CRK2 controls the spatiotemporal distribution of QSK1 at plasma membrane during osmotic stress
Authors: Jindal, S., Zeiner, A., Bondar, A., Neubergerova, M., Stolze, S. C., Harzen, A., Colina, F. J., Liekens, S., Pääkkönen, M., Merilahti, J., Kulich, I., Pleskot, R., Nakagami, H., Wrzaczek, M.
The study demonstrates that in Arabidopsis, the receptor-like kinase CRK2 phosphorylates and retains QSK1 at the plasma membrane under normal conditions, preventing excess callose deposition at plasmodesmata. Osmotic stress leads to dephosphorylation of QSK1, allowing its relocalization to plasmodesmata where it promotes stress‑induced callose accumulation, while CRK2 later moves to plasmodesmata to negatively regulate this deposition, revealing a dynamic gating mechanism.
CYSTEINE-RICH RLK2 regulates development via callose synthase-dependent symplastic transport in Arabidopsis
Authors: Zeiner, A., Krasensky-Wrzaczek, J., Jindal, S., Hajny, J., Sharma, M., Morina, F., Andresen, E., Pääkkönen, M., Küpper, H., Merilahti, J., Wrzaczek, M.
The study reveals that Arabidopsis CRK2 phosphorylates the callose synthases CALS1 and CALS3, influencing callose deposition at plasmodesmata and thereby affecting phloem loading and source‑to‑sink transport. Loss of CRK2 leads to starch accumulation in older leaves, a phenotype rescued by introducing functional CALS1 or CALS3 alleles, indicating that CRK2, CALS1, and CALS3 jointly regulate growth and development through control of intercellular transport.
The study examines how ectopic accumulation of methionine in Arabidopsis thaliana leaves, driven by a deregulated AtCGS transgene under a seed‑specific promoter, reshapes metabolism, gene expression, and DNA methylation. High‑methionine lines exhibit increased amino acids and sugars, activation of stress‑hormone pathways, and reduced expression of DNA methyltransferases, while low‑methionine lines show heightened non‑CG methylation without major transcriptional changes. Integrated transcriptomic and methylomic analyses reveal a feedback loop linking sulfur‑carbon metabolism, stress adaptation, and epigenetic regulation.
The study created transgenic Arabidopsis lines enabling inducible plasmodesmal closure via an overactive CALLOSE SYNTHASE3 allele (icals3m) and the C‑terminal domain of PDLP1, independent of pathogen signals. Induced closure triggered stress‑responsive gene expression, elevated salicylic acid levels, and enhanced resistance to Pseudomonas syringae, while also causing starch accumulation, reduced growth, and increased susceptibility to Botrytis cinerea, indicating that plasmodesmal closure itself can activate immune signaling.
Phylogenomic challenges in polyploid-rich lineages: Insights from paralog processing and reticulation methods using the complex genus Packera (Asteraceae: Senecioneae)
Authors: Moore-Pollard, E. R., Ellestad, P., Mandel, J.
The study examined how polyploidy, hybridization, and incomplete lineage sorting affect phylogenetic reconstructions in the genus Packera, evaluating several published paralog‑processing pipelines. Results showed that the choice of orthology and paralog handling methods markedly altered tree topology, time‑calibrated phylogenies, biogeographic histories, and detection of ancient reticulation, underscoring the need for careful methodological selection alongside comprehensive taxon sampling.
Integrative comparative transcriptomics using cultivated and wild rice reveals key regulators of developmental and photosynthetic progression along the rice leaf developmental gradient
Authors: Jathar, V., Vivek, A., Panda, M. K., Daware, A. V., Dwivedi, A., Rani, R., Kumar, S., Ranjan, A.
The study performed comparative gene expression profiling across four rice accessions—from shoot apical meristem to primordia stage P5—to delineate developmental and photosynthetic transitions in leaf development. By integrating differential expression and gene regulatory network analyses, the authors identified stage-specific regulatory events and key transcription factors, such as RDD1, ARID2, and ERF3, especially in the wild rice Oryza australiensis, offering a comprehensive framework for optimizing leaf function.
The study investigated chloroplast retrograde signals that regulate plasmodesmata-mediated intercellular trafficking, identifying heme from the tetrapyrrole biosynthetic pathway as a key modulator. Using Arabidopsis thaliana mutants and Nicotiana benthamiana gene silencing, the authors pinpointed heme‑responsive genes that likely alter plasmodesmata function, linking chloroplast signaling to coordinated plant development and resource allocation.
Arabidopsis lines with modified ascorbate concentrations reveal a link between ascorbate and auxin biosynthesis
Authors: Fenech, M., Zulian, V., Moya-Cuevas, J., Arnaud, D., Morilla, I., Smirnoff, N., Botella, M. A., Stepanova, A. N., Alonso, J. M., Martin-Pizarro, C., Amorim-Silva, V.
The study used Arabidopsis thaliana mutants with low (vtc2, vtc4) and high (vtc2/OE-VTC2) ascorbate levels to examine how ascorbate concentration affects gene expression and cellular homeostasis. Transcriptomic analysis revealed that altered ascorbate levels modulate defense and stress pathways, and that TAA1/TAR2‑mediated auxin biosynthesis is required for coping with elevated ascorbate in a light‑dependent manner.
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 shows that the SnRK1 catalytic subunit KIN10 directs tissue-specific growth‑defense programs in Arabidopsis thaliana by reshaping transcriptomes. kin10 knockout mutants exhibit altered root transcription, reduced root growth, and weakened defense against Pseudomonas syringae, whereas KIN10 overexpression activates shoot defense pathways, increasing ROS and salicylic acid signaling at the cost of growth.