It is shown that callose synthesis in the <em>Oenothera biennis </em>pollen tube is regulated by the endogenous Ca<sup>2+</sup> level. Calcium antagonists reduced the amount of callose in the wall above the tip of the pollen tube (Verapamil - calcium channels blocker) and at the tube tip after stopping tube growth (La<sup>3+</sup> - a Ca<sup>2+</sup> substitute). Ruthenium red and ionophore A 23187, which raise the Ca 21 level in the cytoplasm, induced callose synthesis at the tip of pollen tube.
The effect of intracellular calcium level regulators on the synthesis of pollen tube callose in Oenothera biennis L.