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Features of CAM-cycling expressed in the dry season by terrestrial and epiphytic plants of Clusia arrudae Planchon & Triana in two rupestrian savannas of southeastern Brazil in comparison to the C 3 -species Eremanthus glomerulatus Less.

Scarano, Fabio ; Mattos, Eduardo ; Franco, Augusto ; Cavalin, Pedro ; Orthen, Birgit ; Fernandes, G. ; Lüttge, Ulrich

Trees, 2016, Vol.30(3), pp.913-922 [Periódico revisado por pares]

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  • Título:
    Features of CAM-cycling expressed in the dry season by terrestrial and epiphytic plants of Clusia arrudae Planchon & Triana in two rupestrian savannas of southeastern Brazil in comparison to the C 3 -species Eremanthus glomerulatus Less.
  • Autor: Scarano, Fabio ; Mattos, Eduardo ; Franco, Augusto ; Cavalin, Pedro ; Orthen, Birgit ; Fernandes, G. ; Lüttge, Ulrich
  • Assuntos: CAM-cycling ; Clusia arrudae ; Leaf angles ; Midday depression ; Photosynthesis ; Rupestrian savannas
  • É parte de: Trees, 2016, Vol.30(3), pp.913-922
  • Descrição: To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1007/s00468-015-1331-z Byline: Fabio R. Scarano (1,2), Eduardo A. Mattos (2), Augusto C. Franco (3), Pedro O. Cavalin (2), Birgit Orthen (4), G. Wilson Fernandes (5), Ulrich Luttge (6) Keywords: CAM-cycling; Clusia arrudae; Leaf angles; Midday depression; Photosynthesis; Rupestrian savannas Abstract: Key message In rupestrian savannas in southeastern Brazil Clusia arrudae Planchon & Triana in the dry season performed CAM-cycling with very little gas exchange in the early morning followed by a long depression during the rest of the day. CAM-cycling is considered as a survival strategy under drought and the productivity of the plant which is quite abundant must rely on performance of C .sub.3 -photosynthesis in more favorable seasons. Abstract In rupestrian savannas in the Serra do Cipo (19[degrees]14 48.9a[sup.3]S, 43[degrees]30 36.0a[sup.3]W) at 1300 m a.s.l. and in the Serra de Sao Jose (21[degrees]08 S, 44[degrees]17 W) at 1010--1030 m a.s.l. in southeastern Brazil Clusia arrudae Planchon & Triana is abundant. As CAM is frequent in the genus Clusia we supposed that it would perform CAM as a drought adaptation at the very dry rupestrian savanna sites in the dry season. At the Serra do Cipo site as control we studied the obligate C.sub.3-species Eremanthus glomerulatus Less. Both species are sympatric at this site. Eremanthus glomerulatus performed C.sub.3-photosynthesis with a midday depression. The patterns of C. arrudae were completely different so that genuine C.sub.3-photosynthesis was excluded, but they were also not typical of CAM. The stomata were almost closed during the night. Some stomatal opening and net CO.sub.2 uptake occurred in the early morning hours followed by a long depression with stomatal closure throughout the rest of the day. Nevertheless, photo inhibition was limited and photosynthetic electron transport rate remained high during this time indicating that photosynthetic excitation energy was required and suggesting that CO.sub.2 assimilation was continuing behind closed stomata based on internal sources of CO.sub.2. There was some nocturnal accumulation of organic acids (malic and citric acids) which could represent a source of CO.sub.2 during the light period. Overall, the observations can be best explained by the performance of CAM-cycling by C. arrudae. However, leaf carbon gain of C. arrudae was much inferior to that of E. glomerulatus. CAM-cycling appears to be a strategy for protection from photoinhibitory damage and survival under strong conditions of drought. Steeper more vertical leaf positions observed would assist reducing overheating during stomatal closure at high irradiance. The abundance of C. arrudae suggests that the plant must have other means to sustain productivity such as full C.sub.3-photosynthesis in the more favorable seasons. Author Affiliation: (1) Fundacao Brasileira para o Desenvolvimento Sustentavel, Rua Engenheiro Alvaro Niemeyer, 76, Sao Conrado, Rio de Janeiro, RJ, CEP 22610-180, Brazil (2) Departamento de Ecologia, Universidade Federal do Rio de Janeiro (UFRJ), CCS, IB, Caixa Postal 68020, Rio de Janeiro, RJ, CEP 21941-970, Brazil (3) Departamento de Botanica, Universidade de Brasilia, Caixa Postal 04457, Brasilia, DF, CEP 70919-970, Brazil (4) Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany (5) Lab. Ecologia Evolutiva e Biodiversidade/ICB, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 486, 30161-970, Brazil (6) Department of Biology, Darmstadt University of Technology, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany Article History: Registration Date: 19/11/2015 Received Date: 08/07/2015 Accepted Date: 19/11/2015 Online Date: 19/12/2015 Article note: Communicated by J. Penuelas.
  • Idioma: Inglês

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