Distinct Responses of Arabidopsis Telomeres and Transposable Elements to Zebularine Exposure

Abstract

Involvement of epigenetic mechanisms in the regulation of telomeres and transposable elements (TEs), genomic regions with the protective and potentially detrimental function, respectively, has been frequently studied. Here, we analyzed telomere lengths in Arabidopsis thaliana plants of Columbia, Landsberg erecta and Wassilevskija ecotypes exposed repeatedly to the hypomethylation drug zebularine during germination. Shorter telomeres were detected in plants growing from seedlings germinated in the presence of zebularine with a progression in telomeric phenotype across generations, relatively high inter-individual variability, and diverse responses among ecotypes. Interestingly, the extent of telomere shortening in zebularine Columbia and Wassilevskija plants corresponded to the transcriptional activation of TEs, suggesting a correlated response of these genomic elements to the zebularine treatment. Changes in lengths of telomeres and levels of TE transcripts in leaves were not always correlated with a hypomethylation of cytosines located in these regions, indicating a cytosine methylation-independent level of their regulation. These observations, including differences among ecotypes together with distinct dynamics of the reversal of the disruption of telomere homeostasis and TEs transcriptional activation, reflect a complex involvement of epigenetic processes in the regulation of crucial genomic regions. Our results further demonstrate the ability of plant cells to cope with these changes without a critical loss of the genome stability.

Genomic impact of stress-induced transposable element mobility in Arabidopsis

“…Importantly, it has been documented that treatments with DNA methylation inhibiting drugs such as zebularine can lead to DNA damage ( 41 ). Indeed, chromosome breakages have been documented in several plant species ( 41 , 42 ) and changes in telomere length have also been observed ( 43 ). We therefore first wanted to assess the magnitude of DNA damage caused by the drug treatments used to mobilize ONSEN .…”

Traces of Genetic but Not Epigenetic Adaptation in the Invasive Goldenrod Solidago canadensis Despite the Absence of Population Structure

“…When there were changes in frequency, they were bidirectional: Up to 44.1% of epigenetic loci, i.e., MSAP-m and MSAP-n loci combined, showed a fourfold decrease, but up to 21.3% showed a fourfold increase in frequency. This nondirectional change might be attributed to an increase in the level of transposable elements due to zebularine treatment, as found for Arabidopsis thaliana ecotypes (Konečná et al, 2021). With our approach, we could link the variation in two of these anonymous loci to climatic and spatial genetic variation, but more specific associations will need further analyses of the underlying mechanistic context, e.g., using next-generation approaches (Schield et al, 2016;Werner et al, 2020).…”

Epigenetics for Crop Improvement in Times of Global Change

“…DNA methylation has been suggested to play a role in suppressing transposon activity. Therefore, increased activity of transposons is anticipated upon 5-AzaC or Zebularine treatment, which was confirmed by Nishimura [ 134 ], Konečná [ 135 ], and Boonjing [ 136 ]. Another group of applications focuses on the fact that the activity of the transgene in genetically transformed tissues is silenced by DNA methylation of the promoter contained in the transgenic construct.…”