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32nd International Conference on Arabidopsis ResearcH Abstract Book ASSOCIATION OF APPLIED BIOLOGISTS Abstracts are included herein without any liability for loss or damage suffered as a result of their application or use. Reference herein to trade names and proprietary products without special acknowledgement does not imply that such names, as defined by the relevant protection laws, may be regarded as unprotected and thus free for general use. No endorsement of named products is intended nor is any criticism implied of similar products which are not mentioned. This publication is copyright under the Berne Convention and the Universal Copyright Convention. Multiple copying of the contents of this publication without permission from both the Association of Applied Biologists, through the AAB Office, and separately from the author, or other holder of the unilateral copyright, is always illegal. These Abstracts have been prepared for use at the meeting only and should not be cited. ENQUIRIES Enquiries concerning the technical content of the Abstracts should be addressed directly to the authors; however, other matters should be directed to the Executive Officer, Dr Geraint Parry ([email protected]) at the AAB Office, Warwick Enterprise Park, Wellesbourne, Warwick CV35 9EF, UK ©2022 The Association of Applied Biologists ICAR2O22: Sponsors Lyrata Sponsors 1 ICAR2O22: Sponsors Lyrata Sponsors 2 ICAR2O22: Sponsors Arenosa Sponsors 3 ICAR2O22: Sponsors Session Sponsors Local Sponsors 4 Contents Page Meeting Schedule 1-15 Keynote Abstracts 17-20 Community Resources Session 21 Plenary Sessions Abstracts 22-60 Concurrent Sessions Abstracts 61-200 Workshop Sessions 201-209 Posters Abstracts 210-549 List of In-Person delegates 551-564 List of Online delegates 565-569 ICAR2O22 Meeting Information NOTE: All times are in BST (GMT+1). Meeting Website: https://web.cvent.com/event/93e87fea-a118-4c33-8ae9- 3aba4090f40a/summary If you have any urgent questions please contact: > Dr Geraint Parry, ICAR2022 Director > [email protected] > +44 (0) 7411 967 414 Meeting Venue: ICC Belfast, 2 Lanyon Pl, Belfast BT1 3WH, United Kingdom COVID Requirements Our absolute priority is to organise an in-person event that is safe for everyone who attends. There are currently no COVID restrictions in Northern Ireland however we must be aware that contracting COVID would be significant problem for visitors needing to return to their country of origin. There is now no distinction between vaccinated and non- vaccinated individuals when travelling to Northern Ireland. However we very much recommend that people are vaccinated before travelling Mask-wearing is optional in the UK but we will advise wearing masks in crowded areas and on public transport. We will advise mask-wearing during sessions when people are sitting close together for long periods. Given the number of attendess and capacity of the meeting venue social distancing should be possible. 1 ICAR2O22 Local Travel in Belfast The meeting venue is walkable from all Belfast City Centre hotels. Please enter the conference venue through the Riverfront Entrance. Car parking APCOA Lanyon Place Car Park, 6 Lanyon Pl, Belfast BT1 3FT Delegates can use the Lanyon Place Car Park - Pre-book with the promo code CON10 PRE-BOOK HERE. This is a £10 per day charge (normally £25). The car park is available 24/7 and there is a height restriction of 2.10 metres. Local Taxi numbers: Belfast Cabs: +44 (0) 7446 014761 Value Cabs: +44 (0) 28 9080 9080 Venues for other conference events City Hall Reception Venue: Donegal Square N, Belfast BT1 5GS The venue is a 10 minute straightline walk from the ICC Belfast. If needed please ask conference staff for directions. Canapes and drinks will be served at City Hall. Attendees will receive an extra drink token for this event. There will be NO cash-bar. Conference Dinner Venue: Titanic Museum, 1 Olympic Way, Queen’s Road, Belfast BT3 9EP This venue is a 25 minute walk along the river from the ICC Belfast. Please ask meeting staff if a taxi is required to move between venues. Uber is also available for use in Belfast. 2 ICAR2O22 Details of the ICC Belfast Conference Venue ICAR2022 events take place on four levels at the ICC. There are escalators, lifts and a staircase to move between levels. Ground floor Meeting registration and Conference information is in the Riverfront Foyer. The registration and information booth will be open from: June 20th: 1pm- 8pm June 21st: 8.30am- 6pm June 22nd: 8.30am- 2pm June 23rd: 8.30am- 2pm June 24th: 8.30am- 2pm Level 1: Plenary talks take place in Hall 1A The Poster and Exhibiton space is in Hall 1BCD Coffee breaks, Lunch and the opening reception will be held in Hall 1BCD Concurrent and Workshop Sessions will be held in Hall 1A, Hall 2A and Hall 2B. Level 2: The Speaker Preview is located in Boardroom 2. Level 3: A workshop session will be held in Meeting Room 1 3 ICAR2O22 Catering information Coffee breaks, lunch and the Opening Reception will be held in Hall 1BCD. All meeting catering will be vegetarian. Drinks tokens: Meeting attendees will receive drink tokens in their conference bag. These can be used at the Opening Reception, Poster sessions 1 and 2. These can be redeemed for beer, wine or a soft drinks. At the ICC, additional drinks can be purchased at local prices. Lunch timings: June 21st: 1.30pm-2.30pm June 22nd: 1pm-2pm June 23rd: 1pm-2pm June 24th: 12.30pm-1.30pm If you have requested specific dietary requirements then please ask event staff where these meals are located. Poster Information In-person delegates should bring a poster in portrait orientation with maximum size A0. Prior to the event and within this book presenters will be issued with a Poster number so that they can locate their poster space. Posters with Even-numbers should present on Tuesday June 21st for which Agrisera will provide a poster prize. Posters with Odd-numbers should present Wednesday June 22nd from which Plants-MDPI will provide a poster prize. 4 ICAR2O22 ICAR2022 Code of Conduct. The Multinational Arabidopsis Steering Committee (MASC) and the organisers of ICAR2022 are committed to ensuring that ICAR conferences are a welcoming and inclusive space for sharing of ideas, knowledge exchange and for developing collaborative opportunities for everyone who attends. To this end, ICAR2022 will provide a safe environment that promotes equal opportunity and treatment for all participants and that is free of harassment and discrimination. This code of conduct applies to all registered attendees, speakers, exhibitors, staff, contractors, volunteers, and guests; and it applies both within the ICAR2022 conference venue, within the online-platform and in associated events and locations where ICAR2022 conference delegates are present. Download full Code of Conduct from MASC website 5 ICAR2O22 ICAR2022 Weed Stampede ICAR meetings organised by the North American Arabidopsis Steering Committee (NAASC) have a long tradition of hosting a ‘Weed Stampede 5K’ as part of the event social calendar. We will continue this tradition at ICAR2022 with the ‘Run for the Throne: 5K Weed Stampede’ run/walk that takes place at 7.30am on Wednesday June 22nd leaving from outside the Riverside Foyer of the ICC Belfast. This (mostly) non-competitive 5K will be led by a Aoife McVeigh from VisitBelfast and takes in a course along the river Lagan. A member of conference staff will be walking the route over the an hour and will be ‘sweeping’ to ensure all participants safely finish the event. Participants take part at their own risk. In case of emergency call ‘999’ to access the UK Ambulance Service. A digital route map will be supplied to all participants. 6 ICAR2O22 ICAR2022 Meeting Schedule NOTE: All times are in BST (GMT+1). Monday June 20th 2022 1300: Registration and Venue Opens: Riverfront Foyer 1300: Coffee and Tea available Hall 1BCD 1600 Welcome to ICAR2022 Hall 1A Steven Spoel, University of Edinburgh Final GARNet Chair 1605 Keynote 1 Hall 1A Caroline Dean (John Innes Centre) 1650 Keynote 2 Hall 1A Liam Dolan (Gregor Mendel Institute) 1735 Community Resources Session Hall 1A 1830 Opening Reception Hall 1BCD A hot buffet will be served at this event in which delegates can use provided drink tokens 7 ICAR2O22 Tuesday June 21st 2022 0900: Plenary 1: Robustness in Genetic Networks Hall 1A 1100 Tea Break 1130 Plenary 2: Epigenetics and Chromatin Biology Hall 1A 1330 Lunch Hall 1BCD 1430 Concurrent Sessions 1-3 Phase separation in plants Hall 1A Plant Logic Hall 2A Internal and external regulation of development Hall 2B 1600 Tea Break 1630 Workshop Sessions 1-4 IN PLANTA: INclusive Practices Leveraging Arabidopsis as a Nexus for Training & Application Hall 1A Navigating the Nagoya protocol. Access and benefit sharing rights and digital sequence information: how they impact the Arabidopsis research Hall 2A 8 ICAR2O22 Novel tools in plant biology and bioengineering Hall 2B Plant Epigenetics and Chromatin Dynamics Meeting Room 1 1800- 2100 Poster Session 1 (Even numbered posters) Hall 1BCD A hot buffet will be served in Hall 1BCD Delegates can use provided drink tokens Poster Prize supplied by Agrisera Free Evening. Please take advantage of the Belfast nightlife 9 ICAR2O22 Wednesday June 22nd 2022 0900 Plenary 3: From Models to Crops Hall 1A 1100 Tea Break 1130 Concurrent Sessions 4-6 Arabidopsis as a model for adaptive evolution and global change genomics Hall 1A Arabidopsis small RNAs Hall 2A Interactions between nutrient and hormone signalling pathways Hall 2B 1300 Lunch Hall 1BCD 1400 Plenary 4: The Dynamic Proteome Hall 1A 1600 Tea Break 1630 Concurrent Sessions 7-9 Systems Biology of Plant-Pathogens Interactions Hall 1A Protoplast Biology or Single Cell Biology Hall 2A The Next Big Idea: NBI2022 Hall 2B 10 1 ICAR2O22 1800- 2100 Poster Session 2 (Odd numbered posters) Hall 1BCD A hot finger buffet will be served in Hall 1BCD. Delegates can use provided drink tokens Poster Prize supplied by MDPI-Plants 8:00pm Drinks Reception at Belfast City Hall (Tickets required) 11 ICAR2O22 Thursday June 23rd 2022 0900 Plenary 5: Principles of Morphogenesis Hall 1A 1100 Tea Break 1130 Concurrent Sessions 10-12 Beyond the transcriptome: Integrated omics networks in Arabidopsis Hall 1A Protein post-translational modifications and hormone signaling Hall 2A, Keeping cool in a warming world – the effect of cold on plant development Hall 2B 1300 Lunch Hall 1BCD 1400 Concurrent Sessions 13-15 A tale of dying cell: advances and prospects in plant programmed cell death research Hall 1A Plant Proteostasis: Mechanisms underpinning protein abundance in cells. Hall 2A Novel tools to explore plant cell wall dynamics Hall 2B 1530 Tea Break 12 ICAR2O22 1600 Workshop Sessions 5-8 Arabidopsis Informatics Hall 1A Application of long read sequencing to Arabidopsis genomics and genetics Hall 2A Standing on the shoulders of Arabidopsis: success stories of application Hall 2B Plant Orphan Genes Chaired Online. Broadcast in Meeting Room 1 1800 Entry to Titanic Museum Exhibition (Tickets required) 1900 Conference Dinner at Titanic Museum (Tickets required) 13 ICAR2O22 Friday June 24th 2022 0900: Concurrent Sessions 16-18 Expanding the universe of small proteins: uncovering the roles of smORFs, microProteins and SSPs in plant biology Hall 1A Advanced Plant Mineral Nutrition and Phytoremediation Hall 2A Cell surface signalling - receptor kinases and their ligands Hall 2B 1030 Tea Break 1100 Concurrent Sessions 19-21 Circadian Biology Hall 1A Translational Regulation of Gene Expression Hall 2A Watching biochemistry live - Genetically encoded fluorescent sensors in plants Hall 2B 1230 Lunch Hall 1BCD 1330 Plenary 6: Photobiology and Optogenetics. Hall 1A 14 5 ICAR2O22 1530 Keynote 3 Hall 1A Keiki Torii (University of Texas, Austin) 1615: Closing Ceremony and introduction of ICAR2023 Hall 1A Keynote sessions supported by RIKEN 15 ICAR2023 June 5 – 9,22023 ICAR CHIBA, JAPAN O22 Join us for the 33rd International Conference on Arabidopsis Research Arabidopsis for SDGs Scientific Sessions ・From single cells to an organism ・Interactions between organisms ・Integration of environmental cues ・Functional metabolomics ・Evolution and ecology ・Sustainable society and plants Confirmed Invited Speakers Keynote Speakers Joseph R. Ecker Dirk Inzé Kazuko Yamaguchi-Shinozaki Plenary Speakers Asaph Aharoni Cheng-Ruei Lee Gabriela Auge Sibongile Mafu Eunyoung Chae Yoshikatsu Matsubayashi José M. Estevez Edwige Moyroud Debora Gasperini Kalika Prasad Anja Geitmann Steven Runo Masami Yokota Hirai Bert De Rybel Kim Johnson Kee Hoon Sohn Filip Kolář Xiufang Xin 16 https://icar2023.org/ 17 ICAR2O22 Keynote 1: June 20th 1600-1645 Caroline Dean, John Innes Centre Extracting seasonal information from noisy temperature cues In-Person Keynote 2: June 20th 1645-1730 Liam Dolan, Gregor Mendel Institute, Austria Development and evolution of the land plant-soil interface In-Person Keynote 3: June 24th 1530-1615 Keiko Torii, The University of Texas at Austin, HHMI, USA; Nagoya University, Japan Breaking the Silence: How to make small plant mouths that support our sustenance In-Person 17 Extracting seasonal information from noisy temperature cues CAROLINE DEAN John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK ABSTRACT Plants use many aspects of the environment to regulate their growth and development. To monitor seasonal cues plants must integrate external signals over a long-time scale. For example, naturally fluctuating temperature signals are registered throughout winter in the process of vernalization, which aligns flowering with the favourable conditions of spring. In Arabidopsis, vernalization is associated with epigenetic silencing of the floral repressor FLC. Dissection of this mechanism has revealed that temperature sensing is distributed throughout the network regulating FLC. Multiple facets of the fluctuating temperature profile are integrated via different nodes in the pathway. These promote a low probability Polycomb-mediated chromatin switch, locally at each allele. This switching mechanism is likely to generalise to many processes where complex environmental cues mediate epigenetic regulation. 18 Development and evolution of the land plant-soil interface LIAM DOLAN GMI - Gregor Mendel Institute of Molecular Plant Biology, Dr.-Bohr-Gasse 3, 1030 Wien, Vienna, Austria ABSTRACT Land plants colonized the continental surfaces of the planet approximately 500 million years ago causing dramatic changes to the Earth System. The colonization coincided with the evolution of a suite of adaptations to life in a desiccating atmosphere where plants performed photosynthesis in the air and extracted nutrients and water from the soil. These adaptations include meristems that developed axes like roots and shoots, symbioses with microorganisms, among many others. Rooting structures give plants access to water and nutrients and form a surface at which plants and microbes interact. Comparative morphology suggests that the ancestors of land plants did not form rooting structures. Tip-growing filamentous cells – rhizoids root hairs – develop at the interface between the plant and the soil in the two monophyletic lineages of extant land plants, bryophytes, and vascular plants. This suggests that filamentous rooting cells developed at the plant-soil interface in their last common ancestor. The presence of rhizoids at the plant-soil interface among fossil plants from the Devonian period (258 – 419 million years ago) supports this hypothesis. We show that the ROOT HAIR DEFECTIVE SIX-LIKE (RSL) class I genes likely acted in common ancestor of the land plants. Then RSL class II genes contributed to the development of root hairs in the vascular plant lineage while RSL class III genes contributed to rhizoid development in the bryophyte lineage. Similarly, the repression of RSL class I genes is mediate by the GLABRA2 homeodomain protein in the vascular plant lineage, but by the FEW RHIZOIDS1 (FRH1) miRNA in the bryophyte lineage. These data from comparative morphology, developmental genetics and paleontology demonstrate the existence of a molecular mechanism that acted in the last common ancestor of the land plants that are long since extinct. They also demonstrate how this mechanism evolved independently in different land plant lineages. 19 Breaking the Silence: How to make small plant mouths that support our sustenance KEIKO TORII1,2 1The University of Texas at Austin, HHMI, USA 2Nagoya University, Japan ABSTRACT Stomata, cellular valves on the plant epidermis, serve as critical interface between plant and atmosphere. The presence of stomata are not only critical for plant growth, survival and water-use efficiency but impacts global carbon and water cycles. In addition, stomata are one of the key developmental innovations that enabled plants to conquer terrestrial environment. In the past two decades, molecular genetic studies in the model plant Arabidopsis unraveled the key regulators of stomata differentiation and the mechanism that ensures proper differentiation and patterning of stomata. This involves intricate regulatory circuits amongst cell-cell signaling components, master regulatory transcription factors, polarity components and cell cycle machineries. The master regulatory transcription factors consecutively functions to switch the proliferation to differentiation state of stomatal-lineage cells, and the interplay of transcription factors and epigenetic regulators plays a key role. As we look into the broader implication of what we learned about stomatal development in Arabidopsis to land plants evolution, we now know that many core stomatal genes are conserved in the basal land plants that generate stomata. On the other hand, studies in aquatic grass species suggest extensive gene loss of core stomatal regulators. Thus, whereas acquisition of core stomatal regulatory genes underpin the evolution of plants' life on land, the loss of such genes has implications in plants' life stye to return to under-water environment. These are extreme life-style choice of plants, but what about those plants that strive on fluctuating water environment? We are now looking into how environmental and hormonal signaling pathways are re-wired to regulate stomatal development and how such re- wiring underpins versatile adaptation of plants to environment. ` 20 ICAR2O22 June 20th 1735-1830 Community Resources Session Mary Williams ROOT&SHOOT Project Sarah Black Plantae 2.0 Ros Gleadow Global Plant Council Tanya Berardini Phoenix Bioinformatics Nicholas Provart Bio-Analytic Resource for Plant Biology Marcos Castellanos-Uribe Nottingham Arabidopsis Stock Centre 21 ICAR2O22 June 21st 0900- 1045 Plenary 1: Robustness in Genetic Networks Chair: Claus Schwechheimer, Technical University of Munich, Germany 0900-0930 Siobhan Brady University of California Davis, USA Novelty and Repurposing in Barrier Cell Types In-Person 0930-1000 Peter Etchells Durham University, UK For wood measure: An Arabidopsis vascular development net work In-Person 1000-1030 Alex Leydon University of Washington, USA Re-engineering repression: using synthetic biology to understand and redesign plant form In-Person 1030-1045 Claus Schwechheimer Technical University of Munich, Germany Similar but not the same: Functional conservation and diversification of AGC1 kinases from Arabidopsis thaliana In-Person 1045-1100 Poonam Mehra University of Nottingham, UK Xerobranching: Discovering the mechanisms of root branching under heterogenous water availability In-Person 22 Novelty and Repurposing in Barrier Cell Types CONCEPCION MANZANO, ALEX CANTO-PASTOR and SIOBHAN BRADY Department of Plant Biology and Genome Center, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA ABSTRACT Irrespective of species, plant roots have remarkably similar patterning, and thus, many cell types considered functionally homologous across species. Despite these similarities, there is also diversity in root cell types, such as the exodermis, which is present in a reported 89% of angiosperms, but absent in the intensely studied model species Arabidopsis (Perumalla et al., 1990). In this seminar, I will present our cell type translatome (Kajala et al., 2021), single cell transcriptome and mass CRISPR- Cas9 mutagenesis screens that have revealed the molecular, morphological and functional underpinnings of the tomato root exodermis. These experiments demonstrate that the exodermal developmental program comprises two differentiation stages that produce a lignified and then suberized apoplastic barrier. I will discuss novelty and repurposing of the genes and functions of the tomato exodermal and endodermal barriers relative to the Arabidopsis endodermal barrier. Spray formulations are often traced in the environment by fluorescent tracers. References Kajala K, Gouran M, Shaar-Moshe L, Mason G A, Rodriguez-Medina J, Kawa D, Pauluzzi G, Reynoso M, Canto-Pastor A, Manzano C, Lau V, Artur M A S, West D A, Gray S B, Borowsky A T, Moore B P, Yao A I, Morimoto K W, Bajic M, Formentin E, Nirmal N A, Rodriguez A, Pasha A, Deal R B, Kliebenstein T J, Hvidsten T R, Provart N J, Sinha N R, Runcie D E, Bailey-Serres J, Brady S M. 2021. Cell 184:3333–3348. Perumalla C J, Peterson C A, Enstone D E. 1990. Botanical Journal of the Linnaean Society 103:93–112. 23 For wood measure: An Arabidopsis vascular development network J PETER ETCHELLS Durham University, DH1 3LE, UK ABSTRACT The vascular meristem is somewhat unusual in that it is bifacial in nature. Xylem cells are derived from precursors on one side of the stem cells, while phloem cells form on the opposing side. This arrangement makes the vascular meristem an interesting model for studying developmental biology. Vascular expansion requires tight regulation of rates of cell division within the meristem, and differentiation at its edges to maintain tissue organisation. Cell division and differentiation are under the control of non-cell autonomous signalling. TDIF, a peptide ligand, is expressed in the phloem, and signals to PXY, a receptor kinase expressed in the xylem-adjacent meristem. Active TDIF-PXY complexes promote degradation of differentiation- promoting transcription factors, and activate those that promote cell division. This presentation will discuss how the TDIF-PXY system forms part of a much larger network, and will go on to consider how the components of the network are integrated to balance tissue proliferation with differentiation of xylem and phloem to maintain patterning though growth. References Smit M, et al. 2020. The Plant Cell 32:319-335. Wang N, et al. 2019. Development 146:dev177105. 24 Re-engineering repression: Using synthetic biology to understand and redesign plant form ALEXANDER R LEYDON and JENNIFER L NEMHAUSER University of Washington, Department of Biology, Seattle, WA, USA ABSTRACT Life in our current ‘interesting times’ has many challenges. Among the most urgent is widespread global hunger and malnourishment, made even more difficult by climate crisis. To address this challenge, we must radically innovate the way we conceptualize and execute crop improvement. Synthetic biology, sitting at an intersection of engineering and biology, offers theoretical and practical tools to guide such efforts. In our group, we apply synthetic biology ideas and tools to the fundamental building blocks of plant development—cell-cell communication, cellular differentiation, cell growth and proliferation—with a focus on plant hormones. We have transported the nuclear auxin signaling pathway from Arabidopsis and maize into yeast. Such ‘AuxInYeast’ systems provide a single integrated, inducible, synthetic locus made of readily swappable, engineerable components and easily-quantifiable outputs. These qualities have been highly advantageous for discovering new modes of regulation, building dynamic quantitative models, and beginning to rationally engineer cellular responses. Recently, AuxInYeast has enabled the discovery of a novel and highly conserved molecular mechanism of transcriptional repression that facilitates rapid and coordinated gene activation. In this talk, I will share some of the latest ways we are combining synthetic and developmental biologylocal agricultural conditions. towards the long-term goal of an oen-souce pipeline to customize plant form for 25 Similar but not the same: Functional conservation and diversification of AGC1 kinases from Arabidopsis thaliana CLAUS SCHWECHHEIMER Plant Systems Biology, Technical University of Munich, Freising, Germany ABSTRACT Land plants encode for a number of AGC1 kinases that are evolutionarily derived from the phototropin blue light receptor serine/threonine kinases. The D6PK, D6PKLIKE and PAX AGC1 kinases polarly localize at the plasma membrane where they activate the polarly localized PIN auxin efflux carriers by phosphorylation. The rapid intracellular trafficking to and from the plasma membrane renders AGC1 kinases dynamic regulators of PIN-mediated transport and loss of AGC1 kinases function results in defects in auxin transport-dependent processes like embryo development, root and lateral root development, and tropic responses, to name a few. We have studied the interplay between the different AGC1 kinase family members at the developmental level and will present evidence that D6PK and PAX kinases are functionally diverse and cooperate, in a non-additive manner, in the regulation of protophloem and vascular development. We have further uncovered the regulatory mechanism responsible for the intracellular trafficking and targeting of AGC1 kinases to the polar plasma membrane. References Barbosa I C, Zourelidou M, Willige B C, Weller B, Schwechheimer C. 2014. Dev Cell. 29(6):674–685. Bassukas A E L, Xiao Y, Schwechheimer C. 2022. Curr Opin Plant Biol. 65:102146. Marhava P, Bassukas A E L, Zourelidou M, Kolb M, Moret B, Fastner A, Schulze W X, Cattaneo P, Hammes UZ, Schwechheimer C, Hardtke C S. 2018. Nature 558:297–300. Weller B, Zourelidou M, Frank L, Barbosa I C, Fastner A, Richter S, Jürgens G, Hammes U Z, Schwechheimer C. 2017. Proc Natl Acad Sci USA 114:E887–E896. Zourelidou M, Absmanner B, Weller B, Barbosa I C, Willige B C, Fastner A, Streit V, Port S A, Colcombet J, de la Fuente van Bentem S, Hirt H, Kuster B, Schulze W X, Hammes U Z, Schwechheimer C. 2014. Elife 3:e02860. . 26 Xerobranching: Discovering the mechanisms of root branching under heterogenous water availability POONAM MEHRA and MALCOLM J BENNETT Plant & Crops Sciences, School of Biosciences University of Nottingham, Nottingham NG7 2RD, UK ABSTRACT Water scarcity is a threat to agriculture, given the impact of climate change. Root branching is an agronomically important trait that determines foraging capacity of plants. To adapt to heterogenous soil water availability, roots exhibit tremendous plasticity in their branching patterns. Discovering how plant root sense and continuously adapt to fluctuating water availability at cellular and organ scale is vital for futureproofing crops. Xerobranching provides a model response to study ABA- mediated root adaptive mechanisms to fluctuating soil moisture (Orman et al., 2018). Xerobranching is a root adaptive response where lateral root formation is repressed when roots lose contact with water (e.g. in soil air-gaps). A Xerobranching stimulus triggers the transient release of abscisic acid (ABA) from root phloem tissues. This important water stress signal then moves radially, causing plasmodesmata to close in outer root tissues. Closing these inter-cellular pores disrupts the symplastic movement of auxin, which blocks lateral root branching. Strikingly, once root tips regain contact with moisture, ABA response rapidly attenuates. Xerobranching reveals how dynamic hormone responses enable roots to adapt to heterogeneous soil moisture conditions and reveal molecular targets to re-engineer crops to become more climate resilient. Reference Orman-Ligeza B, et al. 2018. The xerobranching response represses lateral root formation when roots are not in contact with water. Current Biology 28:3165–3173. 27 ICAR2O22 June 21st 1130- 1330 Plenary 2: Epigenetics and Chromatin Biology Chair: Steven Spoel, University of Edinburgh, UK 1130-1200 Yannick Jacob Yale University, USA A silent passenger no more: The H3.1 variant maintains genomic stability during replication In-Person 1200-1230 Sara Farrona University of Galway, Ireland Novel interactors of the polycomb group (PcG) pathway and their role in plant development In-Person 1230-1300 Chang Liu University of Hohenheim, Germany The plant nuclear lamina and its associated chromatin respond to environmental cues Online 1300-1315 Ioanna Kakoulidou Technical University of Munich, Germany Parental pericentromeric methylation status drives methylome remodeling and heterosis in Arabidopsis hybrids In-Person 1315-1330 Charles Seller University of California San Diego, USA Cell-type specific epigenomics reveals abscisic acid (ABA)- triggered genome-wide chromatin remodeling In-Person 28 A silent passenger no more: The H3.1 variant maintains genomic stability during replication HOSSEIN DAVARINEJAD1, YI-CHUN HUANG2, BENOIT MERMAZ2, CHANTAL LEBLANC2, AXEL POULET2, GEOFFREY THOMSON2, VALENTIN JOLY2, MARCELO MUÑOZ3,4, ALEXIS ARVANITIS-VIGNEAULT1, DEVISREE VALSAKUMAR5,6, GONZALO VILLARINO2, ALEX ROSS3,4, BENJAMIN H ROTSTEIN4,7, EMILIO I ALARCON3,4, JOSEPH S BRUNZELLE8, PHILIPP VOIGT5,6, JIE DONG2,9, JEAN-FRANÇOIS COUTURE1 and YANNICK JACOB2 1Ottawa Institute of Systems Biology; Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada 2Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, 260 Whitney Avenue, New Haven, Connecticut 06511, USA 3BEaTS Research Laboratory, Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON K1Y4W7, Canada 4Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada 5Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK 6Epigenetics Programme, Babraham Institute; Cambridge, CB22 3AT, UK 7University of Ottawa Heart Institute, Ottawa, ON K1Y4W7, Canada 8 Feinberg School of Medicine, Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, Illinois 60611, USA 9Institute of Crop Science, Zhejiang University, Hangzhou 310058, China ABSTRACT The replication-dependent H3.1 variant and the replication-independent H3.3 variant are >95% identical in most organisms. Typically, only a single amino acid (position 31) varies between these two histone variants in their N-terminal tails where most of the post-translational modifications on histones are made. Preferential expression and chromatin insertion during DNA replication for the H3.1 variant have been identified ~20 years ago, although a specific role for the H3.1 variant during replication had remained elusive. We will present our new findings regarding the involvement of the H3.1 variant in regulating TSK/TONSL-mediated resolution of stalled or broken replication forks in multicellular eukaryotes. Uncovering this universal function for the H3.1 variant has been made possible by the identification of proteins containing domains capable of specifically writing or reading the H3.1 variant in Arabidopsis thaliana. Overall, our results demonstrate similar strategies in plants and animal systems for confining TSK/TONSL-mediated DNA repair to specific phases of the cell cycle, with both 29 systems using the S-phase-specific H3.1 variant and unrelated histone methyltransferases (ATXR5/ATXR6 in plants and SET8 in animals) to achieve this. The functional characterization of histone H3-variant-specific readers and writers reveal another layer of chromatin-based information regulating transcription, DNA replication and DNA repair in multicellular eukaryotes. 30 Novel interactors of the polycomb group (PcG) pathway and their role in plant development GODWIN JAMES1, ANTOINE FORT2, CLARA BOURBOUSSE3, MICHAL KRZYSZTON4, SZYMON SWIEZEWSKI4, FREDY BARNECHE3, DANIEL SCHUBERT5 and SARA FARRONA1 1National University of Ireland Galway, University Road, Galway, Ireland 2Athlone Institute of Technology, Dublin Road, Kilmacuagh (Cooke), Athlone, Co. Westmeath, Ireland, 3Institut de biologie de l'Ecole normale supérieure (IBENS)-CNRS, 46 Rue d'Ulm, 75005 Paris, France 4Institute of Biochemistry and Biophysics-Polish Academy of Sciences, Adolfa Pawińskiego 5A, 02-106 Warszawa, Poland 5 Freie Universität Berlin, Kaiserswerther Str. 16-18, 14195 Berlin, Germany ABSTRACT Polycomb Repressive Complex 2 (PRC2) represses target genes through the deposition of the highly conserved H3K27me3 epigenetic mark. In Arabidopsis thaliana PWWP DOMAIN INTERACTOR OF POLYCOMBS1 (PWO1) is an interactor and regulator of PRC2, which may also act as mediator of PRC2 repression at the nuclear periphery (Hohenstatt et al., 2018; Mikulski et al., 2019). To further characterise the functions of PWO1, we analysed PWO1 putative complex(es) in planta by co-immunoprecipitation (co-IP) experiments and subsequent liquid chromatography-mass spectrometry (LC-MS/MS). The experiments yielded more than one hundred potential PWO1 interactors (Mikulski et al., 2019). The most abundant protein in our co-IP experiments belongs to the UBIQUITIN PROTEASE (UBP) family (March & Farrona, 2018). Furthermore, our protein-protein interaction data confirm the interaction of this protein to PWO1 and also indicate a direct link to PRC2. Here, we will show transcriptomic, epigenomic and protein-protein interaction data that may help us to understand the molecular activities of this novel interactor during plant development and its role as member of the PWO1-PRC2 protein network. References Hohenstatt M, et al. 2018. Plant Cell 30(1):117–133. March E, Farrona, S. 2018. Frontiers in Plant Science 8:2274. Mikulski P, et al. 2019. Plant Cell 31(5):1141–1154. 31 The plant nuclear lamina and its associated chromatin respond to environmental cues CHANG LIU Institute of Biology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany ABSTRACT The nuclear lamina (NL) is a complex network of nuclear lamins and lamin- associated nuclear membrane proteins, which scaffold the nucleus to maintain structural integrity. In Arabidopsis thaliana, Nuclear Matrix Constituent Proteins (NMCPs) are essential components of the NL and are required for maintaining the structural integrity of the nucleus and specific perinuclear chromatin anchoring. At a chromosomal level, plant chromatin organization in interphase nuclei displays flexibilities. Many developmental cues and environmental factors, such as dedifferentiation, leaf development, seedling growth, floral transition, seed development, light intensity, microbe infection, and temperature stress, can trigger global rearrangement of chromatin, demonstrating a tight connection between the structural arrangement of chromatin and its activities. Based on these observations from Arabidopsis, and given the role of AtNMCP genes (i.e., CRWN1 and CRWN4) in organizing chromatin positioning at the nuclear periphery, one can expect considerable changes in chromatin-NL interactions when the global chromatin organization patterns are being altered in plants. Here, we show that plant nuclear lamina disassembles substantially under various stress conditions. Focusing on heat stress, we revealed that chromatin domains, initially tethered to the nuclear envelope, remained largely associated with CRWN1 and became scattered in the inner nuclear space. We further show that CRWN1 proteins function as negative factors during heat stress to prevent repressed chromatin from being over- decondensed. Also, CRWN1 acts as a negative transcriptional co-regulator to modulate the shift of the plant’s transcriptome profile in response to heat stress. 32 Parental pericentromeric methylation status drives methylome remodeling and heterosis in Arabidopsis hybrids IOANNA KAKOULIDOU1, ROBERT S PIECYK1, RHONDA C MEYER2, THOMAS ALTMANN2 and FRANK JOHANNES1,3 1Technical University of Munich, Department of Molecular Life Sciences, Liesel-Beckmann str.2, Freising, 85354, Germany 2Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Department of Molecular Genetics, Corrensstrasse 3, Gatersleben, 06466, Germany 3Technical University of Munich, Institute for Advanced Study (IAS), Lichtenbergstr. 2a., Garching, 8574, Germany ABSTRACT The DNA methylomes of F1 hybrids undergo substantial remodeling relative to their parents. The extent to which this remodeling can be attributed to specific differentially methylated regions (DMRs) in the parental genomes and the contribution of the DMRs to phenotypic heterosis remain poorly understood (Lauss et al., 2018). Here we present the results of 500 epiHybrid families generated by crossing a male sterile plant to 500 different ddm1-derived epigenetic recombinant inbred lines (epiRILs) (Johannes et al., 2009). Methylome, transcriptome and phenotypic profiling was performed for a number of parents-hybrid trios. Our data reveals that hybrid methylomes display extensive remodeling mainly in non-CG contexts of pericentromeric regions. These remodeling events do not occur in isolation but co- vary substantially among distal regions both within and across chromosomes, thus indicating that methylome remodeling in hybrids is a highly coordinated process. Importantly, we could show that stably segregating parental pericentromeric DMRs (Colomé-Tatché et al., 2012; Cortijo et al., 2014) can be used as predictors of local and distal remodeling events, and that they function as cis- and trans-acting expression quantitative trait loci, which are significantly associated with phenotypic heterosis. Our results establish a model by which parental methylation differences in heterochromatin-rich pericentromeric regions act as major re-organizers of hybrid methylomes and transcriptomes, which - in turn- drive non-additive phenotypic effects contributing to heterosis. References Colomé-Tatché M, et al. 2012. Features of the Arabidopsis recombination landscape resulting from the combined loss of sequence variation and DNA 33