PMID- 12777523
OWN - NLM
STAT- MEDLINE
DCOM- 20040305
LR  - 20220408
IS  - 0737-4038 (Print)
IS  - 0737-4038 (Linking)
VI  - 20
IP  - 7
DP  - 2003 Jul
TI  - Adaptive evolution in the photosensory domain of phytochrome A in early 
      angiosperms.
PG  - 1087-97
AB  - Flowering plant diversity now far exceeds the combined diversity of all other 
      plant groups. Recently identified extant remnants of the earliest-diverging lines 
      suggest that the first angiosperms may have lived in shady, disturbed, and moist 
      understory habitats, and that the aquatic habit also arose early. This would have 
      required the capacity to begin life in dimly lit environments. If so, evolution 
      in light-sensing mechanisms may have been crucial to their success. The 
      photoreceptor phytochrome A is unique among angiosperm phytochromes in its 
      capacity to serve a transient role under conditions where an extremely high 
      sensitivity is required. We present evidence of altered functional constraints 
      between phytochrome A (PHYA) and its paralog, PHYC. Tests for selection suggest 
      that an elevation in nonsynonymous rates resulted from an episode of selection 
      along the branch leading to all angiosperm PHYA sequences. Most nucleotide sites 
      (95%) are selectively constrained, and the ratio of nonsynonymous to synonymous 
      substitutions on branches within the PHYA clade does not differ from the ratio on 
      the branches in the PHYC clade. Thus, positive selection at a handful of sites, 
      rather than relaxation of selective constraints, apparently has played a major 
      role in the evolution of the photosensory domain of phytochrome A. The episode of 
      selection occurred very early in the history of flowering plants, suggesting that 
      innovation in phyA may have given the first angiosperms some adaptive advantage.
FAU - Mathews, Sarah
AU  - Mathews S
AD  - Division of Biological Sciences, University of Missouri, USA. 
      mathewss@missouri.edu
FAU - Burleigh, J Gordon
AU  - Burleigh JG
FAU - Donoghue, Michael J
AU  - Donoghue MJ
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20030530
PL  - United States
TA  - Mol Biol Evol
JT  - Molecular biology and evolution
JID - 8501455
RN  - 0 (Phytochrome A)
RN  - 11121-56-5 (Phytochrome)
SB  - IM
MH  - *Evolution, Molecular
MH  - Flowering Tops/*growth & development
MH  - *Light
MH  - Magnoliopsida/*genetics
MH  - Morphogenesis
MH  - Phylogeny
MH  - Phytochrome/*genetics
MH  - Phytochrome A
MH  - Protein Structure, Tertiary
MH  - Selection, Genetic
EDAT- 2003/06/05 05:00
MHDA- 2004/03/06 05:00
CRDT- 2003/06/05 05:00
PHST- 2003/06/05 05:00 [pubmed]
PHST- 2004/03/06 05:00 [medline]
PHST- 2003/06/05 05:00 [entrez]
AID - msg123 [pii]
AID - 10.1093/molbev/msg123 [doi]
PST - ppublish
SO  - Mol Biol Evol. 2003 Jul;20(7):1087-97. doi: 10.1093/molbev/msg123. Epub 2003 May 
      30.