Chloroplast envelope K/H antiporters are involved in cytosol pH regulation.

Variations in light intensity induce cytosol pH changes in photosynthetic tissues, providing a possible signal to adjust a variety of biochemical, physiological and developmental processes to the energy status of the cells. It was shown that these pH changes are partially due to the transport of protons in or out of the thylakoid lumen. However, the ion transporters in the chloroplast that transmit these pH changes to the cytosol are not known.

Improved yield, fruit quality, and salt resistance in tomato co-overexpressing and genes.

The K, Na/H antiporter LeNHX2 and the regulatory kinase SlSOS2 are important determinants of salt tolerance in tomato plants and their fruit production ability. In this work, we have analyzed the effects of and co-overexpression on fruit production, quality in tomato plants ( L. cv.

Loss of function of the chloroplast membrane K/H antiporters AtKEA1 and AtKEA2 alters the ROS and NO metabolism but promotes drought stress resilience.

Potassium (K) exerts key physiological functions such as osmoregulation, stomatal movement, membrane transport, protein synthesis and photosynthesis among others. Previously, it was demonstrated in Arabidopsis thaliana that the loss of function of the chloroplast KEfflux Antiporters KEA1 and KEA2, located in the inner envelope membrane, provokes inefficient photosynthesis. Therefore, the main goal of this study was to evaluate the potential impact of the loss of function of those cation transport systems in the metabolism of reactive oxygen and nitrogen species (ROS and RNS).

Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark.

Photosynthesis and carbon fixation depend critically on the regulation of pH in chloroplast compartments in the daylight and at night. While it is established that an alkaline stroma is required for carbon fixation, it is not known how alkaline stromal pH is formed, maintained or regulated. We tested whether two envelope transporters, AtKEA1 and AtKEA2, directly affected stromal pH in isolated Arabidopsis chloroplasts using the fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF).