Nanoclustering of a plant transcription factor enables strong yet specific DNA binding
Authors: Arfman, K., Janssen, B. P. J., Romein, R., van den Boom, S., van der Woude, M., Jansen, L., Rademaker, M., Hernandez-Garcia, J., Ramalho, J. J., Dipp-Alvarez, M., Borst, J. W., Weijers, D., van Mierlo, C. P. M., Sprakel, J.
The study reveals that the Auxin Response Factor MpARF2 in Marchantia polymorpha forms nanoscopic clusters within the plant nucleus, representing a distinct mode of DNA binding distinct from monomeric/oligomeric binding and liquid phase-separated condensates. These nanoclusters provide high‑affinity, switch‑like, sequence‑specific DNA interaction, suggesting a novel mechanism for transcriptional regulation by TF nanoclustering.
The study reveals that in the liverwort Marchantia polymorpha, the UV‑B photoreceptor MpUVR8 forms homodimers that monomerize and accumulate in the nucleus upon UV‑B exposure, activating COP1‑dependent growth inhibition, gene expression reprogramming, and UV‑absorbing metabolite production. MpRUP promotes redimerization of MpUVR8, acting as a negative regulator, while MpSPA also negatively modulates UVR8 signaling, indicating lineage‑specific diversification of UV‑B signaling components that originated over 400 Myr ago.
The study investigates the role of the chromatin regulator MpSWI3, a core subunit of the SWI/SNF complex, in the liverwort Marchantia polymorpha. A promoter mutation disrupts male gametangiophore development and spermiogenesis, causing enhanced vegetative propagation, and transcriptomic analysis reveals that MpSWI3 regulates genes controlling reproductive initiation, sperm function, and asexual reproduction, highlighting its ancient epigenetic role in balancing vegetative and reproductive phases.
The study investigates the role of two ATP-binding cassette transporters, MpABCG1 and MpABCG36, in the sequestration of specialized metabolites within oil bodies of the liverwort Marchantia polymorpha. Loss‑of‑function mutants displayed reduced accumulation of sesquiterpenes and, specifically for MpABCG1, decreased levels of bis‑bibenzyls, while oil‑body formation remained largely unaffected, indicating these transporters are essential for metabolite accumulation rather than organelle biogenesis.
The study demonstrates that limonene, a natural essential‑oil component, strongly inhibits Fusarium oxysporum, the causal agent of potato dry rot, by impairing colony growth, hyphal morphology, spore viability, membrane integrity, and transcription/translation processes, as well as disrupting ion homeostasis. Combined treatments reveal additive effects with mancozeb and synergistic effects with hymexazol, highlighting limonene's potential as an eco‑friendly bio‑fungicide for potato disease management.
The study characterizes the single-copy S-nitrosoglutathione reductase 1 (MpGSNOR1) in the liverwort Marchantia polymorpha, showing that loss-of-function mutants generated via CRISPR/Cas9 exhibit marked morphological defects and compromised SNO homeostasis and immune responses. These findings indicate that GSNOR-mediated regulation of S‑nitrosylation is an ancient mechanism linking development and immunity in early land plants.
The study examines how proteasomal degradation of A‑class and B‑class Auxin Response Factors (ARFs) is regulated in the bryophyte Marchantia polymorpha, identifying a key residue required for MpARF2 degradation that is also conserved in MpARF1. While disruption of MpARF2 degradation impairs development across life‑cycle stages, blocking MpARF1 degradation has minimal phenotypic impact, indicating divergent functional integration despite a shared degradation mechanism.
Gain and loss of gene function shaped the nickel hyperaccumulation trait in Noccaea caerulescens
Authors: Belloeil, C., Garcia de la Torre, V. S., Contreras Aguilera, R., Kupper, H., Lopez-Roques, C., Iampetro, C., Vandecasteele, C., Klopp, C., Launay-Avon, A., Leemhuis, W., Yamjabok, J., van den Heuvel, J., Aarts, M. G. M., Quintela Sabaris, C., Thomine, S., MERLOT, S.
The study presents a high-quality genome assembly for the nickel hyperaccumulator Noccaea caerulescens and uses it as a reference for comparative transcriptomic analyses across different N. caerulescens accessions and the non‑accumulating relative Microthlaspi perfoliatum. It identifies a limited set of metal transporters (NcHMA3, NcHMA4, NcIREG2, and NcIRT1) whose elevated expression correlates with hyperaccumulation, and demonstrates that frameshift mutations in NcIRT1 can abolish the trait, indicating an ancient, transporter‑driven origin of nickel hyperaccumulation.
The study integrates genome, transcriptome, and chromatin accessibility data from 380 soybean accessions to dissect the genetic and regulatory basis of symbiotic nitrogen fixation (SNF). Using GWAS, TWAS, eQTL mapping, and ATAC-seq, the authors identify key loci, co‑expression modules, and regulatory elements, and validate the circadian clock gene GmLHY1b as a negative regulator of nodulation via CRISPR and CUT&Tag. These resources illuminate SNF networks and provide a foundation for soybean improvement.
MdBRC1 and MdFT2 Interaction Fine-Tunes Bud Break Regulation in Apple
Authors: Gioppato, H. A., Estevan, J., Al Bolbol, M., Soriano, A., Garighan, J., Jeong, K., Georget, C., Soto, D. G., El Khoury, S., Falavigna, V. d. S., George, S., Perales, M., Andres, F.
The study identifies the transcription factor MdBRC1 as a key inhibitor of bud growth during the ecodormancy phase in apple (Malus domestica), directly regulating dormancy‑associated genes and interacting with the flowering promoter MdFT2 to modulate bud break. Comparative transcriptomic analysis and gain‑of‑function experiments in poplar demonstrate that MdFT2 physically binds MdBRC1, attenuating its repressive activity and acting as a molecular switch for the transition to active growth.