Involvement of the Phosphoinositide Signaling Pathway in the Anti‐Senescence Effect of Low‐Concentration Stressors on Detached Barley Leaves

The effect of low concentration of some stress-inducing compounds of different toxicity and chemical nature like Pb and Ti salts or DCMU on the senescence of chloroplasts was investigated in detached primary leaves of barley (Hordeum vulgare cv. Omega). These agents stimulated chlorophyll accumulation, photosynthetic activity ((14)CO (2) fixation), and decreased the number of plastoglobuli in chloroplasts compared to the control, thus delaying senescence. Low-concentration stressors did not increase the level of active cytokinins of leaves during the treatment. Lithium and stearoylcarnitine chloride inhibited the stimulating effect of stressors. This points to the involvement of the PIP (2)-IP (3)/DAG signal transduction pathway in generation of the specific responses.