{"entity": "publication", "iuid": "6c22279ffebd49ab99ea3d166521f1d3", "timestamp": "2026-08-20T20:28:20.166Z", "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/publication/6c22279ffebd49ab99ea3d166521f1d3.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/publication/6c22279ffebd49ab99ea3d166521f1d3"}}, "title": "The burning glass effect of water droplets triggers a high light-induced calcium response in the chloroplast stroma.", "authors": [{"family": "Kuang", "given": "Dominic", "initials": "D"}, {"family": "Romand", "given": "Shanna", "initials": "S"}, {"family": "Zvereva", "given": "Anna S", "initials": "AS"}, {"family": "Orlando Marchesano", "given": "Bianca Maria", "initials": "BM"}, {"family": "Grenzi", "given": "Matteo", "initials": "M"}, {"family": "Buratti", "given": "Stefano", "initials": "S"}, {"family": "Yang", "given": "Qun", "initials": "Q"}, {"family": "Zheng", "given": "Ke", "initials": "K"}, {"family": "Valadorou", "given": "Dimitra", "initials": "D"}, {"family": "Mylle", "given": "Evelien", "initials": "E"}, {"family": "Benedikty", "given": "Zuzana", "initials": "Z"}, {"family": "Trt\u00edlek", "given": "Martin", "initials": "M"}, {"family": "Tenje", "given": "Maria", "initials": "M"}, {"family": "Spetea", "given": "Cornelia", "initials": "C"}, {"family": "Van Damme", "given": "Dani\u00ebl", "initials": "D"}, {"family": "Wurzinger", "given": "Bernhard", "initials": "B"}, {"family": "Schwarzl\u00e4nder", "given": "Markus", "initials": "M"}, {"family": "Teige", "given": "Markus", "initials": "M"}, {"family": "Costa", "given": "Alex", "initials": "A"}, {"family": "Stael", "given": "Simon", "initials": "S"}], "type": "journal article", "published": "2025-06-09", "journal": {"title": "Curr. Biol.", "issn": "1879-0445", "volume": "35", "issue": "11", "pages": "2642-2658.e7", "issn-l": "0960-9822"}, "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 Ca2+ signaling has been linked to high light (HL) acclimation, the subcellular dynamics remain unclear. Here, we investigate Ca2+ responses to HL exposure in Arabidopsis thaliana. Using a glass bead to simulate light-focusing by water droplets, a biphasic increase of Ca2+ 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 Ca2+ response. While blue and white light also triggered a Ca2+ response in the cytosol and nucleus, pharmacological inhibition with cyclopiazonic acid (CPA) and loss-of-function mutants of the Ca2+ transporters BIVALENT CATION TRANSPORTER 2 (BICAT2) and endoplasmic reticulum (ER)-type Ca2+-ATPase (ECA) suggested that the HL response depends on a Ca2+ exchange between the ER and chloroplast stroma. The response was primarily light dependent but accelerated by increasing external temperature. This study implicates a novel Ca2+-mediated acclimation mechanism to HL stress, a process of growing relevance in the context of climate change.", "doi": "10.1016/j.cub.2025.04.065", "pmid": "40398414", "labels": [], "xrefs": [{"db": "pii", "key": "S0960-9822(25)00562-7"}], "notes": [], "created": "2026-08-20T07:53:33.694Z", "modified": "2026-08-20T07:53:33.746Z"}