Ascorbic acid effect on the onset of cell proliferation in pea root

The ability of ascorbic acid to induce cell proliferation of non-cycling cells was investigated in quiescent embryo root of Pisum sativum L. cv. Lincoln, as well as in the active plantlet root meristem, where a minor portion of the cells is non-proliferating. Quiescent embryo cells speeded up the G₀–G₁ transition during germination in the presence of ascorbic acid. In addition, proliferating cells present in the root tip of 3-day-old plantlets, arrested at the G₁/S boundary by hydroxyurea, resumed the cycle earlier than the control, when treated with ascorbic acid. In contrast, ascorbic acid was unable to induce the proliferation of non-cycling cells present in the active meristem. Therefore, these data suggest that the ability of ascorbic acid lo induce cell proliferation depends on the physiological status of the cell. In particular the data indicate that ascorbic acid is involved in cell proliferation as a factor necessary to enable already competent cells to progress through the cell cycle phases, but not as a factor able to induce non-competent cells to overcome proliferation arrest.