Aluminium uptake sites in the primary root of Zea mays L.

Abstract

Histochemical studies of the chronological sequence involved in the uptake of Al by the primary root of Zea mays L., cv. TX 24, showed the primary sites of Al uptake to be the peripheral cells of the root cap and the mucilagenous secretions surrounding the root. Al spread rapidly through the cells of the root cap but the cap initials were the last cells to be reached. Entry of Al Into the rest of the root was considerably less rapid, and was found to be limited to the outer cortical cells of the root apex. Little evidence could be found of Al reaching actively dividing cell populations of the primary root meristem during the first 20 h of this experiment. The concept of Al acting directly on cell division is consequently questioned. Decapped root experiments implied a protective function for the root cap over the quiescent centre and mitotically active cells of the root. Epidermal cells of the root apex were not an effective barrier to Al. It is postulated that Al uptake is a function of the biochemical p...