Genomic instability in a clonal species, Tradescantia commelinoides (Commelinaceae)

Abstract

Within a population of Tradescantia commelinoides collected in the wild, genomic instability is unique to clones having large centric shifts. Initially, the instability is attributable to breakage caused by imperfect separation of abnormally long chromatids, but the more severe effects that sometimes develop are a consequence of spontaneous breakage and reunion and disturbance of control mechanisms. Breakage of excessively long chromatids following repositioning of the centromere may destabilize some segment of DNA important for ordered replication and division. Eventual stability would result from the loss of this segment, or its transfer to a quiescent position. A period of instability, leading to the establishment of a new equilibrium, may represent an important source of variability in species that rely heavily upon vegetative reproduction for their colonizing potential.Key words: Tradescantia, clonal species, centric shift, genomic instability, karyotype orthoselection.