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.
The study identifies two diel regulatory modules that coordinate plant cuticle formation: the LRB‑phyB‑PIF4 pathway suppresses wax biosynthesis during daylight, while the COP1‑CFLAP1 pathway promotes cutin accumulation at night. Degradation of phyB and CFLAP1 via specific E3 ubiquitin ligases modulates the activity of transcription factors PIF4 and BDG1 to ensure timely cuticle assembly.
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.
The study shows that high ambient temperature triggers extensive changes in ROS homeostasis in Arabidopsis seedlings, with H2O2 balance being essential for thermomorphogenic hypocotyl elongation. PIF4 directly activates catalase genes CAT2 and CAT3 to regulate H2O2 levels, forming a PIF4‑CAT‑H2O2 module that operates alongside the PIF4‑auxin pathway, while elevated H2O2 feeds back to reduce PIF4 protein abundance.
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 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 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 demonstrates that the microtubule‑associated protein WDL4 is essential for PhyB‑dependent thermomorphogenic and photomorphogenic responses in Arabidopsis, as wdl4-3 mutants mimic phyB loss‑of‑function phenotypes under varying temperatures and light conditions. Genetic analyses reveal that PIF4 activity is required for wdl4-3 hypocotyl hyper‑elongation, and while exogenous auxin can rescue pif4‑related defects, it does not restore the wdl4-3 specific elongation, indicating additional regulatory layers.
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.