Epigenetics
The intimate linkage between H3K36me3 and m6A modifications has been demonstrated in mammals. In this issue, Shim et al. (2020) show that similar crosstalk between histone modification and mRNA methylation is conserved in plants, but H3K36me2 is more important for m6A deposition in plants.
Many over‐wintering plants, through vernalization, overcome a block to flowering and thus acquire competence to flower in the following spring after experiencing prolonged cold exposure or winter cold. The vernalization pathways in different angiosperm lineages appear to have convergently evolved to adapt to temperate climates. Molecular and epigenetic mechanisms for vernalization regulation have been well studied in the crucifer model plant Arabidopsis thaliana. Here, we review recent progresses on the vernalization pathway in Arabidopsis. In addition, we summarize current molecular and genetic understandings of vernalization regulation in temperate grasses including wheat and Brachypodium, two monocots from Pooideae, followed by a brief discussion on divergence of the vernalization pathways between Brassicaceae and Pooideae.
DNA methylation is a conserved and important epigenetic mark in both mammals and plants. DNA methylation can be dynamically established, maintained, and removed through different pathways. In plants, active DNA demethylation is initiated by the RELEASE OF SILENCING 1 (ROS1) family of bifunctional DNA glycosylases/lyases. Accumulating evidence suggests that DNA demethylation is important in many processes in plants. In this review, we summarize recent studies on the enzymes and regulatory factors that have been identified in the DNA demethylation pathway. We also review the functions of active DNA demethylation in plant development as well as biotic and abiotic stress responses. Finally, we highlight those aspects of DNA demethylation that require additional research.
Thousands of differentially expressed genes (DEGs) have been identified in rice under drought stress conditions. However, the regulatory mechanism of these DEGs remains largely unclear. Here, we report an interplay between histone H3K4me3 modification and transcription factor OsbZIP23 in the regulation of a dehydrin gene cluster under drought stress conditions in rice. When the H3K4me3 modification level was increased, the dehydrin gene expression levels were increased, and the binding levels of OsbZIP23 to the promoter of the dehydrin genes were also enhanced. Conversely, the H3K4me3 modification and dehydrin gene expression levels were downregulated in the osbzip23 mutant under drought stress conditions. Our study uncovers a collaboration between transcription factor and H3K4me3 modification in the regulation of drought‐responsive genes, which will help us to further understand the gene regulation mechanism under stress conditions in plants.