The fine structure of meiotic chromosome pairing in natural and artificial Lilium polyploids

Abstract

In the autotetraploid Lilmm longiflonim (4n = 48), there are 12 sets of 4 homologous chromo somes. Within each set of 4 homologues, switches of pairing partners and crossovers occur at meiotic prophase. At the fine-structural level, the behaviour of the chromosomes is reflected in the switches between the axial cores of the homologous chromosomes. The normal synapto nemal complexes of the autotetraploid are compared with the complexes of the allotriploid L. tigrtnuvi, which have synaptonemal complexes with abnormal lateral elements. The possibility that the deformed lateral elements are the products of heteromorphisms between’ homologues’ is explored in the discussion. The observations on the chromosome cores are interpreted as support for the notion that the cores may be associated with the recombinationally active hereditary material during meiotic prophase.