Abstract Detail

Molecular Ecology and Evolution

Qiu, Yichun [1], Liu, Shao-Lun [2], Adams, Keith [1].

Concerted divergence of duplicated gene products in the Brassicaceae PRC2 complexes.

Gene duplication is a major contributor to genome evolution in eukaryotes. The divergence of individual duplicated genes is well documented; however, the co-divergence of duplicated genes whose products function together in a complex has not been described. We studied PRC2 (Polycomb Repressive Complex 2) in the Brassicaceae. The VRN2-complex comprises VRN2 and SWN, and both genes are duplicated to generate FIS2 and MEA, which form the Brassicaceae-specific FIS2-complex. The VRN2-complex regulates vegetative tissue differentiation and vernalization to control flowering time, but the FIS2-complex functions in gametophyte and seed development, preventing female gamete proliferation before fertilization, and facilitating endosperm cellularization after fertilization. We detected accelerated amino acid substitution rates in Brassicaceae FIS2 and MEA including in multiple functional domains, with evidence supporting positive selection. We analyzed microarray data from 63 organ types and developmental stages in Arabidopsis, and found that FIS2 and MEA have correlated expression patterns, which are restricted to flowers and seeds, but highly dissimilar to the broadly expressed VRN2 and SWN. We assayed expression of orthologs from outgroup species and found FIS2 and MEA have evolved to became reproductive organ-specific. Investigation of the epigenetic features in the Arabidopsis vegetative tissue identified that repressive histone marks are enriched in the FIS2 and MEA region, while active marks are associated with all their paralogs, suggesting a change in epigenetic regulation and explaining the loss of vegetative expression for FIS2 and MEA. Findings from this study, along with the known functions, allow us to conclude that FIS2 and MEA have diverged in concert to give rise to the new PRC2 complex in the Brassicaceae.

1 - UBC, Botany, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
2 - Tunghai University, Life Science, NO. 181, Section 3, Taichung Port Rd, Taichung, 40704, Taiwan

Keywords:
gene duplication
Brassicaceae
Polycomb group protein
Molecular divergence.

Presentation Type: Oral Paper:Papers for Topics
Session: 61
Location: Salon 15/16/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 9:15 AM
Number: 61006
Abstract ID:525
Candidate for Awards:None