Highly repeated DNA and holocentric chromosomes of the woodrush Luzula flaccida (Juncaceae)

Abstract

Three highly repeated DNA components were characterized from Luzula flaccida. The 1.683 g/cm3 satellite accounts for 22% of the genome and has a sequence complexity of 127 base pairs (BP). A further 8% of the genome consists of a cryptic satellite DNA with a repeating unit of 190 BP. A minor satellite component of buoyant density 1.681 g/cm3 constitutes less than 2% of the total DNA and has a unit length of 184 BP. The presence of segments of the 1.683 satellite DNA lacking Mbol cleavage sites suggests that amplification of sequence variants may have occurred during the evolution of this satellite. While the distribution of satellite DNA appears to be different in being interspersed along the holocentric chromosomes of L. flaccida, the structure and mode of evolution of highly repeated DNA appears to follow the same pattern as seen in organisms with localized centromeres.Key words: Luzula, holocentry, highly repeated DNA.