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

摘要: 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 chloroplast K+Efflux Antiporters KEA1 KEA2, located inner envelope membrane, provokes inefficient photosynthesis. Therefore, main goal this study to evaluate potential impact those cation transport systems metabolism reactive oxygen nitrogen species (ROS RNS). Using 14-day-old seedlings from double knock-out kea1kea2 mutants, ROS NO content roots green cotyledons were studied at biochemical level. The AtKEA1 AtKEA2 did not cause oxidative stress but provoked an alteration homeostasis affecting some ROS-generating enzymes. These included glycolate oxidase (GOX) NADPH-dependent superoxide generation activity, enzymatic non-enzymatic antioxidants both NADP-isocitrate dehydrogenase NADP-malic enzyme activities. content, analyzed by confocal laser scanning microscopy (CLSM), negatively affected photosynthetic non-photosynthetic organs mutant seedlings. Furthermore, S-nitrosoglutathione reductase (GSNOR) expression activity downregulated whereas tyrosine nitrated profile, immunoblot, unaffected relative each immunoreactive band changed. Moreover, mutants showed increased photorespiratory pathway stomata closure, thus promoting a higher resilience drought stress. Data suggest osmotic balance integrity maintained are necessary keep ROS/RNS metabolism. these data open new questions about how endogenous might be K+/H+ chloroplasts.