Has glyceraldehyde-3-phosphate dehydrogenase a role in the early response of Hordeum maritimum L. to potassium deprivation?

摘要

This research was conducted to investigate in the halophyte Hordeum maritimum the production of lipid and antioxidative signals as early response to K+ deprivation. In contrast to leaves, roots showed a decrease in K+ content, which reached a minimum value after 6 h of treatment. At the end of the experiment, K+ content was 25% lower than the control. Phosphatidylation of butanol was used for an in vivo assay of phospholipase D (PLD) in plant tissues. In the roots, phosphatidylbutanol (PTBut) showed a biphasic trend with two peaks after 2 and 24 h of potassium deprivation while in the leaves no PTBut formation was observed. In the roots, hydrogen peroxide (H₂O₂) content increased during K+ deprivation with a maximum after 6 h, decreasing thereafter. The leaves showed a similar trend, although the changes in H₂O₂ were smaller. On the contrary, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity decreased, reaching the minimum value at 6 h, increasing thereafter. In the leaves after a decrease at 2 h of treatment, the activity of the enzyme increased slightly. Deprivation of K+ behaves as an oxidative stress bringing to the production of H₂O₂. The secondary activation of PLD at 24 h of treatment could be due to structural changes of GAPDH, following inactivation by H₂O₂, which allows PLD to be activated.