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 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 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 shows that silencing of NOR2 rRNA genes in Arabidopsis thaliana depends primarily on CHH-context cytosine methylation, particularly mediated by CMT2 and the chromatin remodeler DDM1, rather than CG or CHG methylation. Comparative promoter analysis revealed a prevalence of CHH sites in plant rDNA promoters, explaining why CHH methylation mutants disrupt NOR2 silencing more strongly, while NOR2 loci are hyper‑methylated and more condensed than NOR4.