Two spatially and temporally distinct Ca2+ signals convey Arabidopsis thaliana responses to K+ deficiency. Issue 2 (31st August 2016)

• Record Type: Journal Article
• Authors: Behera, Smrutisanjita; Long, Yu; Schmitz‐Thom, Ina; Wang, Xue‐Ping; Zhang, Chunxia; Li, Hong; Steinhorst, Leonie; Manishankar, Prabha; Ren, Xiao‐Ling; Offenborn, Jan Niklas; Wu, Wei‐Hua; Kudla, Jörg; Wang, Yi
• Is Part Of: New phytologist. Volume 213:Issue 2(2017)
• Page Start: 739
• Page End: 750
• Publication Date: 2016-08-31
• Subjects: Arabidopsis thaliana -- calcium -- cameleon YC3.6 -- high‐resolution calcium imaging -- K+ channel -- nutrient starvation -- potassium -- signaling; Botany -- Periodicals; 580
• DOI: 10.1111/nph.14145
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: In plants, potassium (K + ) homeostasis is tightly regulated and established against a concentration gradient to the environment. Despite the identification of Ca 2+ ‐regulated kinases as modulators of K + channels, the immediate signaling and adaptation mechanisms of plants to low‐K + conditions are only partially understood. To assess the occurrence and role of Ca 2+ signals in Arabidopsis thaliana roots, we employed ratiometric analyses of Ca 2+ dynamics in plants expressing the Ca 2+ reporter YC3.6 in combination with patch‐clamp analyses of root cells and two‐electrode voltage clamp (TEVC) analyses in Xenopus laevis oocytes. K + deficiency triggers two successive and distinct Ca 2+ signals in roots exhibiting spatial and temporal specificity. A transient primary Ca 2+ signature arose within 1 min in the postmeristematic stelar tissue of the elongation zone, while a secondary Ca 2+ response occurred after several hours as sustained Ca 2+ elevation in defined tissues of the elongation and root hair differentiation zones. Patch‐clamp and TEVC analyses revealed Ca 2+ dependence of the activation of the K + channel AKT1 by the CBL1–CIPK23 Ca 2+ sensor‐kinase complex. Together, these findings identify a critical role of cell group‐specific Ca 2+ signaling in low K + responses and indicate an essential and direct role of Ca 2+ signals for AKT1 K + channel activation in roots.