SIMS imaging of Ca and Na, and effect of the ionic interaction Ca Na on wall maturation of phloem fibres and xylem cells of hypocotyls of beech seedlings

Using SIMS microscopy an unexpected ionic interaction between calcium and s odium has been characterised within the walls of the xylem cells and of the phloem fibres of hypocotyls of beech seedlings: whereas a decrease of the Na signal in the cell walls was always paralleled by an increase of the cal cium signal at the same site, unexpectedly an increase of the normalised Na signal in the cell walls of the Na-enriched seedlings was paralleled by an increase of the Ca signal. We have also shown that this interaction was in volved in the differentiation of the secondary walls. ((C) Academie des sci ences / Elsevier, Paris.)