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.

Green smears

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.

Further reading

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