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 visualizes subcellular dynamics following activation of the NRC4 resistosome, showing that NRC4 enrichment at the plasma membrane triggers calcium influx, followed by sequential disruption of mitochondria, plastids, endoplasmic reticulum, and cytoskeleton, culminating in plasma membrane rupture and cell death. These observations define a temporally ordered cascade of organelle and membrane events that execute plant immune cell death.
The CATION CALCIUM EXCHANGER 4 (CCX4) regulates LRX1-related root hair development through Ca2+ homeostasis
Authors: Hou, X., Tortora, G., Herger, A., Buratti, S., Dobrev, P. I., Vaculikov, R., Lacek, J., Sotiropoulos, A. G., Kadler, G., Schaufelberger, M., Candeo, A., Bassi, A., Wicker, T., Costa, A., Ringli, C.
The study identified a suppressor mutation (sune42) in the Golgi-localized Ca2+ transporter CCX4 that alleviates the dominant‑negative root hair phenotype caused by the extensin‑less LRX1ΔE14 protein in Arabidopsis. Detailed Ca2+ imaging showed that LRX1ΔE14 disrupts tip‑focused cytoplasmic Ca2+ oscillations, a defect rescued by the sune42 mutation, highlighting the role of Golgi‑mediated Ca2+ homeostasis in root hair growth.
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.
The study introduced full-length SOC1 genes from maize and soybean, and a partial SOC1 gene from blueberry, into tomato plants under constitutive promoters. While VcSOC1K and ZmSOC1 accelerated flowering, all three transgenes increased fruit number per plant mainly by promoting branching, and transcriptomic profiling revealed alterations in flowering, growth, and stress‑response pathways.
The study used transcriptomic and lipidomic profiling to investigate how chia (Salvia hispanica) leaves respond to short‑term (3 h) and prolonged (27 h) heat stress at 38 °C, revealing rapid activation of calcium‑signaling and heat‑shock pathways and reversible changes in triacylglycerol levels. Nearly all heat‑responsive genes returned to baseline expression after 24 h recovery, highlighting robust thermotolerance mechanisms that could inform improvement of other oilseed crops.
The study demonstrates that constitutively active MLO (faNTA) can rescue the fer-4 root‑hair bursting and polarity defects, restoring tip‑focused cytosolic Ca2+ oscillations and ROS accumulation, highlighting a FERONIA‑MLO signaling module that governs Ca2+ influx and ROS production during root‑hair tip growth. Genetic analysis of mlo15-4 further confirms MLO15 as a key regulator of these Ca2+ and ROS dynamics. The findings suggest MLO proteins act downstream of FER to coordinate calcium and ROS signals essential for root‑hair integrity.
Using an Arabidopsis line expressing the CBL1‑mRuby2‑GCaMP6s calcium reporter, the study uncovered distinct calcium signatures in intact root tissues when exposed to high (5 mM) and low (0.25 mM) nitrate concentrations. Root hairs displayed prominent calcium waves and spikes, while non‑hair epidermal cells showed asynchronous or absent responses, indicating cell‑type‑specific and nitrate‑concentration‑dependent calcium signaling.
The study shows that the mechanosensitive ion channel PIEZO in Arabidopsis thaliana regulates root elongation in response to magnetic fields and blue light, with mutant plants displaying significantly shorter roots under these conditions. PIEZO expression is up‑regulated by a leaf‑derived blue‑light signal in the presence of a magnetic field, influencing calcium efflux and auxin transport via interactions with PIN3, PIN6 and PIN7, and requiring the blue‑light receptors CRY1 and CRY2. Transcriptome analysis reveals that PIEZO integrates multiple hormonal and microRNA pathways, including miR5648‑5p‑mediated negative regulation, to coordinate these environmental responses.