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.
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 authors demonstrate that the WAVE/SCAR complex component BRK1 localizes to plasmodesmata and primary pit fields in Arabidopsis, using a BRK1‑YFP reporter line. BRK1 enrichment coincides with regions of reduced propidium iodide staining and colocalizes with aniline blue‑stained callose, suggesting that ARP2/3‑dependent actin branching contributes to plasmodesmata permeability regulation alongside formin‑mediated linear actin.
The study examined the evolution of plasmodesmata density across an evolutionary gradient of Flaveria species ranging from C3 to C4 photosynthetic types using electron microscopy. It identified two discrete, stepwise increases in plasmodesmata frequency, with a marked enrichment at the mesophyll‑bundle sheath interface in C4-like and C4 species, suggesting that heightened cell‑to‑cell connectivity underpins the development of C4 metabolism.
The study functionally characterizes three tomato CNR/FWL proteins (SlFWL2, SlFWL4, SlFWL5) and demonstrates that SlFWL5 localizes to plasmodesmata, where it regulates leaf size and morphology by promoting cell expansion likely through cell‑to‑cell communication. Gain‑ and loss‑of‑function transgenic tomato lines reveal that SlFWL5 is a key regulator of organ growth via modulation of plasmodesmatal signaling.
The study constructs a ~1‑million‑cell single‑nuclei transcriptome atlas of Arabidopsis leaves to reveal that drought stress accelerates transcriptional programs associated with maturation and aging, thereby limiting leaf growth in proportion to stress intensity. Targeted upregulation of FERRIC REDUCTION OXIDASE 6 in mesophyll cells partially rescues leaf growth under drought, demonstrating the functional relevance of these transcriptional changes.