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Autor/a:
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García-Plazaola, José Ignacio; Fernández-Marín, beatriz; Ferrio Díaz, Juan Pedro; Alday, Josu G.; Hoch, Günter; Landais, Damien; Milcu, Alexandru; Tissue, David T.; Voltas Velasco, Jordi; Gessler, Arthur; Roy, Jacques; Resco de Dios, Víctor
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Notes:
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There is increasing evidence that the circadian clock is a signif-
icant driver of photosynthesis that becomes apparent when
environmental cues are experimentally held constant. We
studied whether the composition of photosynthetic pigments
is under circadian regulation, and whether pigment oscillations
lead to rhythmic changes in photochemical efficiency. To
address these questions, we maintained canopies of bean and
cotton, after an entrainment phase, under constant (light or
darkness) conditions for 30–48 h. Photosynthesis and quantum
yield peaked at subjective noon, and non-photochemical
quenching peaked at night. These oscillations were not associ-
ated with parallel changes in carbohydrate content or xantho-
phyll cycle activity. W e observed robust oscillations of Chl a/b
during constant light in both species, and also under constant
darkness in bean, peaking when it would have been night dur-
ing the entrainment (subjective nights). These oscillations
could be attributed to the synthesis and/or degradation of tri-
meric light-harvesting complex II (reflected by the rhythmic
changes in Chl a/b), with the antenna size minimal at night
and maximal around subjective noon. Considering together
the oscillations of pigments and photochemistry, the observed
pattern of changes is counterintuitive if we assume that the
plant strategy is to avoid photodamage, but consistent with a
strategy where non-stressed plants maximize photosynthesis.
The authors acknowledge the support of the following re-
search grants: UPV/EHU-GV IT-624-13 and IT-1018-16
from the Basque Government and CTM2014-53902-C2-2-P
from the Spanish Ministry of Economy and Competitiveness
(MINECO) and the ERDF (FEDER). This study benefited
from the CNRS human and technical resources allocated to
the Ecotrons Research Infrastructures as well as from the
state allocation ‘Investissement d’Avenir’ ANR-11-INBS-
0001, ExpeER FP7 Transnational Access programme,
Ramón y Cajal fellowships (RYC-2012-10970 to V.R.D.
and RYC-2008-02050 to J.P.F.), the Erasmus Mundus Master
Course Mediterranean Forestry and Natural Resources
Management (MEDfOR) and internal grants from UWS-
HIE to V.R.D. and ZALF to A.G. EHU postdoctora
ellowship and JdC-Incorporation fellowship (IJCI-2014-
22489) to B.F.M. are also acknowledged. We remain indebted
to E. Gerardeau, D. Dessauw, J. Jean, P. Prudent (Aïda
CIRAD), J.-J. Drevon, C. Pernot (Eco&Sol INRA), B.
Buatois, A. Rocheteau (CEFE CNRS), S. Devidal, C. Piel,
O. Ravel and the full Ecotron team, J. del Castillo, P. Martín,
A. Mokhtar, A. Pra, S. Salekin (UdL), S. García-Muñoz
(IMIDRA), Z. Kayler and K. Pirhofer-Walzl (ZALF) for out-
standing technical assistance during experiment setup, plant
cultivation or subsequent measurements. |
