Zinc in pollen and its incorporation into seeds.

A study on the distribution of radioactive zinc ((65)Zn) in flowers of Vicia faba L. and Nicotiana tabacum L. showed the highest activity, expressed as cpm/mg dry weight, in pollen Also, using a histochemical method, it was observed that a portion of the naturally occurring zinc present in pollen grains was transferred into their growing tubes during germination. Calculations in based on the specific activity in (65)Zn-labelled pollen grains and in seeds from flowers pollinated with this pollen showed that about 68% of the radioisotope content of the pollen was incorporated into the seeds. The significance of these results and the possible role of zinc in fertilization is discussed.