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.
De Souza, T. B., Chaluvadi, S. R., Johnen, L., Marques, A., González-Elizondo, M. S., Bennetzen, J. L., & Vanzela, A. L. L. (2018). Analysis of retrotransposon abundance, diversity and distribution in holocentric Eleocharis (Cyperaceae) genomes. Annals of Botany, 122(2), 279–290. https://doi.org/10.1093/aob/mcy066