DDM1 and ROS1 have a role in UV-B induced- and oxidative DNA damage in A. thaliana

Absorption of UV-B by DNA induces the formation of covalent bonds between adjacent pyrimidines. In maize and arabidopsis, plants deficient in chromatin remodeling show increased DNA damage compared to WT plants after a UV-B treatment. However, the role of enzymes that participate in DNA methylation in DNA repair after UV-B damage was not previously investigated. In this work, we analyzed how chromatin remodeling activities that have an effect on DNA methylation affects the repair of UV-B damaged DNA using plants deficient in the expression of DDM1 and ROS1. First, we analyzed their regulation by UV-B radiation in arabidopsis plants. Then, we demonstrated that ddm1 mutants accumulated more DNA damage after UV-B exposure compared to Col0 plants. Surprisingly, ros1 mutants show less CPDs and 6-4PPs than WT plants after the treatment under light conditions, while the repair under dark conditions is impaired. Transcripts for two photolyases are highly induced by UV-B in ros1 mutants, suggesting that the lower accumulation of photoproducts by UV-B is due to increased photorepair in these mutants. Finally, we demonstrate that oxidative DNA damage does not occur after UV-B exposure in arabidopsis plants; however, ros1 plants accumulate high levels of oxoproducts, while ddm1 mutants have less oxoproducts than Col0 plants, suggesting that both ROS1 and DDM1 have a role in the repair of oxidative DNA damage. Together, our data provide evidence that both DDM1 and ROS1, directly or indirectly, participate in UV-B induced- and oxidative DNA damage repair.Fil: Qüesta, Julia I.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; ArgentinaFil: Fina, Julieta Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; ArgentinaFil: Casati, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad Nacional de Rosario; Argentin

Non-coding cis polymorphisms destabilize epigenetic memory in plants

Trabajo presentado al Virtual Meeting Epiplant, celebrado del 8 al 12 de febrero de 2021.Peer reviewe

Epigenome dynamics underlying the seed-to-seedling transition in Arabidopsis

Trabajo presentado en International Conference on Arabidopsis Research (ICAR2022), evento celebrado en Belfast (Irlanda del Norte) entre el 20 y el 24 de junio de 2022

Epigenetic mechanisms controlling plant developmental transitions

Trabajo presentado en IBMCP Seminars 2022, celebrado en Valencia el 25 de marzo de 2022.As sessile organisms, plants need to align their development to specific external cues from the different seasons. To be capable of inferring seasonal information, plants have evolved systems to sense environmental signals, and also to ‘remember’ previous exposure to these signals. Epigenetic regulation is subject to environmental influence and can store information over time. In this context, Polycomb Repressive Complexes (PRC1 and PRC2) define chromatin repressive states, ensuring the correct execution of the plant developmental program. In Arabidopsis thaliana, phase transitions such as germination and flowering rely on PRC2-dependent epigenetic silencing of key developmental genes. The site-specific recruitment of PRC2 to its targets depends on the VAL subfamily of B3 transcription factors. Our lab aims at further revealing the mechanistic aspects of VAL regulation in triggering epigenetic silencing of key developmental genes

Epigenetic mechanisms enabling plant growth under stressful environments

Trabajo presentado en EMBO Workshop "Molecular responses of plants facing climate change" celebrado en Montpellier (Francia) entre el 13 y el 17 de junio de 2022

Mechanisms of epigenetic regulation of transcription by lncRNAs in plants

Altres ajuts: Junior Leader Fellowship [LCF/BQ/PI19/11690003] from "laCaixa" Foundation [ID100010434]Long noncoding RNAs (lncRNAs) are an ubiquitous feature of eukaryotic genomes and in recent decades have been shown to be highly abundant and varied. Many prominent examples have been described as having essential roles in regulating the expression of genes in different developmental and environmental contexts. As a result, much work has been done on elucidating the mechanisms by which they modulate the expression of protein coding genes. In this review, we focus on those which have been characterized in plants. We specifically examine common epigenetic mechanisms that regulate gene expression at the level of transcription. In this regard, we focus on the lncRNAs in plants that have primarily been associated with controlling the chromatin environment of genes at the level of modifications, RNA POLYMERASE II (RNAPII) processivity and efficiency of transcription, and mediating the formation of transcriptionally activating and repressive chromatin loops. We discuss open questions in plant lncRNA epigenetic regulation and opportunities for future study of functionally significant lncRNAs with yet-unknown epigenetic mechanisms

UV-B radiation induces Mu element somatic transposition in maize

The maize Mutator (MuDR/Mu) transposon family is the most active DNA transposon inplants (Lisch 2002). The Mu family contains diverse elements, all sharing similar ~215 bpterminal inverted repeats (TIRs). MuDR is the autonomous element, and a transcriptionallyactive MuDR is required for transposition of the non-autonomous Mu elements (Chomet et al.,1991). MuDR contains two genes, mudrA and mudrB (Figure 1A); mudrA encodes the MURAtransposase, and mudrB encodes a protein with unknown function. To avoid the deleterious effects of transposons, plants have acquired mechanisms to epigenetically silence them. Silenced Mu elements become heavily methylated, and their reactivation is very rare. To date, only UV-B radiation treatments have reactivated silenced Mu (Walbot 1999). We previously demonstrated that UV-B radiation modifies the chromatin at MuDR/Mu loci, triggering the expression of the transposase (Questa et al., 2010). MURA transposase interacts in vitro with a 32 bp domain, highly conserved in all mobile Mu TIRs (Benito and Walbot 1997). Furthermore, MURA can bind unmethylated, methylated and hemimethylated forms of its target sequence, therefore, the production of MURA is the rate-limiting step in reactivation of silent Mu elements. In the present work, we aim to elucidate the in vivo binding of MURA to its target sequence, and whether this interaction is affected by UV-B radiation.Fil: Qüesta, Julia I.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); ArgentinaFil: Walbot, Virginia. University Of Stanford; Estados UnidosFil: Casati, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentin

Is winter coming? Impact of the changing climate on plant responses to cold temperature

Climate change is causing alterations in annual temperature regimes worldwide. Important aspects of this include the reduction of winter chilling temperatures as well as the occurrence of unpredicted frosts, both significantly affecting plant growth and yields. Recent studies advanced the knowledge of the mechanisms underlying cold responses and tolerance in the model plant Arabidopsis thaliana. However, how these cold-responsive pathways will readjust to ongoing seasonal temperature variation caused by global warming remains an open question. In this review, we highlight the plant developmental programmes that depend on cold temperature. We focus on the molecular mechanisms that plants have evolved to adjust their development and stress responses upon exposure to cold. Covering both genetic and epigenetic aspects, we present the latest insights into how alternative splicing, noncoding RNAs and the formation of biomolecular condensates play key roles in the regulation of cold responses. We conclude by commenting on attractive targets to accelerate the breeding of increased cold tolerance, bringing up biotechnological tools that might assist in overcoming current limitations. Our aim is to guide the reflection on the current agricultural challenges imposed by a changing climate and to provide useful information for improving plant resilience to unpredictable cold regimes.This work was supported by the Junior Leader Fellowship (LCF/BQ/PI19/11690003) from “laCaixa” Foundation (ID100010434) awarded to Julia I. Qüesta and from MCIN/AEI “PID2019-110510GA-I00”/10.13039/501100011033. Alvaro Santiago Larran has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 945043. Work at CRAG was also supported by grant no. SEV-2015-0533 funded by MCIN/AEI/10.13039/501100011033, and by the CERCA Programme/Generalitat de Catalunya. Alice Pajoro receives funding from the Italian Ministry of University and Research (MUR) in the PRIN2020 scheme (Prot. 2020RX4NWM), from Regione Lazio under the POR-FERS project Top of the Crop (A0375-2020-36731) and from the Max-Planck Society as leader of a Max-Planck Partner group. Alice Pajoro is supported by the Deutsche Forschungsgemeinschaft (DFG) through Cluster of Excellence CEPLAS (EXC 2048/1 Project ID: 390686111).Peer reviewe