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Molecular Plant

Elsevier BV

Preprints posted in the last 30 days, ranked by how well they match Molecular Plant's content profile, based on 39 papers previously published here. The average preprint has a 0.04% match score for this journal, so anything above that is already an above-average fit.

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LBD-type transcription factors suppress local and systemic nitrogen responses through distinct regulatory pathways

Kiba, T.; Takahashi, H.; Monden, K.; Sada, Y.; Koshihara, K.; Sato, M.; Bellegarde, F.; Hachiya, T.; Hirai, M. Y.; Yanagisawa, S.; Sakakibara, H.

2026-08-19 plant biology 10.64898/2026.08.14.744662 medRxiv
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Nitrogen (N) is a major determinant of plant growth and productivity. Because soil N availability and internal N demand fluctuate, plants have evolved sophisticated mechanisms to coordinate N acquisition and utilization at the whole-plant level. However, how this coordination is achieved remains poorly understood. Here, we show that N-inducible LATERAL ORGAN BOUNDARIES DOMAIN transcription factors LBD37, LBD38, and LBD39 (LBDs) function as repressors of local N uptake and assimilation and systemic N-demand signaling in Arabidopsis. Triple mutants lacking these three LBDs displayed enhanced nitrate influx and increased accumulation of nitrate, amino acids, and total N. Transcriptome analysis identified an array of N-starvation- and nitrate-inducible genes derepressed in shoots and roots, including C-TERMINALLY ENCODED PEPTIDE (CEP) and CEP DOWNSTREAM (CEPD) genes, as well as genes involved in N uptake and assimilation. Grafting and genetic analyses revealed that LBDs gate the systemic N-demand signaling relay by repressing CEP and CEPD expression organ-autonomously. We also found that LBDs locally repress genes involved in N uptake and assimilation through a distinct regulatory mechanism. We propose that LBDs are key transcriptional repressors in a regulatory framework for optimizing N acquisition and utilization under fluctuating N conditions at the whole-plant level.

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Port of Protein-Protein Interactomes: An experiment-based protein-protein interactome database for rice

Liu, X.; Lu, J.; Jia, L.; Xia, D.; Huang, J.; Cheng, Y.; Li, M.; Chen, Y.; Liu, X.; Li, G.; Liu, W.; Li, J.; Ying, J.; Wang, Y.; Li, Z.; Tong, X.; Hou, Y.; Zhiguo, E.; Zhang, J.; Zhang, J.

2026-08-20 systems biology 10.64898/2026.08.16.744343 medRxiv
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Protein-protein interactions (PPIs) play a crucial role in enabling proteins to carry out their functions within various biological processes (Hui et al., 2003). Since the introduction of the yeast two-hybrid (Y2H) method for PPI detection in 1989 (Fields and Song, 1989), the identification of PPIs has become a significant focus in modern biological research. PPI goes beyond examining individual proteins, allowing researchers to establish a comprehensive network that regulates biological processes. Rice, as a key model organism in plant biological studies, has been at the forefront of PPI research. In 2008, prominent rice scientists in China called for concerted efforts to define a comprehensive protein-protein interaction network experimentally, which aimed to facilitate the prediction of the functional mechanisms operating throughout a plants lifecycle (Zhang et al., 2008). With efforts for 2 decades, the experimentally identified rice PPIs have reached over ten thousand. Several public databases have been established to systematically collate and store PPIs, including STRING (Szklarczyk et al., 2019), BioGRID (Oughtred et al., 2020), IntAct (del Toro et al., 2022), PRIN (Gu et al., 2011), RicePPINet (Liu et al., 2017) and RiceNet v2 (Lee et al., 2015). However, most PPI datasets in rice stem from computational predictions, while experiment-based rice PPI datasets are fragmented due to the lack of systematic profiling at the rice PPIome level, which largely hinders information sharing in the rice research community. To bridge this gap, we constructed the Port of Protein-Protein Interactomes (POPPIN; https://riceome.hzau.edu.cn/poppin/), an integrated database dedicated to sharing experimentally verified PPIs and functional clues in rice. Empowered by high-throughput PPIome profiling technologies and text mining assisted by a large language model (Huang et al., 2025; Liu et al., 2025), POPPIN currently has deposited over 150,451 pieces of rice PPI-related information. Additionally, POPPIN provides detailed protein information, including GO annotations, subcellular localizations, domains, trait ontology (TO) information, and hyperlinks to external biological databases. Through offering a user-friendly web interface for search and dynamic network visualization, POPPIN serves as the first large-scale, experiment-based database for searchable PPIs in rice, and has the potential to be extended to other species under this structural framework.

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Rice brown spot resistance gene bsr1 also confers resistance to bacterial blight by suppressing sucrose efflux

Mizobuchi, R.; Hishida, A.; Juichi, H.; Michishita, R.; Tanaka, F.; Wakabayashi, Y.; Inoue, H.; Kuya, N.; Suzuki, N.; Endo, M.; Mikami, M.; Ohashi, S.; Matsumoto, K.; Ota, Y.; Yamakawa, T.; Nakamura, D.; Tsuiki, C.; Sato, H.

2026-08-07 plant biology 10.64898/2026.08.07.743414 medRxiv
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Brown spot (BS), caused by the fungal pathogen Bipolaris oryzae, is a major disease threatening global rice production. However, the genetic basis of host BS resistance remains unclear. Here, we identified brown spot resistance 1 (bsr1), a quantitative trait locus conferring BS resistance, by map-based cloning. We show that bsr1 encodes a sucrose transporter and that a near-isogenic line carrying bsr1 (bsr1-NIL) in the susceptible Koshihikari genetic background exhibited resistance to BS by suppressing sucrose efflux into the apoplast after pathogen attack. Furthermore, bsr1-NIL also showed strain-specific resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae through the same mechanism. These findings demonstrate that bsr1 confers dual resistance to fungal and bacterial diseases by regulating sucrose efflux. Our study identifies a previously unrecognized mechanism underlying resistance to both BS and bacterial blight and highlights bsr1 as a promising target for breeding disease-resistance rice cultivars. Rice (Oryza sativa L.) is a staple food for more than half of the worlds population1. Brown spot (BS), caused by the fungus Bipolaris oryzae, is one of the most prevalent fungal diseases of rice, and its incidence has increased under global warming2. BS infects coleoptiles, leaves, leaf sheaths, panicle branches, glumes, and spikelets, and severe infection can substantially reduce grain yield.

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Cross-Species Comparison of Topologically Associating Domains (TADs) in Cereals Reveals Their Role in Genome Stability During Evolution

Li, E.; Huang, L.; Shi, J.; Xu, G.; Liu, H.; Jin, W.; Wang, Y.; Tang, S.; Diao, X.; Song, W.; Xin, B.; Lai, J.; Chen, J.

2026-08-19 plant biology 10.64898/2026.08.13.744466 medRxiv
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Topologically associating domains (TADs) are essential structural and functional modules of the genome that play a crucial role in regulating gene expression. In this study, we systematically investigated the conservation and evolution of TADs in five closely related crops, including maize, sorghum, coix, foxtail millet and broomcorn millet. Our results show that 74% of TAD boundaries are conserved between two inbred maize lines, B73 and Mo17, and that approximately 50% or more of TAD boundaries are conserved across different crop species. TAD number remains relatively stable in the face of changes in genome size. However, the length of TADs varies depending on genome size. Furthermore, we found that large-scale transposable element expansion leads to TAD expansion, while chromosomal inversions lead to TAD fusion and the formation of new TAD boundaries. Frequent chromatin interactions between subgenome chromosomes occur after whole-genome duplication. Moreover, we also found that crossovers are enriched at TAD boundaries in maize, indicating the importance of TADs as a fundamental unit during species evolution. Overall, our study provides insights into the conservation and evolution of TADs in crop genomes and their roles in genome organization and function.

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Symbiont effectors modulate plant signalling to increase host stress resilience

Rehneke, L.; Osborne, R.; Lehmann, S.; Zhang, Y.; Roberts, J.; Altmann, S.; Köpff, E.; Eichmann, R.; Falter-Braun, P.; Shan, W.; Schäfer, P.

2026-08-19 plant biology 10.64898/2026.08.17.744369 medRxiv
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Plant colonizing mutualistic symbionts confer beneficial effects to their hosts, which often includes increased growth, and biotic and abiotic stress resilience. How these benefits are activated on a molecular level is mostly unknown. Here, we describe effector candidates of the fungal symbiont Serendipita indica (Si), which modulate plant stress signalling pathways. By analyzing the Si effector interactome, we reveal frequent targeting of stress related host proteins, which are linked to the identified effector signalling functions. Moreover, functional data indicate that Si effectors modulate abiotic stress response of Arabidopsis, as well as resistance to pathogen infection. Analysis of symbiont effectors might not only uncover previously unreported molecular mechanisms that increase plant fitness but might also be used to identify potential genetic traits for crop improvement under changing climates.

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Potato Agent: AI-Driven Data and Knowledge Exploration on an Agent-Ready Potato Multi-Omics Platform

Dong, Y.; Li, J.; Li, F.; Luo, J.; Jia, Y.; Li, D.; Wang, L.; Su, X.; Hu, J.; Shang, Y.; Huang, S.; Zhu, Y.; Jia, Y.

2026-08-13 plant biology 10.64898/2026.08.12.744101 medRxiv
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Potato is an important non-cereal food crop worldwide. However, the limited number of functionally validated genes remains a major bottleneck to favorable allele stacking and genome design breeding in potato. Rapid advances in AI agents offer a promising means to support crop breeding by translating natural-language questions into coordinated data analysis and knowledge retrieval. Their reliable use for potato breeding, however, is constrained by fragmented multi-omics resources that lack consistent curation and machine-accessible interfaces. Here, we constructed an agent-ready potato multi-omics database integrating genomic resources from 150 potato accessions, 259 bulk RNA-seq samples, and 14 spatial transcriptomic datasets into a pangenome, a tissue expression atlas, co-expression networks, and spatial expression maps accessible through open APIs. We developed 39 potato-specific Agent Skills for reproducible bioinformatics analysis and comprehensive data and knowledge exploration, enabling natural-language questions to be translated into standardized data-retrieval and analysis tasks. By integrating direct evidence from potato studies, functions of homologous genes in Arabidopsis, rice, and maize, and tissue expression patterns, we generated genome-wide functional predictions for 37,658 genes in the DM reference genome. We further developed Potato Agent as a multi-user, browser-based platform with isolated workspaces and online result preview, reducing the technical burden of agent deployment and providing direct access to integrated data, knowledge, and workflows. Case studies demonstrated its capabilities in reproducible bioinformatics analysis, agent-assisted identification of a tuber development regulator, scientific data visualization, and haplotype-aware promoter analysis and sgRNA design. Together, the agent-ready database and Potato Agent provide an integrated infrastructure for functional gene discovery and hybrid breeding in potato.

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From Plants to Patients: Mitochondrial Stress Signaling as a Systems Framework for Human Disease Vulnerability

Gokdemir, F. S.; Eyidogan, F.; Kubat, G. B.; Singh, K. K.

2026-08-21 bioinformatics 10.64898/2026.08.17.745221 medRxiv
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Mitochondria integrate bioenergetic metabolism, redox control, genome maintenance, and stress signaling across all eukaryotes. Although plant and human mitochondria diverged substantially during evolution, both systems retain systems-level principles for sensing mitochondrial dysfunction and communicating stress signals to the nucleus. Here, we develop an integrative comparative in silico framework to evaluate whether plant mitochondrial stress signaling can provide a useful conceptual model for interpreting human mitochondrial disease vulnerability. Core Arabidopsis thaliana regulators representing alternative respiration, mitochondrial retrograde signaling, translational stress control, and genome surveillance were compared with functionally analogous human regulators involved in integrated stress response (ISR) signaling, mitochondrial DNA maintenance, and mitochondrial disease phenotypes. Domain architecture, protein-protein interaction topology, enrichment profiles, disease-gene associations, and promoter motif architecture were integrated to assess cross-kingdom convergence at the level of stress-response organization rather than direct orthologs. The plant network formed a compact AOX-NAC-centered stress module associated with respiratory flexibility and retrograde signaling, whereas the human network displayed expanded ISR and mtDNA maintenance modules enriched for mitochondrial disease associations. Promoter motif analyses further indicated lineage-specific transcription factor signatures but broadly comparable stress-responsive regulatory logic. Collectively, these results support the concept that plant mitochondrial stress systems represent simplified resilience-oriented architectures that can help generate experimentally testable hypotheses about failure points in human mitochondrial stress responses.

8
HECT-type ligases facilitate autoubiquitination and degradation of other ubiquitin ligases to activate plant immunity

Wang, Z.; Mason, R. O.; Grey, H.; Spanos, C.; Orosa-Puente, B.; Spoel, S. H.

2026-08-07 plant biology 10.64898/2026.08.06.743213 medRxiv
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The ubiquitin-proteasome system (UPS) serves as the primary proteolytic machinery in eukaryotes, governing intracellular protein turnover to maintain proteome homeostasis. In plants, the HECT-type UPL3/4 ubiquitin ligases play vital roles in developmental and immune signaling. After ubiquitination by pathway-specific E3 ligases, substrates are physically relayed to proteasome-associated UPL3/4 ligases for further modification, which is necessary for their proteasome-mediated degradation. In this study, we investigated if the cellular influence of UPL3/4 extends beyond their direct role in substrate degradation. We discovered that UPL3/4 govern the ubiquitination not only of a broad array of immune-related substrates, but also of many UPS components, including E3 ligases. UPL3 physically interacts with PUB22, a pathway-specific U-box E3 ligase that negatively regulates immunity. PUB22 is controlled by a phospho-switch that converts it from an instable autoubiquitinated state to a stable phosphorylated E3 ligase that marks substrates for degradation. Remarkably, UPL3 only interacted with unphosphorylated PUB22 and facilitated its autoubiquitination-mediated degradation, thereby promoting the accumulation of PUB22 substrates. Moreover, the compromised immune phenotypes of upl3 upl4 mutant plants were largely dependent on PUB22 and its close paralogues. Thus, UPL3/4 control the stability of immune-related substrates not only through direct ubiquitination, but also indirectly by promoting autoubiquitination of PUB22 ligase and its paralogues. Controlling the stability of autoubiquitinating E3 ligases may be a universal mechanism whereby HECT-type ligases and the proteasomes they associated with, orchestrate cellular proteostasis in eukaryotes. Significance StatementThe ubiquitin-proteasome system (UPS) governs intracellular protein turnover to maintain proteome homeostasis in eukaryotes. Proteasome-associate HECT-type ubiquitin ligases play an important role in processing and degrading substrates delivered to the proteasome by pathway-specific E3 ligases. Here, we discover that in plants, HECT-type ligases not only promote the degradation of substrates, they also modify the E3 ligases that target these substrates to the proteasome. Specifically, HECT-type ligases facilitated or expanded the autoubiquitination of immune-suppressive E3 ligases, resulting in their proteasome-mediated degradation and onset of immunity. Our discoveries suggest that during plant immunity, HECT-type ligases and the proteasomes they associate with, control cellular proteostasis by governing the stabilities of both E3 ligases and their substrates.

9
The Lateral Protein Cluster as a Key Component of Plant Cell Polarity

Yoshinari, A.; Yunoki, K.; Ota, K.; Futami, K.; Motomura, K.; Mishiro-Sato, E.; Isoda, R.; Takeda, A.; Lindeboom, J. J.; Naramoto, S.; Nakamura, M.; Frommer, W. B.

2026-08-21 plant biology 10.64898/2026.08.17.745151 medRxiv
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Cell polarity is an ancient organizing principle across kingdoms. As in animal epithelial cells, plant cells asymmetrically distribute proteins to establish functionally distinct membrane domains. In roots, radial polarity distinguishes inner and outer cell surfaces and supports directional nutrient transport, yet its molecular basis remains poorly understood. Here, we show that the leucine-rich repeat receptor-like kinases CaMRLK and IRK occupy complementary lateral plasma membrane domains in Arabidopsis thaliana roots. Polarity-guided proximity labeling identified previously uncharacterized proteins associated with inner- and outer-lateral domains. Clade VII LRR-RLKs, protein S-acyltransferases, SICK, IRKI1, and a distinct group of NPH3/RPT2-LIKEs assemble into the Lateral Protein Cluster (LPC) through multivalent interactions. LPC components are conserved across land plants, and disruption of NRL function impairs morphogenesis in Arabidopsis and Marchantia polymorpha. Together, these findings establish the LPC as an evolutionarily conserved molecular machinery linking radial cell polarity to plant morphogenesis.

10
An Integrated Spatially Resolved Mechanistic Model of Hierarchical Auxin-Cytokinin-Ethylene Crosstalk Underlying Root Growth Inhibition in Arabidopsis

Fenech, M.; Fernandez-Moreno, J. P.; Daubermann, G. A.; Nawar, A.; Taylor, J. S.; Davis, H.; Belcapo, S.; Budnick, A.; Yaschenko, A. E.; Xu, C.; Hand, H.; Jackson, J.; Vollen, K.; Muller, K.; Kater, M. M.; Moura, D. S.; Ascencio-Ibanez, J. T.; Alonso, J. M.; Stepanova, A. N.

2026-08-19 plant biology 10.64898/2026.08.14.744203 medRxiv
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Decoding how plants integrate multiple hormone signals to coordinate growth requires tools capable of resolving pathway interactions at cellular resolution in living tissue. Here we present ACE (Auxin-Cytokinin-Ethylene) and ACE2, proof-of-concept single-locus reporters to simultaneously capture activity of multiple hormones. Deploying ACE alongside well-established reporters, exogenous hormone treatments, and reverse-genetic perturbations of hormone biosynthesis, signaling, and transport in three-day-old etiolated Arabidopsis seedlings, we dissect the spatiotemporal hierarchy governing primary root elongation and root apical meristem (RAM) size. We demonstrate that both ethylene- and cytokinin-triggered root growth inhibition involve a boost of TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1)-mediated auxin biosynthesis and AUXIN RESISTANT1 (AUX1)-dependent auxin redistribution. Two spatially distinct auxin responses underlie the respective root growth effects: ethylene expands TAA1-dependent auxin biosynthesis from the root vasculature into the epidermis and promotes AUX1-mediated auxin import into the transition and elongation zones to inhibit cell elongation, while cytokinin confines ethylene-dependent TAA1-boosted activity to the vasculature and drives auxin accumulation in lateral root cap cells to reduce RAM size. Together, these data establish a reciprocal regulatory loop between these hormones, positioning ethylene as a convergence node in auxin-cytokinin crosstalk, and cytokinin as a modulator of the ethylene-auxin interaction. Critically, the changes in cross-activated reporter patterns described for different genetic backgrounds, alongside quantitative assessment of hormone-specific inhibition of the mutants growth, were consistent with the multi-hormone network established over two decades of research, and added cell-type-resolved spatial detail and a proposed hierarchy for the etiolated seedling root. Finally, a second-generation reporter, ACE2, overcomes key technical limitations of ACE, expanding the platforms capacity toward a higher-order multi-hormone monitoring system. These resources expand the Arabidopsis genetic toolkit and provide a generalizable framework instrumental for dissecting multi-hormone signaling hierarchies at the cellular level.

11
Salt stress reverses root circumnutation, -skewing and -growth direction in Arabidopsis

Sheng, H.; Wijk, R. v.; Bouwmeester, H.; Munnik, T.

2026-08-28 plant biology 10.64898/2026.08.27.747533 medRxiv
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Plant roots exhibit remarkable developmental plasticity, resulting in the adaptation of growth direction and architecture upon environmental changes. Previously, we demonstrated that inorganic phosphate (Pi) triggers Arabidopsis roots to skew to the left when grown on tilted agar plates. This so-called 'phosphate-dependent skewing' (PDS) is caused by a right-handed (clockwise, CW) circumnutation of the root tip, which is driven by a left-handed (counterclockwise, CCW) cell file rotation (CFR) of epidermal cells in the root elongation zone, and involves the cortical microtubule cytoskeleton (Sheng et al., 2024). In the present study, we demonstrate that NaCl triggers a skewing response in the opposite direction and that all other helical movements are also reversed. Thus, 'Salt-Induced Rightward Skewing' (SIRS) is accompanied by a right-handed (CW) epidermal CFR, a left-handed (CCW) circumnutation of the root tip, and hence, a left-handed (CCW) helical root growth. Comparing different Na+- and Cl- salts revealed that SIRS is predominantly caused by cations, and can be induced by K+ and osmotic stress as well, although Na+ is most efficient. To get further insight into the mechanism underlying this response, we tested candidate genes from an earlier GWAS on root responses to salt stress (Deolu-Ajayi et al., 2019) for their potential involvement. This identified GLT1 and DOB1 as being involved in the root skewing response to Pi and NaCl, respectively. Our findings reveal that Pi and salinity elicit opposing effects on root circumnutation, and hence root skewing and growth direction. Understanding the molecular machinery driving this helical behaviour may help explain adaptive mechanisms, including changes in the spatial architecture of roots, and may facilitate the optimization of crop yield under abiotic stress conditions through breeding or crop management strategies. Our results also shed new light on halotropism, which is typically measured as a change in root growth direction to the right, which in the present study has been identified to represent SIRS.

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PlantAI: A Multi-Agent System for Plant Functional Genomics Analysis and Biological Knowledge Interpretation

Wu, T.; Yang, Z.; Shi, J.; Zou, M.; Wu, Y.; Jiang, S.; Xia, C.; Kong, L.; Yang, L.; Xia, Z.

2026-08-18 bioinformatics 10.64898/2026.08.14.744760 medRxiv
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Plant functional genomics requires the integration of sequence, expression, evolutionary, regulatory and literature evidence. However, the corresponding analyses are often distributed across disparate programs, scripts and databases, creating substantial barriers to task organization and result interpretation. Here, we present PlantAI, a multi-agent system that integrates bioinformatics analysis, project-level process tracking and knowledge-assisted interpretation. A Main Agent coordinates two complementary routes: an analysis route that invokes bioinformatics tools for RNA-seq and gene-family analyses, and a knowledge route that uses PlantAI-RAG for knowledge retrieval and evidence synthesis. PlantAI-RAG currently contains 31,207 plant-science literature records, comprising approximately 3.82 million normalized entities and 8.25 million literature-supported relation assertions. In an evaluation using plant-science questions, it achieved a Gold evidence-assertion recall of 86.7%, while strict accuracy ranged from 77% to 82% across three independent evaluator models. We further demonstrate an end-to-end task using 24 rice RNA-seq libraries collected under salt stress, spanning transcriptome analysis, candidate-family screening, HXK/HKL family analysis and knowledge-assisted interpretation, and prioritize OsHXK8 for experimental validation. By preserving analysis artifacts, run manifests, logs and environment records, PlantAI supports result verification and repeat execution while linking project-derived results to traceable literature evidence. Together, these capabilities provide an integrated and auditable framework to support plant functional genomics research.

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GLABRA2 regulates gene expression via its own EAR-motif mediated recruitment of the TPL/TPR corepressors

Ahmad, B.; Ulutas, A.; Bailey, A. K.; Marberg, L. R.; Schrick, K.

2026-08-27 plant biology 10.64898/2026.08.26.747311 medRxiv
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The Arabidopsis HD-Zip IV transcription factor GLABRA2 (GL2) displays dual regulatory capabilities, as an activator and repressor of genes that mediate cell-type differentiation of the epidermis. GL2 binds L1 box elements in the promoters of its target genes; however, the mechanisms by which it controls gene expression remain elusive. GL2 contains two putative ethylene-responsive element-binding factor-associated amphiphilic repression (EAR) motifs proximal to its N- and C-termini. The N-terminal EAR motif is highly conserved among GL2 orthologs that form a distinct clade of HD-Zip IV transcription factors in monocots and dicots. We demonstrate that deletion or Ala substitution of this N-terminal EAR motif results in a partial loss-of-function phenotypes in trichomes, non-hair root cells, and seed coat mucilage. In contrast, mutations affecting the C-terminal EAR motif display improper nuclear localization, likely due to protein misfolding. Yeast two-hybrid and in planta co-immunoprecipitation assays show that GL2 selectively interacts with the TOPLESS (TPL) and TPL-RELATED (TPR) corepressors via its N-terminal EAR motif. Fusion of the SUPERMAN REPRESSIVE DOMAIN X (SRDX) with the gl2 N-terminal EAR motif mutant (gl2EAR-N) rescues the epidermal defects of gl2 mutants. Transcriptome analysis of mutant and wild-type seedling roots further confirms the role of the GL2 N-terminal EAR motif in tuning gene expression. Our findings support a model whereby GL2 recruits TPL/TPR corepressors via its EAR motif to sequester histone-modifying proteins, resulting in chromatin remodeling required for epidermal development.

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Chromatin-Assisted Targeting Enables Precise DNA Methylation Editing in Plants

Jacobsen, S. E.; He, Y.; Wang, M.; Buckley, T. J.; Boone, B. A.; Li, E.; Shin, J. Y.; Alvarado, N.; Xu, B.; Nguyen, A.; Wang, S.; Zhou, Y.; Feng, S.

2026-08-26 plant biology 10.64898/2026.08.25.747117 medRxiv
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Precise installation of DNA methylation at selected loci offers a powerful strategy for regulating gene expression without altering DNA sequence, but existing plant epigenome editors are constrained by limited efficiency, locus dependence, and genome-wide off-target methylation. Here, we developed SunTag-MQ1v variants incorporating TRBIP1, which promotes removal of the antagonistic H3K4me3 mark, and CHLAMY, an oligomerizing alpha crystalline domain protein from Chlamydomonas reinhardtii. TRBIP1 enhanced methylation and silencing at the Arabidopsis FWA promoter but caused widespread off-target methylation and severe developmental defects. Adding CHLAMY produced SunTag-CHLAMY-TRBIP1-MQ1v (designated as SunTag-NOVA), which successfully overcame the lethality and widespread off-target effects associated with direct TRBIP1-MQ1v fusions. We demonstrate that CHLAMY drives higher-order oligomerization of the editing complex, which enhances target specificity and mitigates off-target accumulation. SunTag-NOVA robustly installed DNA methylation and repressed transcription at the endogenous FWA, FT and TMM genes with minimal genome-wide off-target consequences. These results show that combining local chromatin modification with controlled effector assembly can improve targeted DNA methylation, and establish SunTag-NOVA as a specific epigenome-editing platform for plants.

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The SWI/SNF subunit SWI3B functions with the m6A writer complex to establish embryo patterning in Arabidopsis

Gong, W.; Schwartz, U.; Fu, L.; Laengst, G.; Dresselhaus, T.

2026-08-13 plant biology 10.64898/2026.08.13.744595 medRxiv
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N6-methyladenosine (m6A) is the most abundant mRNA modification in eukaryotes and is essential for Arabidopsis embryogenesis. However, how m6A mRNA methylation is coordinated with other regulatory pathways during development including embryogenesis remains largely unknown. Here, we report the SWI/SNF chromatin-remodeling subunit SWI3B as a bona fide interactor of the m6A methyltransferase MTA. Like m6A writer mutants, SWI3B is required for early embryo development. We demonstrate that the interaction between MTA and SWI3B is required for MTA function during embryogenesis. MTA and SWI3B are both required to establish the correct expression pattern of WOX8 and proper auxin maxima during early embryogenesis. Transcriptome analysis of isolated embryos from mta, swi3b, and fip37 mutants identified a shared set of upregulated transcripts, including STM as well as several NAC and ERF transcription factors that are normally absent or expressed at very low levels during early embryogenesis. Embryo-specific overexpression of ANAC087 and ERF114 genes phenocopied early embryonic defects observed in mta and swi3b mutants, indicating that their ectopic expression contributes to the observed developmental phenotype. Moreover, SWI3B and MTA are both required for m6A deposition on specific developmental transcripts. Together, our findings uncover a mechanism by which chromatin remodeling and m6A-mediated RNA regulation cooperate to suppress the precocious stability of key developmental regulators, thereby contributing to the establishment of the transcriptional program required for early embryo patterning in Arabidopsis. HighlightsO_LIThe SWI/SNF subunit SWI3B is a functional interactor of the m6A methyltransferase MTA during Arabidopsis embryogenesis C_LIO_LISWI3B and MTA cooperate to establish embryo patterning, WOX8 expression, and auxin maxima C_LIO_LIMTA and SWI3B suppress precocious expression of STM, ANAC087 and ERF114 transcription factors that disrupt early embryo development C_LIO_LISWI3B links chromatin-associated regulation with m6A-mediated control of transcript stability C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=161 HEIGHT=200 SRC="FIGDIR/small/744595v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@cc0b07org.highwire.dtl.DTLVardef@1e7f8f9org.highwire.dtl.DTLVardef@8ace78org.highwire.dtl.DTLVardef@f939ff_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Pto evolved from malectin-like RLKs phosphorylates AvrPtoB to promote Prf-mediated immunity in Solanum pimpinellifolium

Liu, L.; Zhang, X.; Gong, Z.; Shi, J.; Chen, Q.; Wu, W.; Ye, J.; Wang, W.; Liu, J.; Xu, N.

2026-08-24 plant biology 10.64898/2026.08.23.746126 medRxiv
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Bacterial speck, caused by Pseudomonas syringae pv. tomato (Pst), is a devastating disease of tomato that severely limits global tomato productivity. Understanding the molecular mechanisms underlying Pst and tomato is essential for developing disease resistant varieties. Here, we demonstrate that Pto, the first disease-resistance gene conferring recognition of a specific pathogen, phosphorylates Pst type III effector AvrPtoB at serine 335 site. This post-translational modification triggers the dissociation of the Prf immune complex, enhancing immune signaling and reducing bacterial pathogenicity. Furthermore, evolutionary analyses indicate that Pto-associated proteins originated from malectin-like receptor kinases (MLRs) through loss of the extracellular domain. Crucially, we identified two key amino acid substitutions, Arg158 and Glu258 in Pto, which replace the ancestral lysine residues in MLRs (SpHREK1-1, SpHERK1-2 and SpHERK1-3). These substitutions stabilize Pto by preventing degradation mediated by AvrPtoB's E3 ubiquitin ligase activity. Our findings reveal a novel mechanism, by which Pto phosphorylates a bacterial effector to trigger enhanced immunity and elucidate the key evolutionary adaptations that have shaped Pto into a stable resistance protein.

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Conserved core and dynamic periphery NRC helper NLRs underpin immune receptor network evolution across Solanaceae

Hou, L.-Y.; Aung, M. H.; Oloc-oloc, I. B.; Kourelis, J.; WU, C.-H.

2026-08-11 plant biology 10.64898/2026.08.10.743904 medRxiv
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Plant nucleotide-binding leucine-rich repeat (NLR) proteins function as intracellular immune receptors that detect pathogen-derived signals and activate defense responses. The NRC (NLR required for cell death) receptor network plays central roles in immunity of solanaceous crops, yet its evolutionary diversification across Solanaceae remains poorly understood. Here, we combined comparative phylogenomics and comprehensive functional complementation assays to investigate the evolution and functional diversification of NRC helper NLRs across nine representative species from diverse genera within the Solanaceae. Phylogenetic analyses resolved 11 NRC helper subfamilies with distinct evolutionary trajectories, revealing a conserved core and dynamic periphery within the NLR receptor network. NRC2, NRC3, and NRC4 were broadly conserved across all examined species, whereas other NRC lineages exhibited degrees of presence-absence polymorphisms, lineage-specific expansion, and rapid diversification. Comparative genomic analyses revealed highly dynamic helper-sensor NLR cluster organization, indicating substantial genomic restructuring during Solanaceae evolution. Functional assays further showed that some NRC subfamilies retained broad compatibility with multiple sensor NLRs despite extensive sequence and genomic divergence, whereas other helpers displayed lineage-specific gains and losses of compatibility, revealing extensive rewiring of helper-sensor functional connections. Together, our study provides a cross-Solanaceae evolutionary and functional atlas of the NRC immune receptor network and demonstrates how a conserved core and dynamic periphery of NRC helper NLRs underpin the evolution of immune signaling specificity across Solanaceae.

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Whole-genome duplication drives biosynthetic gene cluster fragmentation and regulatory rewiring of monoterpene indole alkaloid metabolism in Strychnos

Liu, J.; Jong, J. J. Y.; Apuli, R.-P.; Zhuang, H.; Tham, R. J. K.; Lim, A. H.; Liu, W.; Ngiam, J. J.; Niissalo, M. A.; Khew, G. S.; Teh, B. T.; Salojarvi, J.

2026-08-22 evolutionary biology 10.64898/2026.08.19.745744 medRxiv
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Whole-genome duplications (WGDs) reshape plant genomes by generating redundancy, after which lineage-specific architectures emerge through fractionation, gene loss and rearrangement. How specialized metabolic pathways remain functionally integrated after such large-scale restructuring remains poorly understood. This problem is especially relevant for biosynthetic gene clusters (BGCs), which physically organize specialized-metabolism genes yet can be disrupted by post-duplication rearrangement. Here, we present the first chromosome-level genomes for Loganiaceae, including near telomere-to-telomere assemblies of Strychnos ignatii and S. pubescens, together with a draft genome of the extinct species S. ridleyi. Following a lineage-specific WGD, the two extant Strychnos species evolved contrasting genome-evolutionary trajectories and metabolite profiles: S. ignatii shows expansion of monoterpenoid- and monoterpene indole alkaloid (MIA)-associated gene families and strychnine-type MIA dominance, whereas S. pubescens exhibits elevated transposable element activity associated with DNA-binding with one finger (DOF)-linked regulatory rewiring and broader sesquiterpenoid- and triterpenoid-rich chemistry. Crucially, both species retain active strychnine biosynthesis despite fragmentation of a deeply conserved alkaloid BGC in MIA-producing Gentianales, revealing how pathway function can persist after disruption of ancestral BGC architecture. Comparative metabolomic and transcriptomic pathway analyses indicate norfluorocurarine oxidase (NO) as a major divergence point associated with strychnine accumulation. Promoter analyses, yeast one-hybrid assays, and electrophoretic mobility shift assays support a model in which S. ignatii retains the canonical jasmonate-responsive MYB, MYC2/bHLH, and AP2/ERF cis-regulatory module at NO, whereas the orthologous S. pubescens promoter shows reduced capacity to recruit these activators and instead exhibits a DOF-associated architecture. Together, our results show that WGD can decouple physical cluster architecture from pathway function, allowing specialized metabolic pathways to remain active while divergent chemical phenotypes evolve through lineage-specific combinations of coding-space expansion and transposable-element-associated cis-regulatory rewiring.

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ABC1K7: A 350-Myr chloroplast rheostat fine-tuned during coconut domestication

You, N.; Chen, Y.; John, M.; Zhou, N.; Li, W.; Cao, H.; Sun, C.

2026-08-09 genomics 10.64898/2026.08.04.742752 medRxiv
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Perennial crops follow different domestication trajectories from annuals, yet the molecular basis of slow-variable domestication--subtle tuning of conserved regulatory hubs--remains poorly characterized. We reconstructed the evolutionary history of the chloroplast kinase ABC1K7 across 9 seed plant species spanning [~]350 Myr, employing PAML codon models, IQ-TREE robust codon models, and protein-level phylogenetic inference, with AlphaFold2 structural modeling. ABC1K7 was under extreme purifying selection ({omega} = 0.073-0.104) across all seed plants. In coconut, a single Y[->]F substitution at residue 652--located >30 [A] from the catalytic core in a predicted intrinsically disordered region--represents the only non-synonymous change differentiating coconut from 7 of 8 angiosperm orthologs, and exhibits perfect co-segregation with domestication traits across a 17-year breeding panel (n = 327). These findings provide population-level evidence consistent with the slow-variable domestication model, identifying ABC1K orthologs as targets for perennial crop improvement.

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Two evolutionary histories in one nucleus: genome remodeling and allelic regulation underlying heterosis in hybrid oil palm

Su, X.; Peng, Y.; Yang, X.; Zhang, F.; Xu, Q.; Ma, Z.; Dong, Y.; Zhou, L.; Xue, H.; Cao, X.; Zou, Z.; Wang, Y.; Zhou, Y.; Zeng, X.

2026-08-31 genomics 10.64898/2026.08.27.747553 medRxiv
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Oil palm (Elaeis) is the primary source of global vegetable oil. Interspecific hybrids of Elaeis exhibit pronounced heterosis by integrating two distinct subgenomes into a single nucleus, effectively combining the high yield of African oil palm (E. guineensis) with the high unsaturated fatty acid content and disease resistance of American oil palm (E. oleifera). However, the genetic basis underlying heterosis is still unclear. Here, we combine phased genome assembly, comparative genomics, evolutionary genomics and haplotype-aware transcriptomics to unravel the genetic architecture of heterosis of hybrid oil palm. We assemble the highly heterozygous F1 genome ('Reyou 40', 3.75% heterozygosity) into a complete 1.73 Gb T2T haplotype (HapG) and a 1.84 Gb near-T2T haplotype (HapO with17 gaps). Despite 91.56% sequence identity, HapG and HapO diverged in LTR-RT occurrence and PAV affected genes, showing complementary biases in lipid metabolism and stress responses, respectively. Evolutionary genomics revealed that ancient WGDs preserved the palm family. Whereas lineage-specific lipid-related gene expansions in oil palm. Six ancient introgressed regions (~64 Mb) in HapG were reshaped by transposable elements and tandem duplication, showing an enrichment of genes related to resistance and lipid metabolism. Transcriptomically, 82.2% of allelic gene pairs maintained balanced expression, accompanied by parental functional complementarity and dosage buffering, revealing a potential regulatory basis for coordinating parental genetic differences in the hybrid genome. These haplotype-resolved genomic resources offer vital targets for understanding heterosis and accelerating oil palm molecular breeding.