Molecular evolution of psbA gene in ferns: Unraveling selective pressure and co-evolutionary pattern
Citation:
Sen, L., Fares, M., Su, Y.-J., Wang, T., Molecular evolution of psbA gene in ferns: Unraveling selective pressure and co-evolutionary pattern, BMC Evolutionary Biology, 12, 1, 2012, art. no. 145Download Item:
1471-2148-12-145.pdf (Published (publisher's copy) - Peer Reviewed) 536.7Kb
Abstract:
Abstract
Background:
The photosynthetic oxygen-evolving photo system II (PS II) produces almost the entire oxygen in the
atmosphere. This unique biochemical system comprises a functional core complex that is encoded by
psbA
and
other genes. Unraveling the evolutionary dynamics of this gene is of particular interest owing to its direct role in
oxygen production.
psbA
underwent gene duplication in leptosporangiates, in which both copies have been
preserved since. Because gene duplication is often followed by the non-fictionalization of one of the copies and its
subsequent erosion, preservation of both
psbA
copies pinpoint functional or regulatory specialization events. The
aim of this study was to investigate the molecular evolution of
psbA
among fern lineages.
Results:
We sequenced
psbA
, which encodes D1 protein in the core complex of PSII, in 20 species representing 8
orders of extant ferns; then we searched for selection and convolution signatures in
psbA
across the 11 fern orders.
Collectively, our results indicate that: (1) selective constraints among D1 protein relaxed after the duplication in 4
leptosporangiate orders; (2) a handful positively selected codons were detected within species of single copy
psbA
,
but none in duplicated ones; (3) a few sites among D1 protein were involved in co-evolution process which may
intimate significant functional/structural communications between them.
Conclusions:
The strong competition between ferns and angiosperms for light may have been the main cause for
a continuous fixation of adaptive amino acid changes in
psbA
, in particular after its duplication. Alternatively, a
single
psbA
copy may have undergone bursts of adaptive changes at the molecular level to overcome angiosperms
competition. The strong signature of positive Darwinian selection in a major part of D1 protein is testament to this.
At the same time, species own two
psbA
copies hardly have positive selection signals among the D1 protein
coding sequences. In this study, eleven co-evolving sites have been detected via different molecules, which may be
more important than others
Author's Homepage:
http://people.tcd.ie/faresmDescription:
PUBLISHED
Author: FARES, MARIO ALI
Type of material:
Journal ArticleCollections:
Series/Report no:
BMC Evolutionary Biology;12;
1;
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