The burning glass effect of water droplets triggers a high light-induced calcium response in the chloroplast stroma
Year: 2025
Type: article
Abstract: Plants rely on water and light for photosynthesis, but water droplets on leaves can focus light into high-intensity spots, risking photodamage. Excessive light can impair growth or induce cell death, making it essential for plants to detect and respond to light fluctuations. While Ca 2+ signaling has been linked to high light (HL) acclimation, the subcellular dynamics remain unclear. Here, we investigate Ca 2+ responses to HL exposure in Arabidopsis thaliana . Using a glass bead to simulate light-focusing by water droplets, a biphasic increase of Ca 2+ concentration was detected in the chloroplast stroma by the genetically encoded calcium indicator YC3.6 and confirmed using a newly established stroma-localized R-GECO1 (NTRC-R-GECO1). The stromal response was largely independent of light wavelength and unaffected in phot1 phot2 and cry1 cry2 mutants. Chemical inhibition of photosynthetic electron transport, microscopy-based Fv/Fm experiments, and measurement of the reactive oxygen species (ROS)-redox balance with roGFP-based reporters and Singlet Oxygen Sensor Green (SOSG) chemical dye suggested that photodamage and singlet oxygen contribute to the stromal Ca 2+ response. While blue and white light also triggered a Ca 2+ response in the cytosol and nucleus, pharmacological inhibition with cyclopiazonic acid (CPA) and loss-of-function mutants of the Ca 2+ transporters BIVALENT CATION TRANSPORTER 2 (BICAT2) and endoplasmic reticulum (ER)-type Ca 2+ -ATPase (ECA) suggested that the HL response depends on a Ca 2+ exchange between the ER and chloroplast stroma. The response was primarily light dependent but accelerated by increasing external temperature. This study implicates a novel Ca 2+ -mediated acclimation mechanism to HL stress, a process of growing relevance in the context of climate change.
Source: Current Biology
Authors: Dominic Kuang, Shanna Romand, Anna S. Zvereva, Bianca Maria Orlando Marchesano, Matteo Grenzi, Stefano Buratti, Qun Yang, Ke Zheng, Dimitra Valadorou, Evelien Mylle, Zuzana Benedikty, Martin Trtílek, Maria Tenje, Cornelia Spetea, Daniël Van Damme, Bernhard Wurzinger, Markus Schwarzländer, Markus Teige, Alex Costa, Simon Stael
Institutions: Swedish University of Agricultural Sciences, University of Vienna, University of Milan, University of Münster, Uppsala University, Science for Life Laboratory, Ghent University, VIB-UGent Center for Plant Systems Biology, Photon Systems Instruments (Czechia), University of Gothenburg, National Research Council
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $7,030
Funders: Università degli Studi di Milano, European Commission, Deutsche Forschungsgemeinschaft, Universität Heidelberg, Austrian Science Fund, Ministero dell’Istruzione, dell’Università e della Ricerca, Knut och Alice Wallenbergs Stiftelse, China Scholarship Council, Horizon 2020 Framework Programme, European Research Council, H2020 Fast Track to Innovation, HORIZON EUROPE European Research Council
Awards: G1000454745, G1603186574, Calcium Regulation of Chloroplast Development & Function, G1985338727, G2011963735, G2027470444, Towards increased biosafety for non-target insects - Damage-activated proteolysis to selectively enhance toxicity of pesticides, G3684850888, G4259872236, G4622516607, G4834780958, G4937468798, G6172483028, G6760318878, G7506158010, G8084962297, G8311313351, G889665740, G92535956, G987703576
OpenAlex ID: W4410511785