Abstract
Mitochondria play a central role in the energy metabolism of plants. At the same time, they provide energy for plant stress responses. We here report a first view on the mitochondrial Oxidative Phosphorylation (OXPHOS) system of the halophile (salt tolerant) plant Cakile maritima. Mitochondria were purified from suspension cultures of C. maritima and for comparison of Arabidopsis thaliana, a closely related glycophyte (salt sensitive) plant. Mitochondria were treated with digitonin and solubilized protein complexes were analyzed by 2D Blue native/SDS polyacrylamide gel electrophoresis. The OXPHOS systems of the two compared plants exhibit some distinct differences. C. maritima mitochondria include a very abundant respiratory supercomplex composed of monomeric complex I and dimeric complex III. At the same time the complexes II and IV are of reduced abundance. The stability of the OXPHOS complexes was investigated by combined salt and temperature treatments of isolated mitochondria. ATP synthase (complex V) is of increased stability in C. maritima. Also, the I + III2 supercomplex is present in high abundance during stress treatments. These results give insights into the mitochondrial contribution to the plant salt stress response.
Highlights
Halophile plants have extraordinary competence to live on soils with high contents of salt
Establishment of A. thaliana and C. maritima Cell Suspension Culture Arabidopsis thaliana and C. maritima cell suspension cultures were established as outlined in May and Leaver (1993): Calli were transferred into 500 mL Erlenmeyer flasks containing 100 mL medium composed of 0.3% (w/v) Gamborg B5 medium supplemented with 3% (w/v) sucrose, 0.01% (w/v) 2,4-D and 0.001% (w/v) kinetin
This study is dedicated to the Oxidative Phosphorylation (OXPHOS) system of C. maritima
Summary
Halophile plants have extraordinary competence to live on soils with high contents of salt. This aptitude is based on various physiological properties, like active salt secretion from cells, innercellular accumulation of salt in the vacuole and the biosynthesis of compatible osmolytes like proline or glycine betaine (Munns and Gilliham, 2015). Increased inner-cellular salt concentrations can cause severe damages, e.g., denaturation of proteins and formation of reactive oxygen species (ROS). Halophile plants have particular capabilities to cope with these circumstances. They may have enhanced intra-cellular levels of reductants, such as ascorbate, glutathione or NADPH, which counteract increased ROS formation (Ismail and Horie, 2017). At the same time, enhanced levels of heat stress proteins can stabilize the native structures of proteins
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