Abstract Detail

Molecular Ecology and Evolution

Ikeda, Hajime [1], Gustafsson, Lovisa  [2], Brochmann, Christian  [3], Nagatani, Akira  [4], Setoguchi, Hiroaki [5].

Molecular evolution of photoreceptor genes between sister species and non-neutral divergence along latitude.

Given well-known ecotypic divergences in phenology among plants inhabiting different latitude, natural selection from environments that change along latitude such as photoperiods is one of forces driving adaptive divergence in plants. Since photoreceptors play essential roles in regulating plants’ lifecycles via light signals, functional changes in photoreceptors could supply a series of adaptive modification of plant lifecycles. Thereby, photoreceptors themselves are plausibly targets of natural selection along latitude. To evaluate this hypothesis, we elucidated evolutionary history of photoreceptor genes between recently diverged sister species distributing in higher (Cardamine bellidifolia; Brassicaceae, distributed in N45-75 ) and lower latitude (Cardamine nipponica, distributed in N35-43 ). Among six photoreceptors (PHYA, PHYB, PHYC, PHYE, CRY1, CRY2), PHYB evolved under non-neutral manner due to accumulation of amino acid replacements between the species (MK test; P<0.05), especially on the branch of lower latitude species (C. nipponica) due to relaxation of selective constraints (branch-site test, P < 0.05). Furthermore, three amino acid replacements that fixed between the species were found in the PHY domain, a domain involving in stability of active conformation of phytochrome (Pfr) in darkness. These finding implies that functions of PHYB of these two species may be diverged in relevance to adaptation to the length of night, i.e., photoperiod. Although we are testing this implication by a biochemical assay as well as physiological experiments, present results suggest that functional changes in a photoreceptor would be involved in the adaptive divergence between sister species in lower and higher latitude.

1 - Okayama University, Institute Of Plant Science And Resources, 2-20-1 Chuo, Kurashiki, N/A, 710-0046, Japan
2 - University of Oslo, Natural History Museum , Blindern, Oslo, NO-0318 , Norway
3 - University of Oslo, Natural History Museum, Blindern, Oslo, Norway
4 - Kyoto University, Graduate School of Science, Kitashirakawa-Oiwake-Cho, Kyoto, 606-8502, Japan
5 - Kyoto University, Graduate School of Human and Environmental Studies, Yoshida-Nihonmatsu-cho, Kyoto, 606-8501, Japan

Keywords:
alpine
phytochrome
photoreceptor
allopatric speciation
local adaptation.

Presentation Type: Oral Paper:Papers for Topics
Session: 28
Location: Firs South/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 1:30 PM
Number: 28001
Abstract ID:540
Candidate for Awards:Margaret Menzel Award