[Modification of the effect of UV irradiation on pine pollen by isolated cell constituents. Relation to radiation stimulation (author's transl.)].

The effect of UV-irradiation on the growth of pine pollen tubes can be modified by isolated fractions of cell extracts, especially by a fraction containing the cell wall material. Cell extracts irradiated with high UV-doses also stimulate the tube growth of unirradiated pollen grains. RNA, flavonoles and high-energy compounds (ATP, GTP and UTP) did not show any effect concerning tube growth stimulation. Some amino acids modified the tube growth of unirradiated pollen grains, while hydroxyproline, threonine, alanine, glutamic acid, proline and valine stimulated the tube growth. Cysteine, histidine, lysine, tryptophan and glutamine inhibit it. UV irradiation of the basic amino acids (i.e. lysine, arginine and histidine) increased, whereas irradiation of cysteine, glycine, tyrosine and isoleucine additionally decreased the tube growth.