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 isolated an endophytic Pseudomonas aeruginosa strain (SPT08) from tomato cotyledon seedlings that suppressed the wilt pathogen Ralstonia pseudosolanacearum and promoted plant growth, increasing height by 20% and root biomass by 60%. GFP labeling confirmed endophytic colonization, and genomic analysis revealed multiple secretion systems and secondary‑metabolite gene clusters associated with biocontrol and growth‑promoting traits.
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.
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.
Introducing furanocoumarin biosynthetic genes in tomato results in coumarins accumulation and impacted growth
Authors: Bouille, A., Villard, C., Galati, G., Roumani, M., Fauvet, A., Grosjean, J., Hoengenaert, L., Boerjan, W., Ralph, J., Hilliou, F., Robin, C., Hehn, A., Larbat, R.
The study engineered the linear furanocoumarin pathway in tomato by integrating four biosynthetic genes, aiming to produce psoralen, but instead generated coumarins such as scopoletin. Morphophysiological, metabolomic, and transcriptomic analyses revealed that even low levels of these coumarins can influence plant growth and physiology, highlighting both benefits and costs of coumarin accumulation in crops.
The study investigates hormetic responses of tomato (Solanum lycopersicum) seedlings to low‑dose cadmium, demonstrating enhanced growth through morphological, biochemical, and histochemical analyses. Transcriptomic profiling revealed differential expression of oxidoreductase genes, signaling components, and several long non‑coding RNAs (lncRNAs) that generate miRNAs (sly‑MIR396a and sly‑MIR1063g), which modulate target genes to promote growth. In‑silico analyses of lncRNA targets and miRNA precursors provide mechanistic insight into cadmium‑induced hormesis and its potential for crop improvement.
Tomato leaf transcriptomic changes promoted by long-term water scarcity stress can be largely prevented by a fungal-based biostimulant
Authors: Lopez-Serrano, L., Ferez-Gomez, A., Romero-Aranda, R., Jaime Fernandez, E., Leal Lopez, J., Fernandez Baroja, E., Almagro, G., Dolezal, K., Novak, O., Diaz, L., Bautista, R., Leon Morcillo, R. J., Pozueta Romero, J.
Foliar application of Trichoderma harzianum cell‑free culture filtrates (CF) increased fruit yield, root growth, and photosynthesis in a commercial tomato cultivar under prolonged water deficit in a Mediterranean greenhouse. Integrated physiological, metabolite, and transcriptomic analyses revealed that CF mitigated drought‑induced changes, suppressing about half of water‑stress responsive genes, thereby reducing the plant’s transcriptional sensitivity to water scarcity.
The study profiled root transcriptomes of Arabidopsis wild type and etr1 gain-of-function (etr1-3) and loss-of-function (etr1-7) mutants under ethylene or ACC treatment, identifying 4,522 ethylene‑responsive transcripts, including 553 that depend on ETR1 activity. ETR1‑dependent genes encompassed ethylene biosynthesis enzymes (ACO2, ACO3) and transcription factors, whose expression was further examined in an ein3eil1 background, revealing that both ETR1 and EIN3/EIL1 pathways regulate parts of the network controlling root hair proliferation and lateral root formation.
Exogenous Hormone Treatments Reveal Species-Specific Regulation of Individual Components of Root Architecture and Salt Ion Accumulation in Cultivated and Wild Tomatoes
Authors: Rahmati-Ishka, M., Craft, E., Pineros, M., Julkowska, M. M.
The study examined how individual hormone treatments (auxin, ethylene, gibberellin) influence root architecture and ion accumulation under salt stress in three tomato accessions, revealing species-specific hormonal effects on lateral root development and Na/K ratios. Genetic analyses using Arabidopsis mutants and a tomato ethylene‑perception mutant (nr) identified novel hormonal signaling components that modulate salt stress responses, highlighting potential strategies to improve crop performance.