The CAS protein and Ca²⁺ signaling in the chloroplast of <em>Arabidopsis thaliana</em>

Abstract

There has been evidence that CAS forms a complex in the chloroplast of Chlamydomonas with PSI, CYTb6/f, and other proteins like PGRL1 and ANR1. However, in A. thaliana, such a CAS complex has not been shown yet. Therefore, one of the purposes of this study was to investigate whether CAS can also build a protein complex in the chloroplast of A. thaliana. On the other hand, to better understand the role of CAS in A. thaliana, growth phenotype and photosynthetic activity were investigated in a cas-knockout (casko) A. thaliana mutant line compared to wild-type plants (WT).<br /> CAS was also investigated as part of the Ca2+ signaling pathway in response to salt, mannitol, and oxidative stress. Using WT and casko mutant plants expressing the Ca2+ reporter AEQ, targeted to the cytosol, stroma, and thylakoid lumen, changes in [Ca2+] in response to these stimuli was examined. Additionally, this study has focused on identifying the potential sources of Ca2+ that may contribute to the change in [Ca2+].<br /> Furthermore, we also sought to determine the correct cellular localization of CML36, one of the 50 CMLs found in the A. thaliana, by using the full-length YFP-tag and the self-assembly GFP (saGFP) system in leaf tissue and isolated protoplasts and using laser confocal fluorescence microscopy.