期刊
PLANT PHYSIOLOGY
卷 171, 期 4, 页码 2317-2330出版社
AMER SOC PLANT BIOLOGISTS
DOI: 10.1104/pp.16.00652
关键词
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资金
- Ministero dell'Istruzione, dell'Universita e della Ricerca Fondo per gli Investimenti della Ricerca di Base (FIRB) [2010 RBFR10S1LJ_001]
- Regione Lombardia Filagro, Progetto di Ricerca di Ateneo [CPDA122838]
- binational DAAD/VIGONI grant
- Deutsche Forschungsgemeinschaft (DFG) [FOR964]
- DFG [SCHW1719/ 1-1, GRK2064, SCHW1719/5-1]
In eukaryotes, subcellular compartments such as mitochondria, the endoplasmic reticulum, lysosomes, and vacuoles have the capacity for Ca2+ transport across their membranes to modulate the activity of compartmentalized enzymes or to convey specific cellular signaling events. In plants, it has been suggested that chloroplasts also display Ca2+ regulation. So far, monitoring of stromal Ca2+ dynamics in vivo has exclusively relied on using the luminescent Ca2+ probe aequorin. However, this technique is limited in resolution and can only provide a readout averaged over chloroplast populations from different cells and tissues. Here, we present a toolkit of Arabidopsis (Arabidopsis thaliana) Ca2+ sensor lines expressing plastid-targeted FRET-based Yellow Cameleon (YC) sensors. We demonstrate that the probes reliably report in vivo Ca2+ dynamics in the stroma of root plastids in response to extracellular ATP and of leaf mesophyll and guard cell chloroplasts during light-to-low-intensity blue light illumination transition. Applying YC sensing of stromal Ca2+ dynamics to single chloroplasts, we confirm findings of gradual, sustained stromal Ca2+ increases at the tissue level after light-to-low-intensity blue light illumination transitions, but monitor transient Ca2+ spiking as a distinct and previously unknown component of stromal Ca2+ signatures. Spiking was dependent on the availability of cytosolic Ca2+ but not synchronized between the chloroplasts of a cell. In contrast, the gradual sustained Ca2+ increase occurred independent of cytosolic Ca2+, suggesting intraorganellar Ca2+ release. We demonstrate the capacity of the YC sensor toolkit to identify novel, fundamental facets of chloroplast Ca2+ dynamics and to refine the understanding of plastidial Ca2+ regulation.
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