Genetius

The study examined the roles of AtKUP2, AtKUP6, AtKUP8, and GORK potassium transport proteins in guard cell function by performing gas-exchange measurements on mature Arabidopsis leaves. Loss of KUP2/6/8 reduced stomatal conductance, whereas a GORK loss‑of‑function mutant showed increased conductance, yet the magnitude of light‑ and ABA‑induced transpiration changes remained similar across genotypes, suggesting a limited dynamic range for rapid stomatal movements that relies on small ionic osmolytes.

The study shows that Arabidopsis root tips adapt to hypoxia by increasing H3K4me3 levels, linked to the inhibition of group 7 demethylases (KDM7s). Genetic loss of KDM7s mimics hypoxic conditions, activating genes that sustain meristem survival, suggesting KDM7s act as root‑specific oxygen sensors that prime epigenetic tolerance mechanisms.

The study reveals that the methyl‑CpG‑binding domain protein MBD8 interacts with the histone demethylase LDL2 to facilitate removal of H3K4me1 and transcriptional repression downstream of H3K9me2 in Arabidopsis. MBD8 binds GC‑poor DNA independently of cytosine methylation and stabilizes LDL2 protein levels, indicating a broader role for MBD proteins beyond methyl‑DNA recognition.

The study used chemically induced effector-triggered immunity combined with single-cell transcriptomics to map immune responses across all leaf cell types in Arabidopsis, revealing that while a core defense program is universally activated, individual cell types deploy distinct transcriptional modules. Functional assays showed that epidermis‑specific transcriptional regulators are essential for preventing pathogen penetration, indicating a spatial division of immune functions within the leaf.

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 uses time-course microscopy to show that VAR2 mutants have delayed and heterogeneous chloroplast biogenesis, with many cells lacking chloroplasts, especially in white leaf sectors. Genetic interactions reveal that loss of plastid division genes worsens the phenotype, while overexpressing PDV1/PDV2 or knocking out COP1 rescues it, indicating VAR2’s novel role in plastid division and chloroplast development. These findings clarify mechanisms behind leaf variegation.

The study identifies the scaffolding protein RACK1A as a cytoplasmic interaction partner of the antioxidant enzyme FSD1, revealing that RACK1A recruits FSD1 to cycloheximide-sensitive condensates that colocalize with stress granules during salt stress. Functional analyses show that this RACK1A‑FSD1 module modulates ROS levels, influences root hair tip growth, and determines salt‑stress resilience in Arabidopsis.

The study identifies four Arabidopsis REM transcription factors (VDD, VAL, REM12, REM13) that bind specific DNA sequences and, together with GDE1, recruit RNA polymerase IV to produce 24‑nt siRNAs that direct DNA methylation at designated loci. Loss of GDE1 causes Pol IV complexes to relocalize to sites bound by REM8, indicating that REM proteins provide sequence‑specific cues for epigenetic patterning.