Chromosome elimination in Paspalum subciliatum (Notata group)

Abstract

 This paper reports the occurrence of chromosome elimination during microsporogenesis in a Brazilian accession of Paspalum subciliatum. The accession was tetraploid (2n=4x=40) and meiosis was normal until diakinesis, with 20 regularly distributed bivalents. Starting at metaphase I, meiosis was very peculiar. In this phase, while ten bivalents were clustered in the equatorial plate, the other ten were still dispersed in the cytoplasm. In anaphase I the chromosomes showed different abilities to migrate to the poles. While one genome reached the poles in telophase I, the laggard was in metaphase or anaphase and was engulfed by extra nuclei. In the second division, behavior was the same. Our results show clear asynchrony in cell cycle, especially in some meiotic phases. Unfortunately we cannot explain the causes of the phenomenon, but this event shows once more that chromosome elimination serves as an incompatibility barrier preventing divergent genomes from coexisting in the same cellular system. The chromosome elimination affected pollen fertility but did not impair seed viability.