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.
A genome-wide survey identified 217 EXO70 genes across five kiwifruit (Actinidia spp.) species, classifying them into three subfamilies and nine clades and revealing lineage‑specific expansions, especially in EXO70C, EXO70E, and EXO70H. Functional assays demonstrated that kiwifruit EXO70B1 interacts with the immune hub protein RIN4_1, suggesting a conserved EXO70‑RIN4 module in plant immunity. The study provides a foundational resource for exploring EXO70‑mediated disease resistance in kiwifruit.
The study reveals that the energy sensor SnRK1 modulates Arabidopsis defense by repressing SA‑dependent gene expression and bacterial resistance, with its activity enhanced under high humidity. SnRK1 interacts with TGA transcription factors to attenuate PR1 expression, linking cellular energy status to immune regulation.
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.
NUDIX Hydrolases Target Specific Inositol Pyrophosphates and Regulate Phosphate Homeostasis and Bacterial Pathogen Susceptibility in Arabidopsis
Authors: Schneider, R., Lami, K., Prucker, I., Stolze, S. C., Strauss, A., Schmidt, J. M., Bartsch, S. M., Langenbach, K., Lange, E., Ritter, K., Furkert, D., Faiss, N., Kumar, S., Hasan, M. S., Makris, A., Krusenbaum, L., Wege, S., Belay, Y. Z., Kriescher, S., The, J., Harings, M., Grundler, F., Ried-Lasi, M. K., Schoof, H., Gaugler, P., Kamleitner, M., Fiedler, D., Nakagami, H., Giehl, R. F., Lahaye, T., Bhattacharjee, S., Jessen, H. J., Gaugler, V., Schaaf, G.
The study identified two subclades of Arabidopsis NUDIX hydrolases that selectively hydrolyze distinct inositol pyrophosphate isomers, with subclade I targeting 4-InsP7 and subclade II targeting 3-InsP7 in a Mg2+-dependent manner. Loss-of-function mutants of subclade II NUDTs displayed disrupted phosphate and iron homeostasis, elevated 1/3-InsP7 levels, and increased resistance to Pseudomonas syringae, revealing roles in nutrient signaling and plant immunity, while cross-kingdom analyses showed conserved PP-InsP‑metabolizing activities.
The study used single‑cell transcriptomics to compare Arabidopsis thaliana leaf cell responses during pattern‑triggered and effector‑triggered immunity, revealing that core defense modules are broadly shared but differ in timing, intensity, and cell‑type specific receptor dynamics. Distinct mesophyll subpopulations showed divergent resilience patterns, and gene regulatory network analysis identified WRKY‑regulated and salicylic‑acid biosynthesis modules, with the cue1-6 mutant confirming robustness of core immune responses while exposing cryptic sucrose‑responsive pathways.
The study reveals that a conserved clade of pentatricopeptide repeat (PPR) genes in Arabidopsis thaliana generates secondary siRNAs that contribute to plant immunity, with these PPR loci undergoing extensive duplication and diversification to create a varied siRNA pool for pathogen defense. This PPR‑siRNA system is proposed as a novel family of defense genes with potential for engineering broad‑spectrum disease resistance.