DECREASE IN DNA METHYLATION 1-mediated epigenetic regulation maintains gene expression balance required for heterosis in Arabidopsis thaliana
Authors: Matsuo, K., Wu, R., Yonechi, H., Murakami, T., Takahashi, S., Kamio, A., Akter, M. A., Kamiya, Y., Nishimura, K., Matsuura, T., Tonosaki, K., Shimizu, M., Ikeda, Y., Kobayashi, H., Seki, M., Dennis, E. S., Fujimoto, R.
The study demonstrates that the chromatin remodeler DDM1 is essential for biomass heterosis in Arabidopsis thaliana hybrids, as loss of DDM1 function leads to reduced rosette growth and extensive genotype‑specific transcriptomic and DNA methylation changes. Whole‑genome bisulfite sequencing revealed widespread hypomethylation in ddm1 mutants, while salicylic acid levels were found unrelated to heterosis, indicating that epigenetic divergence, rather than SA signaling, underpins hybrid vigor.
The study examined molecular responses in grapevine leaves with and without esca symptoms, using metabolite profiling, RNA‑seq and whole‑genome bisulfite sequencing. Metabolic and transcriptomic changes were confined to symptomatic leaves and linked to local DNA‑methylation alterations, while asymptomatic leaves showed distinct but overlapping methylation patterns, some present before symptoms, indicating potential epigenetic biomarkers for early disease detection.
The study identifies GyrB3 as a novel nuclear factor that interacts with histone deacetylases to regulate transposable element silencing in plants, acting as a suppressor of IBM1 deficiency–induced epigenetic defects. Loss of GyrB3 reduces DNA methylation and increases H3 acetylation at TEs, demonstrating the importance of histone deacetylation for genome stability.
Stress-dependent responses of grapevine wood and fungal pathogen activity under esca and drought
Authors: Chambard, M., Cantu, D., Bortolami, G., Dell'Acqua, N., Ferrer, N., Gambetta, G., Garcia, J., Gastou, P., Massonnet, M., Moretti, S., Rochepeau, A., Petriacq, P., Foulongne-Oriol, M., Delmas, C. E. L.
The study used wood metatranscriptomics, metabolomics, and metabarcoding to compare grapevine (Vitis vinifera) responses to drought and esca leaf symptom expression, revealing distinct but overlapping transcriptomic and metabolic signatures, including activation of phenylpropanoid and stilbenoid pathways. Drought reduced esca symptom expression, associated with decreased abundance of the wood‑decay fungus Fomitiporia mediterranea and altered fungal virulence factor expression, while increasing the relative abundance and anti‑oxidative gene expression of Phaeomoniella chlamydospora.
The study investigated whether clonal offspring of Festuca rubra inheriting drought or methyl jasmonate (MeJA) exposure exhibit transgenerational stress memories that enhance tolerance to subsequent drought. Using a factorial experiment, untargeted LC‑MS metabolomics combined with morpho‑physiological assessments revealed that combined drought and MeJA memories generate novel metabolic and physiological responses, improving water conservation and photosynthetic performance. These findings highlight a layered, interactive memory system that can be leveraged to prime drought resilience across generations.
The study examined gene expression, DNA methylation, and small RNA profiles in a Citrus hybrid (C. reticulata × C. australasica) using haplotype‑resolved subgenome assemblies, revealing allele‑specific expression and asymmetric CHH methylation that correlated with increased transcription and 24‑nt siRNA accumulation at promoters. This unconventional association suggests RNA‑directed DNA methylation (RdDM) can activate transcription in citrus fruit and provides a pipeline for epigenomic analysis of complex hybrids relevant to disease resistance breeding.
The study applied a progressive, sublethal drought treatment to Arabidopsis thaliana, collecting time‑resolved phenotypic and transcriptomic data. Machine‑learning analysis revealed distinct drought stages driven by multiple overlapping transcriptional programs that intersect with plant aging, and identified high‑explanatory‑power transcripts as biomarkers rather than causal agents.
Salt stress strongly suppresses root growth in Festuca rubra while sparing shoot development. Transcriptome profiling identified over 68,000 differentially expressed genes, with up‑regulated genes enriched in methionine, melatonin, and suberin biosynthesis and down‑regulated genes involved in gibberellin, ABA, and sugar signaling, indicating extensive hormonal and metabolic reprogramming. Paradoxical regulation of gibberellin and ethylene pathways suggests a finely tuned balance between growth and stress responses.
The study examined how single and repeated mechanical disturbances (whole‑pot drops) affect leaf folding in Mimosa pudica, using chlorophyll fluorescence to track photosystem II efficiency and transcriptome profiling to identify responsive genes. A single drop mainly up‑regulated flavonoid biosynthesis genes, whereas multiple drops triggered broader biotic and abiotic stress pathways, indicating a shift in the plant’s gene regulatory network under repeated stress.
The study conducted tissue-specific metabolomic profiling of leaf, calyx, and fruit surfaces across 29 Physalis species, revealing extensive acylsugar diversity with up to 323 unique structures, many accumulated on fruit surfaces. Hierarchical clustering and phylogenetic analyses showed that acylsugar profiles do not align with taxonomic relationships, and functional assays of ASAT1 enzymes from three species demonstrated broad substrate specificity that likely drives structural variation. These findings highlight fruit-localized acylsugars as potential targets for engineering crop resilience.