Genomic and Epigenomic Changes in the Progeny of Cold-Stressed Arabidopsis thaliana Plants

Role of epigenetics in mangroves: recent progress and future perspectives

Epigenetic modifications in plants involve heritable changes in gene expression patterns that are not due to changes in gene sequences. Unlike genetic adaptations, which are long-term evolutionary changes, epigenetic modifications, such as DNA methylation, histone modifications, and noncoding RNAs, act as adaptive responses and allow plants to better cope with environmental stresses. As mangroves are uniquely located between the land and sea and remain continuously exposed to varying salinity, submergence, and hypoxia stresses, it is expected that certain epigenetic mechanisms might help them withstand the impacts of recurring stress fluctuations. Therefore, understanding the role of epigenetic regulation in mangrove stress adaptations to the intertidal environment is crucial. Despite only few studies to date having investigated epigenetic responses in mangroves, they nonetheless provide important insights into this process on which to base future research. Here, we present an update on recent progress in mangrove epigenetic research and offer perspectives on the potential roles of various epigenetic players in mangrove adaptations to the intertidal environment.

Genetic and Epigenetic Changes in Arabidopsis thaliana Exposed to Ultraviolet-C Radiation Stress for 25 Generations

Continuous exposure to stress contributes to species diversity and drives microevolutionary processes. It is still unclear, however, whether epigenetic changes, in the form of epimutations such as, for example, differential DNA methylation, are the pre-requisite to speciation events. We hypothesized that continuous stress exposure would increase epigenetic diversity to a higher extent than genetic diversity. In this work, we have analyzed the effect of 25 consecutive generations of UV-C-stress exposure on the Arabidopsis thaliana genome and epigenome. We found no evidence of increased tolerance to UV-C in the progeny of UV-C-stressed plants (F25UV) as compared to the progeny of control plants (F25C). Genetic analysis showed an increased number of single nucleotide polymorphisms (SNPs) and deletions in F25UV plants. Most common SNPs were mutations in cytosines, C to T, C to A, and C to G. Analysis of cytosine methylation showed a significant increase in the percentage of methylated cytosines at CG context in F25UV as compared to F25C or F2C (parental control). The most significant differences between F25UV and either control group were observed in CHG and CHH contexts; the number of hypomethylated cytosines at CHH contexts was over 10 times higher in the F25UC group. F25UV plants clustered separately from other groups in both genomic and epigenomic analyses. GO term analysis of differentially methylated genes revealed enrichments in "DNA or RNA metabolism", "response to stress", "response to biotic and abiotic stimulus", and "signal transduction". Our work thus demonstrates that continuous exposure to UV-C increases genomic and epigenomic diversity in the progeny, with epigenetic changes occurring in many stress-responsive pathways.