Cytoplasmic inheritance in Nicotiana tabacum L. autoradiography

Tobacco pollen grains were labelled with leucine 14C, part then being used for artificial pollination of specific Nicotiana lines, while the rest were processed directly, as controls, for light and electron microscopy and autoradiography. The apparent differences in silver grain density observed in the controls may be related to the different physiological states of pollen grains during labelling. A radioactive precursor does not impair the viability and fertility of pollen grains. Samples taken and observed at successive intervals after pollination allowed the monitoring of cytoplasmic transmission to the embryo sac. The cytoplasmic materials remain confined within the micropylar canal and the embryo sac for several days after pollination. The tagged mitochondria found in the embryo sac are not necessarily of male origin, since the radioactive materials they contain might be products of metabolism. (author)