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 investigates how the pleiotropic maize genes GRASSY TILLERS1 (GT1) and RAMOSA3 (RA3) are differentially regulated to suppress axillary meristems and floral organs, using a newly developed high-throughput quantitative phenotyping method for grass flowers. Distinct environmental mechanisms were found to control each suppression process, and upstream regulatory pathways of GT1 and RA3 have diverged, illustrating how ancient developmental genes can be redeployed to increase genetic pleiotropy during evolution.
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.
Non-catalytic and catalytic TREHALOSE-6-PHOSPHATE SYNTHASES interact with RAMOSA3 to control maize development.
Authors: Tran, T., Claeys, H., Abraham Juarez, M. J., Vi, L. S., Xu, X., Michalski, K., Chou, T. H., Iohannes, S. D., Boumpas, P., Williams, Z., Sheppard, S., Griffiths, C., Paul, M., Furukawa, H., Jackson, D.
The study reveals that the maize catalytic trehalose-6-phosphate phosphatase RA3 interacts with the non‑catalytic TPS ZmTPS1, and together with the catalytic TPS ZmTPS14 they form a protein complex that enhances enzymatic activity. Genetic analyses show that mutations in ZmTPS1 and its paralog ZmTPS12 exacerbate ra3 branching phenotypes, while loss of the catalytic TPSs ZmTPS11 and ZmTPS14 causes embryonic lethality, indicating essential and regulatory roles for both catalytic and non‑catalytic TPS/TPP proteins in plant development.
Using CRISPR‑Cas9‑generated Zmcry mutants, the study shows that maize cryptochromes redundantly mediate blue‑light signaling, suppress mesocotyl elongation, and enhance UV‑B stress tolerance by upregulating genes for phenylpropanoid, flavonoid, and fatty‑acid pathways. Blue light also promotes epidermal wax accumulation, and ZmCRY1 directly interacts with GLOSSY2 in a light‑dependent manner to drive C32 aldehyde synthesis, linking cryptochrome activity to wax biosynthesis and UV‑B resistance.
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.