Endogenous circadian rhythms in pigment composition induce changes in photochemical efficiency in plant canopies

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2017-02-01Author
García-Plazaola, José Ignacio
Fernández-Marín, beatriz
Hoch, Günter
Landais, Damien
Milcu, Alexandru
Tissue, David T.
Gessler, Arthur
Roy, Jacques
Suggested citation
García-Plazaola, José Ignacio;
Fernández-Marín, beatriz;
Ferrio Díaz, Juan Pedro;
Alday, Josu G.;
Hoch, Günter;
Landais, Damien;
...
Resco de Dios, Víctor.
(2017)
.
Endogenous circadian rhythms in pigment composition induce changes in photochemical efficiency in plant canopies.
Plant Cell and Environment, 2017, vol. 40, p. 1153-1162.
https://doi.org/10.1111/pce.12909.
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Show full item recordAbstract
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.