BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Duckweeds – an example for evolution in flux DTSTART;VALUE=DATE-TIME:20260929T123000Z DTEND;VALUE=DATE-TIME:20260929T124500Z DTSTAMP;VALUE=DATE-TIME:20260916T143615Z UID:indico-contribution-430-2909@cern.ch DESCRIPTION:Speakers: Ingo Schubert (Leibniz Institute of Plant Genetics and Crop Plant Research (IPK)\, Gatersleben)\nThe shortest definition of e volution is maintenance and expansion of information by the change of info rmation (mutation) and subsequent selection (by environment). On the bioti c (post-cellular) level\, evolution led to +/- sexually isolated populatio ns of individuals\, called species. While karyotypic mutations can initiat e speciation\, genic mutations lead to allele diversity and adaptability. The main reasons for karyotype mutations (and thus for speciation) are mis -repaired DNA double-strand breaks. Another important route of speciation is reticulate evolution by fusion of (reduced or unreduced) gam etes from different species.\nOur actual collaborative efforts to resolve the phylogeny of duckweed genera demonstrate how these principles of evolu tion shaped duckweed diversity in the past and that they are still ongoing .\n\nhttps://indico.unina.it/event/117/contributions/2909/ LOCATION:Department of Agricultural Sciences of the University of Napoli F ederico II\, Portici\, Italy Sala Cinese URL:https://indico.unina.it/event/117/contributions/2909/ END:VEVENT BEGIN:VEVENT SUMMARY:The Impact of Polyploidy and Hybridization on Gene Expression in D uckweeds DTSTART;VALUE=DATE-TIME:20260929T131500Z DTEND;VALUE=DATE-TIME:20260929T133000Z DTSTAMP;VALUE=DATE-TIME:20260916T143615Z UID:indico-contribution-430-2906@cern.ch DESCRIPTION:Speakers: Ewout Crombez ()\nRecent discoveries of extensive pl oidy variation and natural hybridization have revealed an unexpected level of genomic diversity within duckweeds\, particularly in the genus *Lemna* . Naturally occurring cytotypes include auto-triploids\, auto-tetraploids\ , and diploid\, triploid\, tetraploid and aneuploid interspecific hybrids. This remarkable diversity provides a unique opportunity to investigate ho w genome duplication and hybridization shape transcriptional regulation. W e first focus on the highly variable *Lemna aequinoctialis x perpusilla* h ybrid species complex to examine how differences in ploidy level and subge nome composition influence the transcriptome. A selection of natural hybri d clones spanning multiple ploidy levels was exposed to salt stress for th ree weeks and subsequently profiled by RNA-sequencing\, enabling us to ass ess how ploidy affects transcriptional responses to environmental stress. In particular\, we examine patterns of expression level dominance\, homoeo log expression bias\, dosage and odd-even ploidy effects and regulatory di vergence across hybrids. Complementing the hybrid study\, we compare gene expression in diploid and colchicine-induced autotetraploid lineages of *S pirodela polyrhiza* under a long-term mild salt stress regime\, tracking t ranscriptional changes over many clonal generations. By comparing transcri ptional responses at the onset and after prolonged mild salt exposure\, we investigate how genome duplication influences the dynamics\, stability\, and plasticity of gene expression. Together\, these studies demonstrate th e potential of duckweeds as powerful model systems for investigating the m olecular consequences of genome duplication and hybridization\, and their roles in shaping plant responses to environmental stress.\n\nhttps://indic o.unina.it/event/117/contributions/2906/ LOCATION:Department of Agricultural Sciences of the University of Napoli F ederico II\, Portici\, Italy Sala Cinese URL:https://indico.unina.it/event/117/contributions/2906/ END:VEVENT BEGIN:VEVENT SUMMARY:Building a Spatial and Transcriptomic Framework for Transcription Factor Regulation in Wolffia australiana DTSTART;VALUE=DATE-TIME:20260929T130000Z DTEND;VALUE=DATE-TIME:20260929T131500Z DTSTAMP;VALUE=DATE-TIME:20260916T143615Z UID:indico-contribution-430-2905@cern.ch DESCRIPTION:Speakers: Kevin Cox (Washington University in St. Louis/Danfor th Center)\nUnderstanding how plants grow\, develop\, and respond to their environment requires not only identifying the genes involved\, but functi onally characterizing what each gene does. To understand how transcription factors regulate genes across tissues and organs\, transcriptional data n eeds to be placed within a spatial\, cellular\, and organismal context. *W olffia australiana* is an attractive system for addressing this fundamenta l question due to its small body plan\, fast clonal growth rates\, and com pact non-redundant genome. In our lab\, we use high-resolution\, 3D imagin g technologies and transcriptomics to pinpoint the localization of transcr iption factors and how they globally regulate genes in a whole plant. We u sed X-ray microscopy to capture the 3D architecture of *W. australiana*\, resolving the structure of the meristematic region and laying the groundwo rk for future cell segmentation and quantification. We further employed ex pansion microscopy\, which enables nanoscale imaging beyond the diffractio n limit\, achieving roughly 4x physical expansion of intact *W. australian a* and enhanced resolution of nuclei and chloroplasts. Together\, these im aging approaches provide a spatial and cellular scaffold for mapping trans criptional activity across the whole plant. To begin applying this framewo rk\, we examined the transcriptomic response to early salt stress by gener ating a bulk RNA-sequencing atlas over a 48-hour timecourse\, which identi fied specific transcription factors and functional pathways underlying the salt stress response. These imaging and transcriptomic approaches togethe r lay the groundwork for localizing transcription factor activity within a defined spatial and cellular context in *W. australiana*.\n\nhttps://indi co.unina.it/event/117/contributions/2905/ LOCATION:Department of Agricultural Sciences of the University of Napoli F ederico II\, Portici\, Italy Sala Cinese URL:https://indico.unina.it/event/117/contributions/2905/ END:VEVENT BEGIN:VEVENT SUMMARY:Transcriptomic and Epigenetic Insights into Flowering and Sexual R eproduction in L. aequinoctialis DTSTART;VALUE=DATE-TIME:20260929T124500Z DTEND;VALUE=DATE-TIME:20260929T130000Z DTSTAMP;VALUE=DATE-TIME:20260916T143615Z UID:indico-contribution-430-2903@cern.ch DESCRIPTION:Speakers: Cristian Mateo-Elizalde (Cold Spring Harbor Laborato ry)\nDuckweeds are aquatic monocotyledons including the smallest and faste st-growing angiosperms. They predominantly propagate clonally\, making sex ual reproduction and floral development poorly explored. The most fertile duckweed species belong to the section Alatae\, which includes Lemna aequi noctialis\, Lemna perpusilla and recently described interspecific hybrids including L. x aoukikusa (Stepanenko et al.\, 2025). To investigate the mo lecular basis of duckweed sexual reproduction\, we generated transcriptomi c profiles of reproductive tissues from the highly fertile hybrid accessio n L. aequinoctialis 8011. As a relatively recent hybridization event\, la8 011 constitutes an excellent model for studying flowering because of its h ighly synchronized floral development and the ability to evaluate the cont ribution of each subgenome.\n\nDuckweed evolution has been associated with gene loss linked to clonal propagation\, including components of the RNA- directed DNA methylation (RdDM) pathway (Ernst et al.\, 2025). This is ref lected in the absence of the canonical 24-nt small RNA peak (Ernst et al.\ , 2025\; Dombey et al.\, 2025). Our transcriptomic data reveal activation of genes involved in 24-nt small RNA biogenesis during flowering\, consist ent with preliminary small RNA-seq findings where these elements are resto red. Additionally\, we observed a slight increase in CHH methylation in an thers\, seeds\, embryos and endosperms\, supporting activation of the RdDM pathway. \n\nThese findings suggest that reproductive development is acco mpanied by finely tuned\, cell-specific epigenetic reprogramming that rese ts epigenetic marks accumulated during clonal propagation. Together\, our results provide new insight into the genomic\, and epigenetic dynamics und erlying natural hybridization and flowering\, establishing a molecular fra mework for future duckweed breeding.\n\nhttps://indico.unina.it/event/117/ contributions/2903/ LOCATION:Department of Agricultural Sciences of the University of Napoli F ederico II\, Portici\, Italy Sala Cinese URL:https://indico.unina.it/event/117/contributions/2903/ END:VEVENT END:VCALENDAR