A plastid protein crucial for Ca(2+)-regulated stomatal responses

作者：Weinl Stefan^*; Held Katrin; Schluecking Kathrin; Steinhorst Leonie; Kuhlgert Sebastian; Hippler Michael; Kudla Joerg

来源：NEW PHYTOLOGIST, 2008, 179(3): 675-686.

DOI：10.1111/j.1469-8137.2008.02492.x

• calcium
• chloroplast
• Ca(2+)-sensing receptor (CAS)
• guard cells
• signal transduction
• stomatal movement

Guard cell movements are regulated by environmental cues including, for example, elevations in extracellular Ca(2+) concentration. Here, the subcellular localization and physiological function of the Ca(2+)-sensing receptor (CAS) protein was investigated.
CAS protein localization was ascertained by microscopic analyses of green fluorescent protein (GFP) fusion proteins and biochemical fractionation assays. Comparative guard cell movement investigations were performed in wild-type and cas loss-of-function mutant lines of Arabidopsis thaliana. Cytoplasmic Ca(2+) dynamics were addressed in plants expressing the yellow cameleon reporter protein YC3.6.
This study identified CAS as a chloroplast-localized protein that is crucial for proper stomatal regulation in response to elevations of external Ca(2+). CAS fulfils this role through modulation of the cytoplasmic Ca(2+) concentration.
This work reveals a novel role of the chloroplast in cellular Ca(2+) signal transduction.

• 出版日期2008