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 identified a heat‑responsive exon‑skipping event in the basic Helix‑Loop‑Helix domain of the transcription factor PIF4, which reduces PIF4 activity and promotes photomorphogenic traits in etiolated seedlings. This reveals a novel post‑transcriptional mechanism by which plants modulate PIF4 function during heat stress.
In vivo binding by Arabidopsis SPLICING FACTOR 1 shifts 3' splice site choice, regulating circadian rhythms and immunity in plants
Authors: Agrofoglio, Y. C., Iglesias, M. J., de Leone, M. J., Hernando, C. E., Lewinski, M., Torres, S. B., Contino, G., Yanovsky, M. J., Staiger, D., Mateos, J. L.
The study characterizes the plant spliceosomal protein AtSF1 in Arabidopsis thaliana, using iCLIP and RNA‑seq to map its in vivo branch point binding sites and demonstrate that loss of AtSF1 causes widespread 3' splice‑site mis‑selection. Structural comparison reveals a plant‑specific domain architecture, and the identified AtSF1 targets are enriched for circadian and defense genes, linking splicing regulation to timing and immunity.
Using a forward genetic screen of 284 Arabidopsis thaliana accessions, the study identified extensive natural variation in root endodermal suberin and pinpointed the previously unknown gene SUBER GENE1 (SBG1) as a key regulator. GWAS and protein interaction analyses revealed that SBG1 controls suberin deposition by binding type‑one protein phosphatases (TOPPs), with disruption of this interaction or TOPP loss‑of‑function altering suberin levels, linking the pathway to ABA signaling.
Splicing regulation by RS2Z36 controls ovary patterning and fruit growth in tomato
Authors: Vraggalas, S., Rosenkranz, R. R., Keller, M., Perez-Perez, Y., Bachiri, S., Zehl, K., Bold, J., Simm, S., Ghatak, A., Weckwerth, W., Afjehi-Sadat, L., Chaturvedi, P., Testillano, P. S., Mueller-McNicoll, M., Zarnack, K., Fragkostefanakis, S.
The study identifies the serine/arginine-rich splicing factor RS2Z36 as a key regulator of ovary patterning and early fruit morphology in tomato, with loss‑of‑function mutants producing smaller, ellipsoid fruits and elongated pericarp cells. RNA‑seq and proteomic analyses reveal widespread alternative splicing and altered protein abundance, including novel splice‑variant peptides, while mutant pericarps show increased deposition of LM6‑detected arabinan and AGP epitopes.
The study functionally characterizes a conserved structured RNA motif (45ABC) in Arabidopsis RBP45 pre‑mRNAs, showing that its sequence and pairing elements mediate a negative auto‑ and cross‑regulatory feedback loop through alternative splicing that produces unproductive isoforms and reduces RBP45 expression. Transcriptome‑wide splicing analysis and phenotypic assessment of rbp45 mutants reveal that RBP45B plays a dominant role and that proper regulation of this motif is essential for root growth and flowering time.
Integrating physiological, transcriptomic, and cellular analyses, the study shows that olive fruit abscission zones undergo lignification, alkalization, and extensive cell‑wall remodeling during natural maturation and after ethephon treatment. A set of 733 FAZ‑specific genes, including β‑1,3‑glucanases, pectate lyases, and pH‑regulating transporters, were identified, and increased glucanase activity together with reduced plasmodesmata callose suggest enhanced intercellular communication facilitates organ detachment in this non‑climacteric fruit.
The study combined high-throughput image-based phenotyping with genome-wide association studies to uncover the genetic architecture of tolerance to the spittlebug Aeneolamia varia in 339 interspecific Urochloa hybrids. Six robust QTL were identified for plant damage traits, explaining up to 21.5% of variance, and candidate genes linked to hormone signaling, oxidative stress, and cell‑wall modification were highlighted, providing markers for breeding.
The study investigates how the timing of the vegetative phase change (VPC) in Arabidopsis thaliana influences drought adaptation, revealing strong genotype-by-environment interactions that create stage-specific fitness tradeoffs. Genotypes from warmer, drier Iberian climates transition earlier, and genome-wide association mapping identifies loci linked to VPC timing and drought response, with several candidates validated using T‑DNA insertion lines.
A large-scale proteomic study in Arabidopsis thaliana identified over 32,000 isoform-specific peptides, confirming that alternative splicing, particularly intron retention, produces translated protein isoforms. Integrated proteogenomic analysis, SUPPA classification, and AlphaFold modeling revealed structural impacts and a non-linear regulation of transcript and protein abundance, with mutant phenotypes linking splicing to growth, chlorophyll content, and anthocyanin accumulation.