Root-Suppressed Phenotype of Tomato Rs Mutant is Seemingly Related to Expression of Root-Meristem-Specific Sulfotransferases
Authors: Kumari, A., Gupta, P., Santisree, P., Pamei, I., Valluri,, S., Sharma, K., Venkateswara Rao, K., Shukla, S., Nama, S., Sreelakshmi, Y., Sharma, R.
The study characterizes a radiation‑induced root‑suppressed (Rs) mutant in tomato that displays dwarfism and pleiotropic defects in leaves, flowers, and fruits. Metabolite profiling and rescue with H2S donors implicate disrupted sulfur metabolism, and whole‑genome sequencing identifies promoter mutations in two root‑meristem‑specific sulfotransferase genes as likely contributors to the root phenotype.
An ancient alkalinization factor informs Arabidopsis root development
Authors: Xhelilaj, K., von Arx, M., Biermann, D., Parvanov, A., Faiss, N., Monte, I., Klingelhuber, F., Zipfel, C., Timmermans, M., Oecking, C., Gronnier, J.
The study identifies members of the REMORIN protein family as inhibitors of plasma membrane H⁺‑ATPases, leading to extracellular pH alkalinization that modulates cell surface processes such as steroid hormone signaling and coordinates root developmental transitions in Arabidopsis thaliana. This inhibition represents an ancient mechanism predating root evolution, suggesting that extracellular pH patterning has shaped plant morphogenesis.
The study examined how DNA methylation influences cold stress priming in Arabidopsis thaliana, revealing that primed plants exhibit distinct gene expression and methylation patterns compared to non-primed plants. DNA methylation mutants, especially met1 lacking CG methylation, showed altered cold memory and misregulation of the CBF gene cluster, indicating that methylation ensures transcriptional precision during stress recall.
The authors used a bottom‑up thermodynamic modelling framework to investigate how plants decode calcium signals, starting from Ca2+ binding to EF‑hand proteins and extending to higher‑order decoding modules. They identified six universal Ca2+-decoding modules that can explain variations in calcium sensitivity among kinases and provide a theoretical basis for interpreting calcium signal amplitude and frequency in plant cells.
The histone methyltransferase SDG26 shapes cold stress responses in Arabidopsis through chromatin-based regulation of ABA-dependent and ABA-independent pathways
Authors: Xue, Z., Zumsteg, J., Mathieu, E., Shen, W.-H., Berr, A.
The study identifies the histone methyltransferase SDG26 as a positive regulator of cold stress responses in Arabidopsis thaliana, showing that it is induced by cold and promotes expression of CBF‑COR genes via H3K36me3 deposition. Loss of SDG26 enhances freezing tolerance but compromises drought tolerance by affecting ABA biosynthesis and stomatal closure, indicating that SDG26 integrates ABA‑dependent and independent pathways to balance cold acclimation with water conservation.
A diverse rice germplasm panel was screened for cold tolerance at seedling and reproductive stages using artificial cold-water tanks, natural field conditions, and controlled cold facilities, with performance evaluated via quantitative and qualitative traits. Several genotypes displayed stage-specific or combined tolerance, while others were consistently vulnerable, and PCA indicated overlapping yet distinct physiological mechanisms across environments, supporting the existence of stage-specific QTLs for cold resistance.
The study reveals that the cold‑repressed transcription factor MtCBF4 suppresses anthocyanin synthesis in Medicago truncatula by repressing MtLAP1 and modulating histone H3K27 trimethylation via activation of the demethylase MtJMJ13. MtJMJ13, in turn, demethylates the gene bodies of MtCBF4 and other negative regulators, creating a feedback loop that is inhibited under cold stress, thereby increasing anthocyanin accumulation and enhancing cold tolerance. This work identifies a transcription‑epigenetic regulatory module controlling anthocyanin production during cold stress.
The study used RNA‑seq to compare early transcriptional responses to acute heat and cold stress in cultivated cranberry (Vaccinium macrocarpon) and its F1 hybrids with the cold‑adapted wild relative V. oxycoccos. Cold stress triggered differential expression in pathways such as photosynthesis, ribosomes, defense, and hormone signaling, with some hybrids showing transiently elevated cold‑responsive expression, suggesting potential cold‑tolerance introgression. The results highlight the utility of wild germplasm for breeding temperature‑resilient cranberries.
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.
The authors examined how the long non-coding RNAs SVALKA (SVK) and SVALNA (SVN) regulate the cold‑responsive transcription factors CBF1 and CBF3 in Arabidopsis thaliana. Using native elongation transcript sequencing, CRISPR‑Cas9 deletions, and RT‑qPCR, they showed that SVK acts both in cis and trans through RNAPII collision and chromatin remodeling, while SVN acts cis‑negatively via RNAPII collision, with isoform diversity generated by alternative splicing being critical for function.