The role of Golgi-localized transport proteins in cellular calcium homeostasis and salt tolerance of Arabidopsis thaliana

During evolution, plants have developed the ability to respond to a wide range of abiotic and biotic stresses. Despite their astonishing ability to cope with strenuous conditions, soil salinization is increasingly threatening agricultural production and crop yield. Salt tolerance mechanisms have thus been a topic of high interest in research and agriculture. Recent work of the laboratory has identified Ca2+ transport into the Golgi apparatus as a potentially important determinant of salt tolerance. This thesis aims to investigate the role of two Golgi-localized transport proteins, ECA3 and BICAT3, in responses of the model plant Arabidopsis thaliana to salt stress. ECA3 and BICAT3 are a Golgi-localized Ca2+ and Mn2+ pump and transporter, respectively, and eca3 mutants as well as bicat3 eca3 double mutants had been identified to be hypersensitive to salt stress. In this work, bicat3 and eca3 single and double mutants were further evaluated for their phenotype under salt stress conditions. Since both proteins function as Ca2+ transporters, both local and systemic Ca2+ signals in response to salt stress were analysed by compartment-specific fluorescent and luminescent Ca2+ indicators to eventually identify impairment in Ca2+ signalling upon salt perception, focusing on the level of the cytosol and the Golgi apparatus.