TY - JOUR
T1 - The occurrence of crassulacean acid metabolism in Cymbidium (Orchidaceae) and its ecological and evolutionary implications
AU - Motomura, H.
AU - Yukawa, T.
AU - Ueno, O.
AU - Kagawa, A.
N1 - Funding Information:
Acknowledgments We thank Mr Kazuhiro Suzuki for skillful cultivation of the plant materials and Dr Shuichi Noshiro for logistical assistance throughout the experiments. This study is partly supported by Grants-in-Aid to Scientific Research from the Japan Society for Promotion of Science (Nos. 13640708 and17370033).
PY - 2008/3
Y1 - 2008/3
N2 - Crassulacean acid metabolism (CAM) is one of the photosynthetic pathways regarded as adaptations to water stress in land plants. Little is known about correlations among the level of CAM activity, environment of habitat, life form, and phylogenetic relationship of a plant group from an evolutionary perspective. We examined these relationships in 18 species of Cymbidium (Orchidaceae) because the genus shows distinctive diversification of habitats and life forms. The photosynthetic type was classed into three categories, strong CAM, weak CAM, and C3 on the basis of CAM activity. CAM expression in Cymbidium was confined to the epiphytic and lithophytic species. Especially, all of these species from tropical to subtropical rainforest exhibited CAM activity. On the other hand, the terrestrial species always exhibited C3 metabolism irrespective of their varied habitats. Regarding the evolution of photosynthetic characters, weak CAM was the ancestral state in Cymbidium and strong CAM and C3 metabolism occurred subsequently. The evolution of strong CAM likely enabled Cymbidium to extend to exposed sites in tropical lowland where marked water stress exists. Further, different levels of CAM activity characterized each species and such potential plasticity of CAM may realize the radiation of Cymbidium into sites with different environmental conditions.
AB - Crassulacean acid metabolism (CAM) is one of the photosynthetic pathways regarded as adaptations to water stress in land plants. Little is known about correlations among the level of CAM activity, environment of habitat, life form, and phylogenetic relationship of a plant group from an evolutionary perspective. We examined these relationships in 18 species of Cymbidium (Orchidaceae) because the genus shows distinctive diversification of habitats and life forms. The photosynthetic type was classed into three categories, strong CAM, weak CAM, and C3 on the basis of CAM activity. CAM expression in Cymbidium was confined to the epiphytic and lithophytic species. Especially, all of these species from tropical to subtropical rainforest exhibited CAM activity. On the other hand, the terrestrial species always exhibited C3 metabolism irrespective of their varied habitats. Regarding the evolution of photosynthetic characters, weak CAM was the ancestral state in Cymbidium and strong CAM and C3 metabolism occurred subsequently. The evolution of strong CAM likely enabled Cymbidium to extend to exposed sites in tropical lowland where marked water stress exists. Further, different levels of CAM activity characterized each species and such potential plasticity of CAM may realize the radiation of Cymbidium into sites with different environmental conditions.
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U2 - 10.1007/s10265-007-0144-6
DO - 10.1007/s10265-007-0144-6
M3 - Article
C2 - 18246297
AN - SCOPUS:40549096357
SN - 0918-9440
VL - 121
SP - 163
EP - 177
JO - Journal of Plant Research
JF - Journal of Plant Research
IS - 2
ER -
