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Plant Reproduction

Springer Science and Business Media LLC

Preprints posted in the last 90 days, ranked by how well they match Plant Reproduction's content profile, based on 13 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

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Assessing the relative contributions of different Arabidopsis thaliana stigma factors to pollen hydration.

Chadic, P. K.; Liu, R. K.; Goring, D. R.

2026-07-16 plant biology 10.64898/2026.07.15.738742 medRxiv
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Following pollination, Arabidopsis pollen grains rapidly hydrate through the transfer of water from the stigma to the pollen. Several stigma regulators of pollen hydration have been identified, and the corresponding mutants generally support milder defects in wildtype Col-0 pollen hydration, signifying the involvement of other unidentified factors in this process. Here, we uncovered a role for the stigma-specific mechanosensitive channel gene, MscS-Like 7 (MSL7), in supporting pollen hydration. While the msl7 mutant stigmas were found to support reduced hydration of wildtype Col-0 pollen, the phenotype was quite mild and very similar to that observed for other published pollen hydration mutants. Thus, we conducted a detailed comparison of different pollen hydration mutants on the stigma side (receptor kinases, PIP aquaporins) and pollen (PCP-Bs, MLS8) to compare pollen hydration mutant phenotypes and look for any additive effects of combining different mutants. Overall, all combinations resulted in the same mild hydration defect with no additional reductions in pollen hydration and no impact on pollen germination. This is in contrast to that observed for self-incompatible (SI) pollen from a transgenic Arabidopsis SI Col-0 line which shows very little pollen hydration and no pollen germination as part of the SI pollen rejection response. Together, these findings suggest that the regulation of compatible pollen hydration is quite complex and that there are likely other unknown mechanisms involved. Key MessageThe same mild pollen hydration defect is observed across very different Arabidopsis stigma mutants and it does not prevent pollen germination and pollen tube growth.

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Imaging Double Fertilization in Maize

Calhau, A.;Widiez, T.

2026-06-17 Plant Biology 10.64898/2026.06.12.731921 medRxiv
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Sexual reproduction in flowering plants relies on double fertilization, a process marked by two fusion events between the male and female gametes that lead to seed formation. Because this process unfolds within the embryo sac embedded deep inside the ovule, direct observation remains technically demanding, especially in maize, where the large size of female reproductive organs presents additional obstacles. The described method enables high-resolution visualization of cellular events unfolding during maize double fertilization. The approach integrates optimized fixation, clearing and confocal imaging of embryo sacs from ears pollinated with fluorescent pollen marker lines. Precise timing of embryo sac fixation is critical, allowing capture of key events such as pollen peri-germ cell membrane break-down or gamete karyogamy. The protocol provides detailed guidance for ovule dissection, fixation, preparation and renewal of the clearing solution and confocal imaging of embryo sacs. This method offers unprecedented access to the cellular events of double fertilization in maize, establishing a robust framework for studying reproductive processes and supporting future discoveries in plant reproduction.

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SWI3b restricts AGO5 expression to promote the initiation of megagametogenesis in Arabidopsis

Gong, W.; Liu, L.; Cai, H.; Dresselhaus, T.

2026-07-27 plant biology 10.64898/2026.07.26.740753 medRxiv
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Female germline development is fundamental to plant reproduction. During megasporogenesis, a somatic ovule cell differentiates into a megaspore mother cell (MMC) and undergoes meiosis to produce a single haploid megaspore while three spores degenerate. The surviving functional megaspore undergoes three rounds of mitosis during the process of megagametogenesis to produce the seven-celled female gametophyte or embryo sac. The mechanism by which the functional megaspore initiates gametogenesis remained unclear. Here, we show that the chromatin remodelling protein SWI3b is required for the initiation of megagametogenesis, but not for megasporogenesis. SWI3b activity either in the MMC or somatic ovule primordium cells alone is not sufficient for the initiation of megagametogenesis. We identified AGO5 as a direct target of SWI3b, which restricts AGO5 expression to the nucellus. We further show that SWI3b is required for maintaining low histone H3 lysine 9 acetylation level at the AGO5 locus, while elevated AGO5 abundance in the nucellus disrupts the initiation of megagametogenesis. In summary, our study reveals that SWI3b promotes the initiation of megagametogenesis through chromatin-mediated repression of AGO5, leading to its exclusion from the MMC and thereby linking histone acetylation and epigenetic mechanisms to the development of the female germ cells. HighlightsO_LIThe chromatin remodeling complex component SWI3b is required for the initiation of megagametogenesis and early embryo development. C_LIO_LIIn ovule primordia SWI3b restricts AGO5 expression to the nucellus C_LIO_LISWI3b acts via regulating histone acetylation around the AGO5 transcription start site. C_LIO_LIDevelopment of female germ cells are associated to histone acetylation C_LI

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The dandelion PARTHENOGENESIS gene dominantly modifies Arabidopsis fertilization and embryogenesis

Lima, R. B.; Wang, Y.; Cheng, Z.; Jansen, N.; Kheani, D.; Sackett, V.; Jacob, Y.; Underwood, C. J.

2026-08-26 plant biology 10.64898/2026.08.25.747015 medRxiv
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Parthenogenesis of totipotent egg cells is rare, yet widespread, across the tree of life but mechanistic insights into factors that control parthenogenesis remain sparse. The Taraxacum officinale PARTHENOGENESIS (ToPAR) gene encodes a C2H2-zinc finger and EAR domain containing protein which is required for parthenogenesis and clonal seed production in apomictic dandelions. Ectopic expression of ToPAR can trigger egg cell division in lettuce and maternal haploid induction in foxtail millet, and ToPAR has been employed in a high-penetrance synthetic apomixis system in hybrid rice. To date a convenient model system to study ToPAR function has yet to be established nor has the capacity for ToPAR to trigger cell division in non-gametic cells been tested. Here, we demonstrate that expression of ToPAR in egg cells of Arabidopsis thaliana using the EGG-CELL 1.1 promoter (pAtEC1.1) causes a reduction in seed set and can trigger egg cell division without fertilization. We found that the pAtEC1.1:ToPAR transgene is rarely transmitted through the female lineage where it causes aberrant cell divisions. Expression of ToPAR in sexual embryos under the WUSCHEL RELATED HOMEOBOX 8 (AtWOX8) promoter alters cell patterning disrupting morphogenesis. Our results demonstrate that A. thaliana can be a powerful system to dissect the mode of action of ToPAR, and that gamete-specific co-factors are not essential for its function.

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The RAP2.12 and RAP2.3 factors act downstream of LRR-MAL Receptor Kinases in Arabidopsis pollen-stigma interactions.

Bordeleau, S.; Lee, Y.; Samuel, M.; Goring, D.

2026-08-25 plant biology 10.64898/2026.08.24.746730 medRxiv
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Arabidopsis Leucine-Rich Repeat-Malectin Receptor Kinase (LRR-MAL RK) genes have been previously implicated in the early stages of pollen-pistil interactions to support compatible pollen. One member, Receptor Kinase in Flowers 1 (RKF1), has been associated with roles in the stigma to support pollen hydration as well as pollen tube growth. To better understand the function of RKF1 in these processes, a yeast two-hybrid screen was conducted with the RKF1 cytosolic kinase domain. Two positive interactors identified from this screen were the Group VII Ethylene Response Factors (ERFVIIs), RELATED TO APETALA 2.12 (RAP2.12) and RAP2.3. Their putative roles in pollen-pistil interactions were investigated using the quintuple erfvii mutant, and novel pistil-mediated pollen tube callose deposition phenotypes were uncovered during the pollen tube growth stage. Loss of seven LRR-MAL RKs including RKF1 in the pistil was previously found to cause an unusual phenotype where shorter callose plugs were deposited in wildtype pollen tubes compared to that seen in wildtype Col-0 pistils. Contrary to this, wildtype pollen tubes growing through the quintuple erfvii mutant pistil deposited callose plugs that were more elongated than that seen in wildtype Col-0 pistils. Further analyses with the proteolysis 6 (prt6) mutant and RAP2.12 rescue constructs were consistent with these phenotypes providing support that RKF1 is a negative regulator of RAP2.12 and RAP2.3 in the pistil during pollen tube growth.

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VigExp: A functionally verified platform for aiding cowpea (Vigna unguiculata) and related legume crop improvement

Su, H.; Mazurkiewicz, D.; Gursanscky, N.; Riboni, M.; Juranic, M.; Johnson, S. D.; Yow, J. H.; Deo, J.; Liu, Y.; Mattinson, A.; Leon-Martinez, G.; Escobar-Guzman, R.; Salinas-Gamboa, R.; Amasende-Morales, I.; Vielle-Calzada, J.-P.; Koltunow, A. M. G.; Ferguson, B. J.

2026-07-09 plant biology 10.64898/2026.06.30.735734 medRxiv
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Legumes include some of the worlds most significant crop species, such as cowpea (Vigna unguiculata), a subsistence crop widely grown in sub-Saharan Africa. Despite their importance, legume crop improvement is hindered by a lack of high-resolution expression data, particularly for reproductive tissues and cell types. Here, we report on VigExp, a tool for visualising cowpea gene expression datasets. We demonstrate its utility across a range of vegetative and reproductive cell types of varieties IT97K-499-35 and IT86D-1010, which exhibit 93.75% protein sequence conservation and are amenable to stable transformation. This includes previously published transcriptomes of vegetative, floral and seed tissues, combined with developmentally staged male and female reproductive tissues. Also integrated are novel transcriptomes of laser-captured cell types covering reproductive development from meiosis to early embryo formation post-fertilisation. Spatial expression patterns and transcript levels can be visualised through an electronic fluorescent pictograph (eFP) browser. Validated by RT-qPCR, in situ hybridisation, transgenic, and CRISPR gene editing analyses, the predictive accuracy of VigExp matches prior cowpea functional study observations. Critical genes for nodule development and regulation were also identified and their expression patterns established in cowpea. Novel reference genes, constitutively expressed gene promoters for visualization makers/gene-editing, and tissue and cell specific gene promoters for targeting these regions, are identified. The A-type cyclin, VuTAM2, was also identified, with a critical role in male meiosis established. Collectively, VigExp represents an adaptable and updatable resource to support crop improvement in cowpea and other legumes, which are often highly syntenic with respect to genome composition.

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FERONIA and ANJEA do not have a conserved role in self-incompatible Arabidopsis for self-pollen rejection.

Chadic, P.; Sidsworth, A.; Goring, D.

2026-08-10 plant biology 10.64898/2026.08.07.743519 medRxiv
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The rejection of self-incompatible (SI) Brassica pollen is mediated by three signaling branches that function in parallel in the stigma. The recognition of SI pollen by the stigma S-Receptor Kinase (SRK) results in activation of the ARM-Repeat-Containing 1 E3 ubiquitin ligase (ARC1) which mediates the degradation of compatibility factors, the FERONIA (FER) and ANJEA (ANJ) receptor kinases that induces ROS accumulation to inhibitory levels and the M Locus Protein Kinase (MLPK) which may also be connected to ROS production. Arabidopsis self-incompatibility is regulated by SRK as well, but the signaling events downstream of SRK following SI pollen perception are less well-understood. In this study, we evaluated the requirements of FER, ANJ and HERCULES RECEPTOR KINASE 1 (HERK1) for SI pollen rejection in the transgenic Arabidopsis thaliana SI-Col-0{psi} srka-1 line. The{psi} srka-1 T-DNA disrupting the expression of the endogenous{psi} SRKA gene was crossed into SI-Col-0 to prevent any potential SRK transgene silencing. T-DNA mutants for FER and ANJ/HERK1 were then crossed into the SI-Col-0{psi} srka-1 line. Using standard assays for pollen-stigma interactions, the SI phenotypes were assessed for the SI-Col-0 fer, SI-Col-0 anj-1 and SI-Col-0 anj-1 herk1-1 lines. Our results presented here indicated that FER and ANJ are not required in the stigma for Arabidopsis SI pollen rejection, further providing evidence for a divergence in the SI downstream signaling pathway in Arabidopsis.

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InMYB21B Promotes Petal Cell Expansion and Flower Opening in Japanese Morning Glory (Ipomoea nil)

Nakagawa, S.; Hoshino, A.

2026-08-24 plant biology 10.64898/2026.08.22.746480 medRxiv
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Flower opening is a complex developmental process involving coordinated changes in cell proliferation and cell expansion. Although several regulators of flower opening have been identified, how transcriptional programs are coordinated with the cellular and metabolic changes underlying petal expansion immediately before flower opening remains incompletely understood. Japanese morning glory (Ipomoea nil) is a suitable model for investigating these processes because its flowers open synchronously at a predictable time. This study aimed to identify transcriptional regulators involved in petal development and flower opening in Japanese morning glory. Temporal analyses of petal growth, sugar metabolism, and gene expression revealed that petal development was driven by both cell proliferation and cell expansion until approximately 48 h before flower opening, whereas cell expansion predominated thereafter. Weighted gene co-expression network analysis identified two genes encoding R2R3-MYB subgroup 19 transcription factors, InMYB21A and InMYB21B, as candidate regulators associated with petal development. CRISPR/Cas9-mediated knockout analysis revealed a prominent role for InMYB21B, whose loss markedly impaired petal cell expansion and prevented flower opening. InMYB21B knockout also impaired stamen and pistil development, resulting in male and female sterility. Starch degradation and glucose accumulation were impaired in InMYB21B knockout petals. Transcriptome analysis revealed delayed transcriptomic progression during petal development and reduced expression of genes associated with starch degradation, sucrose metabolism, cell wall remodeling, and water transport. These findings identify InMYB21B as a key regulator of petal cell expansion and flower opening in Japanese morning glory and show that loss of InMYB21B disrupts both metabolic and transcriptomic progression during late petal development.

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RNA-directed DNA methylation controls seed development and heat stress memory in barley

Abdu, A.; Szaker, H. M.; Kis, A.; Polgari, D.; Dalmadi, A.; Rakszegi, M.; Csorba, T.; Havelda, Z.

2026-07-30 plant biology 10.64898/2026.07.30.741739 medRxiv
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Plant specific RNA-directed DNA methylation (RdDM) mediates the DNA methylation of specific DNA sequences directed by 24-nucleotide long (nt) small interfering (si)RNAs. In crop plants we have limited information about the biological roles of the RdDM pathway including barley (Hordeum vulgare L). Here, we show that knockout of barley NRPD/E2A gene by genome editing, bringing about the drastic inhibition of RdDM pathway, results in the early arrest of developing caryopses rendering the mutant plants sterile. The knockout of the downstream component RDR2 gene, responsible for generating double stranded precursor RNAs for the production of 24-nt siRNAs, was associated with the loss of the majority of these siRNAs and also typically induced the early arrest of caryopsis development. However, the rdr2 mutants were able to produce a limited number of seeds exhibiting smaller size, endosperm filling anomalies and inhibited germination, which phenomenon was predominantly inherited maternally. Genome-wide analyses of gene expression revealed drastic up-and down-regulations in rdr2 mutants compared to the wild type. We did not find direct correlation between the changes of gene expression and the localization of 24-nt siRNA producing clusters indicating the indirect action of RdDM in these regulatory events. We also demonstrate that rdr2 mutant shows reduced heat stress memory capacity rendering the mutant plants more vulnerable to high temperature. Altogether, our data show the RdDM pathway is a major regulatory contributor to generative development and heat stress responses in barley.

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The BUD13 splicing regulator: transcript structure and expression in ovules of sexual and apomictic Paspalum notatum

Draga, S.; Siena, L. A.; Colono, C.; Gabelli, G.; Podio, M.; Vega, M. S.; Palumbo, F.; Ortiz, J. P. A.; Barcaccia, G.; Pessino, S. C.

2026-07-08 plant biology 10.64898/2026.06.17.732924 medRxiv
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Background and AimsPaspalum notatum reproduces through either sexuality or apomixis, two pathways that may coexist within the same individual and are regulated by interconnected molecular networks responsive to environmental cues. Here, we characterized the transcript structure and expression of BUD SITE SELECTION PROTEIN 13 (BUD13), a component of the RES spliceosomal complex previously reported as differentially expressed in florets of sexual and apomictic plants, as a first step toward testing its involvement in the molecular regulation of the apomixis-sexuality switch. MethodsPreviously generated floral and leaf transcriptomes from sexual and apomictic Paspalum notatum plants, including Oxford Nanopore long-read data, were mined to characterize BUD13 transcript structure and expression. Phylogenetic analyses and in silico mapping were conducted to infer evolutionary relationships and determine the origin of the transcripts. Differential expression was validated by RT-qPCR, while in situ hybridization was used to reveal cell-specific ovule expression patterns. Key resultsBUD13 is expressed in Paspalum notatum florets as a truncated isoform (SHORT) encoding a small protein lacking part of the herpes simplex virus regulatory protein (ICP4) domain. Two SHORT transcripts, SHORT1 and SHORT2, with different 5' untranslated region (UTR) regions, were identified in flowers. SHORT1 was consistently upregulated in apomictic ovules from premeiosis to anthesis. Both transcripts originated from a single genomic locus located in the subtelomeric region of the short arm of chromosome 6. SHORT isoforms with variable structures were detected in other monocots. In situ hybridization showed that, whereas BUD13 was expressed throughout sexual ovules, expression was absent from the female germline of apomictic ovules. A consistent expression was observed in somatic proembryos of aposporous embryo sacs. ConclusionsOur findings reveal structural, spatial and temporal divergence in BUD13 expression between sexual and apomictic reproductive programs, providing new insights into the molecular regulation of asexual seed formation.

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An integrative single-cell and spatial transcriptomics atlas highlights candidate regulatory factors in the development of gerbera capitulum

Gao, Y.; Li, F.; Jin, C.; de Ridder, D.; Immink, R.; Sun, Y.; Hu, P.; Cao, Y.; Shao, H.; van Dijk, A. D. J.; Wang, J.

2026-07-10 plant biology 10.64898/2026.07.05.736605 medRxiv
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In Asteraceae species, the capitulum is a compact inflorescence, featuring a characteristic reproductive structure. Despite the identification of a few key regulatory factors, the transcriptome-level information on the developing capitulum remains limited. Here, we applied single-cell and spatial transcriptome sequencing to investigate the developing Gerbera hybridas capitulum during floret differentiation. We obtained a transcriptomics atlas encompassing different stages of the Gerbera capitulum and analyzed the cellular and spatial dynamics of gene expression. Using marker gene expression and GO enrichment of cluster-specific DEGs, we annotated putative cell types and described changes in gene expression across sampled stages, potentially associated with ongoing developmental processes. We detected activity of previously undescribed MADS-box genes and defined their spatial expression patterns. Notably, the MADS-box gene GAGL12 was found to be enriched in the putative capitulum phloem cells. The GAGL12 protein was shown in yeast two-hybrid assays to interact with several other MADS-domain proteins with hypothesized functions in vasculature development, and further detailed in silico analyses supported a candidate role in the development of capitulum vasculature. Altogether, we provide integrative and dynamic transcriptomic insight into capitulum and floret development and lay a basis for future functional studies of the control and development of this intriguing reproductive structure.

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SEPALLATA MADS transcription factors act as key regulators in fertilization efficiency, ovule outer integument growth and mucilage secretory cell differentiation in Arabidopsis

Janeau, A.; Rambaud-Lavigne, L.; Babolin, N.; Paul, M.; Michaud, A.; Masson, L.; Lucas, J.; Scutt, C.; PARCY, F.; Colombo, L.; Zubieta, C.; Hugouvieux, V.

2026-08-24 plant biology 10.64898/2026.08.20.745741 medRxiv
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In angiosperms, ovule development requires the activity of the C, D and E classes of MADS genes, which encode key transcriptional regulators of reproductive development. The SEPALLATA (SEP) MADS transcription factors (MTFs), which belong to the E class, act as organizing hubs of MADS heterotetrameric complexes and play an essential role in the development of flower organs. However, the role of the SEP genes in ovule and seed development has been difficult to determine due to redundancy in the subclade, the lack of observable phenotypes in single and double sep1 sep2 mutants and the homeotic conversion of the carpel into sepal or leaf in higher order sep mutants. Here, we engineered a version of SEP3 (SEP3{Delta}M) that encodes a protein lacking the DNA-binding MADS-domain but retains the oligomerization domains needed for MADS protein heterotetramerization. In vitro experiments demonstrated the ability of SEP3{Delta}M to interact with the C and D classes of MTF, reducing the capability of such MADS complex to efficiently bind DNA. sep3{Delta}M plants showed a delay in flower opening and organ maturation and a reduced fertility. The ovules exhibited reduced outer integument growth, and the few seeds that developed showed impaired mucilage secretion upon imbibition. RNA-seq analysis of sep3{Delta}M demonstrated misregulation of genes involved in outer integument and seed coat development. Taken together, these data indicate the key role of SEP3-containing MADS complexes in proper ovule outer integument growth and seed coat development.

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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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SeedMeasure: an efficient approach and open-source program to quantify seed size

Sims, B.;Gaudinier, A.;Blackman, B.

2026-06-29 Plant Biology 10.64898/2026.06.27.734974 medRxiv
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PremiseSeed size and morphology are critical traits in agriculture, ecology, and genetics, but high-throughput quantification of these traits is often limited by labor-intensive manual measurements or expensive, platform-specific imaging software. Methods and ResultsWe developed SeedMeasure, a lightweight, open-source, and cross-platform command-line tool written in Python that automates the measurement of seed area, length, and width from images. Using a simple imaging setup, the program processes images by correcting for perspective skew, filtering debris, and exports quantitative data alongside quality-check images. We validated SeedMeasure across nine diverse species, ranging from small Arabidopsis thaliana seeds to large Zea mays kernels. The tool quickly handles images using multithreading and demonstrates high reproducibility, yielding low coefficients of variation across repeated runs. ConclusionsCompared to existing software, SeedMeasure is free, offers faster processing through parallel computing, and provides standalone executables that require no programming dependencies. SeedMeasure offers an accessible, cost-effective, and high-throughput approach for rapid phenotypic profiling, making advanced seed morphological analysis available to researchers without specialized laboratory hardware.

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From Diverse Prior Knowledge to Mechanistic Causal Network Using PSoup: A Case Study in Shoot Branching

Mitsanis, C.; Fortuna, N. Z.; Beveridge, C.

2026-08-10 plant biology 10.64898/2026.08.07.743620 medRxiv
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Mechanistic models of plant regulatory networks typically require extensive parameterization, limiting their generalisation and scalability. Here we present a parameter-free, topology-driven model of shoot branching that predicts phenotypic outcomes from network structure alone. We constructed a signed, directed causal network by distilling regulatory relationships from the published literature spanning many laboratories, species, years, data types, and methodological frameworks. This extracted the essential logic of the system, consistent with developmental-biological reasoning and anchored in empirical evidence. Using PSoup, which automatically translates network topology into algebraic equations, the model propagates information across the network and predicts the qualitative direction of change relative to a defined baseline, mirroring the comparative framework of biological experiments. The pipeline, from network construction through automated equation generation to prediction, is transparent and reproducible. Trained against branching phenotype data with 78 diverse perturbations spanning genetic mutations and hormone treatments, the model achieved 86% accuracy in predicting branching direction. On an independent test set of 84 perturbations measuring bud release and gene expression at nodes not used during training, accuracy reached 75%. The approach highlighted deficiencies in our understanding of the topology of the network around SMXL 6/7/8 and ABA nodes. Other errors came mainly from modelling choices, such as the threshold for scoring a node as changed relative to baseline. Beyond shoot branching, this work demonstrates a general strategy for synthesizing biological knowledge into validated predictive networks, providing a foundation for both applied breeding and the advancement of fundamental biology.

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A single-cell transcriptome atlas of the barley root apical meristem uncovers conserved and divergent roles of HvWOX5

Dolata, A.;Staut, J.;Demesa-Arevalo, E.;Lan, T.;Buchmann, G.;Solansky, P.;Berg, L.;Raissig, M.;Timmermans, M.;Korff, M.;Simon, R.;Vandepoele, K.;Stahl, Y.

2026-06-16 Plant Biology 10.64898/2026.06.15.732315 medRxiv
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Single-cell approaches have transformed plant developmental biology; however, cell-type-resolved resources for cereals remain limited. Here, we present a single-cell transcriptome atlas of the barley root apical meristem (RAM), which resolves 24 transcriptionally distinct cell populations. We assigned major root cell identities by integrating marker gene validation using Hybridization Chain Reaction (HCR) RNA fluorescence in situ hybridization and spatial transcriptomics with cross-species comparisons of published root atlases. Pseudotime analysis reconstructed developmental trajectories from the quiescent center to differentiating tissues, supporting the spatial and developmental organization of the atlas. We further demonstrated the utility of this resource by identifying HvWOX5 expression in the quiescent center and metaxylem and showing that HvWOX5 loss-of-function mutants displayed reduced root and meristem lengths, altered stem cell niche homeostasis, and disrupted metaxylem organization. Taken together, this atlas provides a framework for dissecting barley root development and identifies HvWOX5 as a key regulator of RAM organization and metaxylem patterning.

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AI-enabled simultaneous phenotyping of leaf vein and stomatal traits uncovers independent genetic control in maize

Sechi, M.; Porcedda, R.; Pallaoro, M.; Ferguson, J. N.; Dell'Acqua, M.; Vandin, A.; Caproni, L.

2026-08-04 plant biology 10.64898/2026.08.03.742415 medRxiv
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BackgroundLeaves maintain hydraulic homeostasis during photosynthesis through the coordinated action of stomata, which regulate gas exchange and transpiration, and veins, which supply water to the leaf lamina. While functional links between stomatal and vascular traits are known in dicots, their potential genetic coordination in C4 crops remains poorly understood. We investigated the genetic architecture of these traits in maize using a Multi-parent Advanced Generation Inter-Cross (MAGIC) population and a low-cost, high-throughput phenotyping platform integrating leaf clearing, digital microscopy, artificial intelligence, and image analysis ResultsWe phenotyped 285 recombinant inbred lines and the MAGIC founder lines, generating 8,072 images from 2,026 leaf samples taken from seedlings grown in controlled conditions. A YOLOv8-based model automatically detected stomata, while a custom and efficient image-processing pipeline quantified vein traits and stomatal spatial distribution patterns along cell bundles. This enabled simultaneous characterization of stomatal density, size, and distribution together with vein density, thickness, and bundle-associated spatial patterning. Substantial phenotypic variation was observed among genotypes, with strong correlations between abaxial and adaxial traits but no significant correlations between stomatal and vein traits. QTL mapping identified 37 genomic regions associated with stomatal and vein traits, including loci containing known developmental regulators such as stomatal density and distribution1 and stomagen1, as well as novel loci controlling stomatal spatial patterns, divergence between leaf surfaces and veins traits. ConclusionsThese results support independent genetic control of stomata and veins and decoupled contribution to water-use efficiency, providing a novel genetic framework to independently optimize leaf hydraulic capacity and gas exchange in target environments.

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Head-to-head organized segmental paralogs AtOFP2 and AtOFP17 exhibit differential, spatio-temporal partitioning of function, and negative regulation of multiple developmental traits including seed-yield and root architecture

Chahar, N.; Pokhriyal, E.; Yadav, S.; Ren, B.; Dangwal, M.; Das, S.

2026-07-09 plant biology 10.64898/2026.06.30.735610 medRxiv
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Ovate Family Proteins (OFPs) are a class of plant-specific, negative nuclear transcriptional regulators characterized by conserved C-terminal OVATE domain. This study on comparative functional characterization of two head-to-head arranged OFPs - AtOFP2 (Ovate-OFP with full ovate domain) and AtOFP17 (Ovate-Like OFP with partial ovate domain) provides critical insight into how structural variations in ovate domain leads to functional divergence. Detailed phenotypic analysis of 28 physical and physiological traits of loss- and gain-of-function mutants revealed that both genes act as broad, pleotropic repressors of plant growth and development. Removal of repression in knock-down mutants of both genes exhibited reduced duration of seed dormancy, faster rate of germination and growth, bigger plants and significantly higher seed yield. In contrast, constitutive over-expression showed a generalized repressive nature of both genes, with nuanced differences for fine tuning of specific traits. For example, both genes showed antagonistic behaviours on root hair architecture. AtOFP2 act as a strong repressor of root hair development whereas AtOFP17 is a stronger repressor of hypocotyl and root cell architecture. AtOFP17 owing to partial ovate domain exerts a mild level of repression throughout life span as indicated by smaller plants and lesser yield in knock-down AtOFP17 mutants. On the contrary, AtOFP2 exerted a much stronger repressor effect in which > 90% over-expression mutants died at the juvenile stage ; the survival of remaining 10% is probably owing to activation of dosage-dependent feedback loop mechanism as indicated by normal growth of mature plants, and is also evident by transcriptome data. Transcriptome analysis of roots of 7-day old seedling of knock-down and over-expression mutants of AtOFP2 showed downregulation of OFP2 in over-expressed mutants. However, severely stunted phenotype indicated presence of stable OFP2 protein to exert effects. Analysis of DEGs in OFP2 mutants revealed that it acts as an important regulator working at intersection of hormonal signalling affecting critical genes required for auxin, cytokinin, GA, BR and ABA functioning. Perturbations across hormonal signalling pathways affects cell wall remodelling factors such as EXPANSINS, Xyloglucan hydrolases (XTHs) and cellulose synthases (CSLs) causing overall stunted growth; and epidermal patterning genes such as WER, GL1, EGL3, TTG1 leading to severely reduced root length and root hairs. Significantly, functional analysis of this master regulator highlighted a significant economic potential. Knockdown of both these genes relieves their natural repression on reproductive traits, leading to longer siliques, bigger and heavier seeds, and substantially increased overall seed yield, positioning AtOFP2 and AtOFP17 as highly valuable targets for agricultural crop improvement.

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Differential Regulation of Branched-Chain Amino Acids During Early Germination of Mungbean (Vigna radiata L.)

Kim, C.; Kwon, H.; Lim, S. D.; Jo, Y.-J.; Ha, J.

2026-08-03 plant biology 10.64898/2026.07.31.741962 medRxiv
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Branched-chain amino acids (BCAAs) are essential amino acids involved in protein synthesis and energy metabolism. Because animals cannot synthesize BCAA de novo, plant-derived BCAAs are important to human nutrition. Although mungbean sprouts are widely consumed as functional plant-based food materials, changes in individual BCAA accumulation and their transcriptional regulation during mungbean germination remain poorly understood. In this study, amino acid contents and transcriptomic profiles were analyzed at three germination stages, 8H, 24H, and 72H. Total BCAA content increased during germination, whereas individual BCAAs exhibited distinct temporal accumulation patterns. Isoleucine and valine increased until 72H, while leucine increased during early germination and decreased after 24H. Transcriptome analysis revealed time-dependent expression changes in BCAA biosynthesis and degradation genes associated with the leucine decrease after 24H. These findings suggest that 24H represents an important transition point for BCAA accumulation and compositional change during mungbean germination. This study provides molecular evidence for the regulation of BCAA metabolism during mungbean germination and supports the potential use of germinated mungbean as a plant-based amino acid resource.

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Anthocyanin biosynthesis gene activation in nitrogen deprived Utricularia gibba L. under light or darkness

Meckoni, S. N.; de Oliveira, J. A. V. S.; Pucker, B.

2026-08-28 plant biology 10.64898/2026.08.27.747637 medRxiv
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Utricularia gibba L. is an aquatic carnivorous plant with a diverse set of capabilities. Reddening of traps frequently occurs in old in vitro cultures. While anthocyanins are often responsible for red coloration in plants, not every plant turns red. Stress factors like high light or excess sucrose have previously been shown to induce the formation of anthocyanins. Here, we hypothesized the red trap formation to be dependent on nutrient deprivation and tested nitrogen deprivation. The results suggest, that only in combination with light, nitrogen deficiency leads to the activation of the complete anthocyanin biosynthesis pathway and visible red coloration. However, in darkness, anthocyanin biosynthesis appears generally less active compared to light conditions and expression of most anthocyanin biosynthesis genes is not significantly upregulated under nitrogen deficiency.