Biology subjects

Terese, M.

Publications and source records attributed to Terese, M..

2 recordsLinked to original sources

bioRxiv2025

Guanosine tetraphosphate (ppGpp) signalling promotes high-light tolerance in Arabidopsis thaliana.

Guanosine tetraphosphate (ppGpp) is a hyperphosphorylated nucleotide originally discovered in prokaryotes and found in the chloroplasts of plants and algae. In plants, ppGpp signalling plays a role as a regulator of photosynthetic activity, which is important in acclimation to environmental stresses such as nitrogen limitation. However, the full range of stresses involving ppGpp signalling is not yet known. Here, we investigated the role of ppGpp accumulation in the acclimation of plants to high light. We found that the over-accumulation of ppGpp in transgenic lines that overexpress RSH3 (OX:RSH3) increases tolerance to high light intensity. Although ppGpp leads to higher non-photochemical energy dissipation (NPQ) than in wild-type plants, we show that NPQ is not critical for the enhanced high-light tolerance. Rather, our results show that ppGpp accumulation leads to broad changes in plant physiology that prime plants to resist and subsequently recover from high light exposure. ppGpp levels themselves also increase in response to high light exposure, suggesting that ppGpp signalling may play a physiological role in high light acclimation. Our work highlights the importance of ppGpp signalling in plant stress acclimation.

plant biology↗

bioRxiv2019

Topoisomerase VI participates in an insulator-like function that prevents H3K9me2 spreading into euchromatic islands

The organization of the genome into transcriptionally active and inactive chromatin domains requires well-delineated chromatin boundaries and insulator functions in order to maintain the identity of adjacent genomic loci with antagonistic chromatin marks and functionality. In plants that lack known chromatin insulators, the mechanisms that prevent heterochromatin spreading into euchromatin remain to be identified. Here, we show that DNA Topoisomerase VI participates in a chromatin boundary function that safeguards the expression of genes in euchromatin islands within silenced heterochromatin regions. While some transposable elements are reactivated in mutants of the Topoisomerase VI complex, genes insulated in euchromatin islands within heterochromatic regions of the Arabidopsis thaliana genome are specifically downregulated. H3K9me2 levels consistently increase at euchromatin island loci and decrease at some TE loci. We further show that Topoisomerase VI physically interacts with S-adenosylmethionine (SAM) synthase MAT3, which is required for H3K9me2 deposition. Topoisomerase VI promotes MAT3 occupancy on heterochromatic elements and its exclusion from euchromatic islands, thereby providing a mechanistic insight into the essential role of Topoisomerase VI in the delimitation of chromatin domains.

plant biology↗