THE CYTOLOGY OF PLANTLETS DERIVED FROM CULTURED ANTHERS OF NICOTIANA SYLVESTRIS

SUMMARY Cultured anthers of Nicotiana sylvestris produced 70% haploid, 14% diploid, 8% triploid, 2% tetraploid and 6% mixaploid plantlets. Immediately pre‐mitotic anthers produced no plantlets; mitotic and immediately post‐mitotic ones did so. Stage of anther development at initiation of culture was not related to production of non‐haploids. Embryoids arose from divisions of the vegetative nucleus. In microspores containing globular embryoids 0, 1 or 2 nuclei derived from the generative nucleus could be recognised; these, however, contributed few if any viable cells to the developing plantlets. Metaphase plates with higher than the haploid number of chromosomes were seen and probably arose through nuclear fusion at an early stage.