Retrotransposons in holocentric chromosomes of Eleocharis with different ploidy levels

Long terminal repeat-retrotransposons (LTR-RTs) comprise a large portion of plant genomes, with massive repeat blocks distributed across the chromosomes. Eleocharis (Cyperaceae) species have holocentric chromosomes, and show a positive correlation between chromosome numbers and the amount of nuclear DNA.

de Souza et al. present an overview of the diversity and the role of several Copia and Gypsy LTR-RT families in the organization of Eleocharis holocentric chromosomes. Physical location using Copia and Gypsy probes on the chromosomes indicated different distribution patterns of this genomic fractions representing >50% of genomes.

Rapid and unequal changes in the LTR-RTs represent important mechanisms responsible for genomic differentiation, karyotype evolution and speciation, but LTR-RT number variations seem to be a secondary mechanism in comparison to polyploidy when considering DNA C-values.