Molecular and Phenotypic Characterization of Telomere Repeat Binding (TRBs) Proteins in Moss: Evolutionary and Functional Perspectives
Authors: Kusova, A., Hola, M., Goffova Petrova, I., Rudolf, J., Zachova, D., Skalak, J., Hejatko, J., Klodova, B., Prerovska, T., Lycka, M., Sykorova, E., Bertrand, Y. J. K., Fajkus, J., Honys, D., Prochazkova Schrumpfova, P.
The study characterizes telomere repeat binding (TRB) proteins in the model moss Physcomitrium patens, demonstrating that individual PpTRB genes are essential for normal protonemal and gametophore development and that loss of TRBs leads to telomere shortening, mirroring findings in seed plants. Transcriptome analysis of TRB mutants shows altered expression of genes linked to transcription regulation and stimulus response, while subcellular localization confirms nuclear residence and mutual interaction of PpTRBs, underscoring their conserved role in telomere maintenance across land plants.
The study introduced full-length SOC1 genes from maize and soybean, and a partial SOC1 gene from blueberry, into tomato plants under constitutive promoters. While VcSOC1K and ZmSOC1 accelerated flowering, all three transgenes increased fruit number per plant mainly by promoting branching, and transcriptomic profiling revealed alterations in flowering, growth, and stress‑response pathways.
The study used phospho‑proteomics to uncover rapid phosphorylation changes in Arabidopsis seedlings upon light or sucrose exposure, identifying RS41 as a hyperphosphorylated SR protein. By creating single and higher‑order mutants of four RS genes, the authors demonstrated that these RS proteins are essential for photomorphogenic development and regulate light‑dependent alternative splicing, with loss of all four causing sterility.
The study characterizes the distinct and overlapping roles of the rice PI paralogs OsMADS2 and OsMADS4 in lodicule specification, flowering time, and floral organ development by analyzing null and double mutants and overexpression lines. Genome-wide binding (ChIP‑seq) and transcriptome (RNA‑seq) analyses identified downstream targets involved in cell division, cell wall remodeling, and osmotic regulation that underpin the observed phenotypes. These findings reveal novel functions for PI paralogs in reproductive development and highlight mechanisms of transcription factor diversification in Oryza sativa.
The study investigated how Arabidopsis thaliana SR protein kinases (AtSRPKs) regulate alternative RNA splicing by using chemical inhibitors of SRPK activity. Inhibition with SPHINX31 and SRPIN340 caused reduced root growth and loss of root hairs, accompanied by widespread changes in splicing and phosphorylation of genes linked to root development and other cellular processes. Multi‑omics analysis (transcriptomics and phosphoproteomics) revealed that AtSRPKs modulate diverse splicing factors and affect the splicing landscape of numerous pathways.
The study used TurboID-based proximity labeling coupled with mass spectrometry to map the Arabidopsis alternative splicing machinery centered on ACINUS, PININ, and SR45, identifying 298 high-confidence components and revealing that splicing is tightly linked to transcription and other RNA processing steps. Bioinformatic and genetic analyses, including O-glycosylation double mutants, demonstrated both conserved and plant‑specific regulatory networks and highlighted the role of sugar modifications in modulating splicing.
The study investigates the role of the Arabidopsis transcription factor AtMYB93 in sulfur (S) signaling and root development, revealing that AtMYB93 mutants exhibit altered expression of S transport and metabolism genes and increased shoot S levels, while tomato plants overexpressing SlMYB93 show reduced shoot S. Transcriptomic profiling, elemental analysis, and promoter activity assays indicate that AtMYB93 contributes to root responses to S deprivation, though functional redundancy masks clear phenotypic effects on lateral and adventitious root formation.
The study investigates the Arabidopsis ribosomal protein RPS6A and its role in auxin‑related root growth, revealing that rps6a mutants display shortened primary roots, fewer lateral roots, and defective vasculature that are not rescued by exogenous auxin. Cell biological observations and global transcriptome profiling show weakened auxin signaling and reduced levels of PIN auxin transporters in the mutant, indicating a non‑canonical function of the ribosomal subunit in auxin pathways.
The study demonstrates that abscisic acid (ABA) accumulates in darkness to suppress cotyledon opening during seedling deetiolation, and that light exposure lifts this repression, enabling cotyledon aperture. Genome‑wide transcriptional and alternative‑splicing changes accompany this process, and the light‑dependent regulation requires the splicing factors RS40 and RS41, whose activity is repressed in the dark.