1 is strongly divergent. In contrast, the C-terminal domain of the truncated ImpDEF2 is conserved evolutionarily. We suggest that both paralogues are still functional and are probably subfunctionalized after duplication.[c.e.:srb]


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1 - Institute of Botany and Microbiology, Department of Biology, Laboratory of Plant Systematics, Kasteelpark Arenberg 31, Leuven, B-3001, Belgium
2 - National Herbarium of the Netherlands, Leiden University branch, P.O.Box 9514, Leiden, NL-2300 RA, Netherlands

Keywords:
Impatiens
C-terminal domain
K-domain
Balsaminaceae
Ericales
molecular evolution
class B MADS-box genes.

Presentation Type: Poster:Posters for Sections
Session: 48-74
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM
Abstract ID:466


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