Nuclear extrachromosomal DNA of higher plants

Recent reports indicate that minichromosomes and other small genetic entities may occur in the nuclei of uninfected higher plants. They become especially abundant under some special growth conditions and, sometimes, resemble extrachromosomal genes of ciliated protozoa. An example of such gene-sized DNA species was isolated from resting wheat embryos. The presence of telomeric sequences at its termini and the ability to replicate autonomously in wheat nuclei made it possible to distinguish this nuclear minichromosome from chromosomal DNA fragmentation products. The biological significance of plant minichromosomes remains to be elucidated.