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Nat Plants ; 7(8): 998-1009, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34373605


For decades, the dynamic nature of chlorophyll a fluorescence (ChlaF) has provided insight into the biophysics and ecophysiology of the light reactions of photosynthesis from the subcellular to leaf scales. Recent advances in remote sensing methods enable detection of ChlaF induced by sunlight across a range of larger scales, from using instruments mounted on towers above plant canopies to Earth-orbiting satellites. This signal is referred to as solar-induced fluorescence (SIF) and its application promises to overcome spatial constraints on studies of photosynthesis, opening new research directions and opportunities in ecology, ecophysiology, biogeochemistry, agriculture and forestry. However, to unleash the full potential of SIF, intensive cross-disciplinary work is required to harmonize these new advances with the rich history of biophysical and ecophysiological studies of ChlaF, fostering the development of next-generation plant physiological and Earth-system models. Here, we introduce the scale-dependent link between SIF and photosynthesis, with an emphasis on seven remaining scientific challenges, and present a roadmap to facilitate future collaborative research towards new applications of SIF.

Clorofila A/fisiologia , Ciências da Terra , Fluorescência , Biologia Molecular , Fotossíntese/fisiologia , Folhas de Planta/fisiologia , Tecnologia de Sensoriamento Remoto/métodos
Proc Natl Acad Sci U S A ; 117(30): 17499-17509, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32690715


Coping of evergreen conifers in boreal forests with freezing temperatures on bright winter days puts the photosynthetic machinery in great risk of oxidative damage. To survive harsh winter conditions, conifers have evolved a unique but poorly characterized photoprotection mechanism, a sustained form of nonphotochemical quenching (sustained NPQ). Here we focused on functional properties and underlying molecular mechanisms related to the development of sustained NPQ in Norway spruce (Picea abies). Data were collected during 4 consecutive years (2016 to 2019) from trees growing in sun and shade habitats. When day temperatures dropped below -4 °C, the specific N-terminally triply phosphorylated LHCB1 isoform (3p-LHCII) and phosphorylated PSBS (p-PSBS) could be detected in the thylakoid membrane. Development of sustained NPQ coincided with the highest level of 3p-LHCII and p-PSBS, occurring after prolonged coincidence of bright winter days and temperatures close to -10 °C. Artificial induction of both the sustained NPQ and recovery from naturally induced sustained NPQ provided information on differential dynamics and light-dependence of 3p-LHCII and p-PSBS accumulation as prerequisites for sustained NPQ. Data obtained collectively suggest three components related to sustained NPQ in spruce: 1) Freezing temperatures induce 3p-LHCII accumulation independently of light, which is suggested to initiate destacking of appressed thylakoid membranes due to increased electrostatic repulsion of adjacent membranes; 2) p-PSBS accumulation is both light- and temperature-dependent and closely linked to the initiation of sustained NPQ, which 3) in concert with PSII photoinhibition, is suggested to trigger sustained NPQ in spruce.

Fotossíntese , Picea/fisiologia , Estações do Ano , Proteínas das Membranas dos Tilacoides/metabolismo , Tilacoides/metabolismo , Sequência de Aminoácidos , Meio Ambiente , Complexos de Proteínas Captadores de Luz/metabolismo , Noruega , Fosforilação , Espectrometria de Massas em Tandem , Proteínas das Membranas dos Tilacoides/química , Árvores
J Exp Bot ; 70(12): 3211-3225, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-30938447


Pinaceae are the predominant photosynthetic species in boreal forests, but so far no detailed description of the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Picea abies (L.) Karst). We first customized a spruce thylakoid protein database from translated transcript sequences combined with existing protein sequences derived from gene models, which enabled reliable tandem mass spectrometry identification of P. abies thylakoid proteins from two-dimensional large pore blue-native/SDS-PAGE. This allowed a direct comparison of the two-dimensional protein map of thylakoid protein complexes from P. abies with the model angiosperm Arabidopsis thaliana. Although the subunit composition of P. abies core PSI and PSII complexes is largely similar to that of Arabidopsis, there was a high abundance of a smaller PSI subcomplex, closely resembling the assembly intermediate PSI* complex. In addition, the evolutionary distribution of light-harvesting complex (LHC) family members of Pinaceae was compared in silico with other land plants, revealing that P. abies and other Pinaceae (also Gnetaceae and Welwitschiaceae) have lost LHCB4, but retained LHCB8 (formerly called LHCB4.3). The findings reported here show the composition of the photosynthetic apparatus of P. abies and other Pinaceae members to be unique among land plants.

Fotossíntese/genética , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Picea/genética , Sequência de Aminoácidos , Complexo de Proteínas do Centro de Reação Fotossintética/química , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Filogenia , Picea/metabolismo , Alinhamento de Sequência , Tilacoides/metabolismo
Physiol Plant ; 162(2): 156-161, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28815613


Photosystem I (PSI) has evolved in anaerobic atmospheric conditions and until today remains susceptible to oxygen. To minimize the probability of damaging side reactions, plants have evolved sophisticated mechanisms to control electron transfer, and PSI becomes inhibited only when malfunctions of these regulatory mechanisms occur. Because of the complicated induction of PSI photoinhibition, a detailed investigation into the process and following reactions are still largely missing. Here, we introduce the theoretical framework and a novel method for an easy and controlled induction of PSI photoinhibition in vivo. The method mimics the PSI damage mechanisms of fluctuating light-sensitive mutant plants (stn7, pgr5) which cannot control electron donation to PSI. Because PSII and PSI have different light absorption properties, electrons accumulate in the intersystem electron transfer chain (ETC), if PSII is preferentially excited. A saturating light pulse given upon an over-reduced ETC leads to the saturation of PSI electron acceptors, ultimately leading to the production of reactive oxygen species and photoinhibition of PSI. By adjusting the time of the light treatment, PSI can be gradually photoinhibited, providing a novel tool to holistically investigate the PSI photoinhibition phenomenon.

Oxigênio/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transporte de Elétrons/genética , Transporte de Elétrons/efeitos da radiação , Luz , Mutação , Oxirredução/efeitos da radiação , Fotossíntese/genética , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema I/genética , Plantas/genética