Meiotic Behavior of Accessory Chromosomes and their Distribution in Natural Population of Lilium medeoloides A. GRAY

Abstract

1) Three types of accessory chromosomes, E, e and ee were found in Lilium medeoloides A. Gray. Their maintenance in mitotic tissue was complete since little few intra-plant variation in their number and size was detected.
2) Meiotic disjunction of the accessory chromosomes was often irregular conditioned by a) their mode of conjugation, b) their position in spindle apparatus at MI, and c) their size, the small size being defective in anaphase disjunction.
3) Fifteen different karyotypes were distinguished with respect to the number and type of these accessory chromosomes among 117 individuals obtained from nine aggregates of this plant. Adding to these, one triploid plant, which did not include any accessory chromosomes, was found.
4) All the plants obtained from three aggregates had no accessory chromosomes and, therefore, their karyotype was fixed, being 2n. Only one type of accessory chromosome, E, was found in one of the aggregates examined. The remaining aggregates included different types of accessory chromosomes in various combinations both in number and kind.
5) Mapping of individuals bearing flower buds was made at two localities where an aggregate of this plant was chosen for investigation. Active sexual reproduction was confirmed in one of the two which was the most polymorphic in karyotypic constitution. In another, which included no accessory chromosomes and accordingly revealed no karyotypic variation decline of sexual propagation was inferred.