The PSC Symposium 2022 is an initiative of the Zurich Basel Plant Science Center. Our diverse panel of invited speakers will highlight the relevance of spatial organisation in plant sciences from the perspectives of the cellular space, the plant space, the ecosystem space, and even the outer space! We are particularly excited about this year’s edition of the Symposium as after two years of online sessions, it will finally bring the Plant Science Center community back together on site.


  • 7th December 2022
  • ETH Audimax
09:15 - 09:30Welcome By Bruno StuderETH Zurich, PSC chair
09:30 - 10:00The cell space – When it is the right time to divide: parental regulation of cell division during reproduction By Prof. Dr. Sara SimoniniUniversity of Zurich, CH
During the process of fertilization of sexually reproducing organisms, maternal and paternal gametes, egg and sperm respectively, fuses together to give rise to the zygote. Differently from animal, in flowering plants the so-called double fertilization involves a second female gamete, the central cell, from which originates the endosperm, a triploid and ephemeral tissue that nurtures and sustains the growth of the embryo. The fusion of the paternal and maternal gametes generates a series of dramatic events, including the re-activation of the cell cycle that is, somehow, strongly inhibited before fertilization to avoid premature division. Genetic evidences show that both parents exert a tight control over cell cycle progression: the mother reins cell division in the seeds, whereas the father provokes the opposite. The lack of this control then has dramatic and conflicting effects as the development of seed-like structure from unfertilized ovules, or suicidal cell divisions as result of unbalanced DNA content after fertilization. The molecular mechanisms underlying these processes are yet to be fully understood. I will present some of our recent data about the characterization of such mechanisms, showing how maternal factors keep female gametes quiescent, and how paternally-derived signals trigger cell cycle progression specifically at fertilization.
10:00 - 10:30The cell space – A twist in the thale: an update on auxin-mediated cell elongation By Dr. Markus Geisler University of Fribourg, CH
Plants own an amazing high degree of developmental plasticity by regulating cell growth and division in response to internal and external signals. This plasticity is controlled by local maxima and minima of the signalling molecule, auxin. These are generated by the cell-to-cell movement of auxin, a unique process not yet described in non-plant organisms or for other hormones. This so-called polar auxin transport is thought to be mainly provided by the action of auxin exporters of the ABCB and PIN families. Interestingly, abcb loss-of-function mutants reveal a strong developmental phenotype, including a helical, non-handed disorientation of epidermal layers.
In my talk, I will address the morphological and molecular background for this “twisted syndrome” by dissecting the individual roles of ABCB proteins. It appears that all auxin-transporting ABCBs are regulated on the transport level by transient cis-trans isomerization of a conserved and diagnostic D/E-P motif. This catalytic activity is provided by PPIases, including the FKBP42, TWISTED DWARF1. Beside acting as PPIase, TWISTED DWARF1 functions also as a co-chaperone of HSP90 stabilizing ABCBs at the plasma membrane, indicating a dual role during ABCB regulation.
Our findings classify the TWISTED DWARF1-HSP90 module as a positive regulator of polar auxin transport providing plasticity to ABCB-controlled auxin transport and plant development.

10:30 - 11:00The cell space – A journey in spatially resolved transcriptomics: from animal tissues to plants By Dr. Stefania GiacomelloKTH Royal Institute of Technology, Stockholm, SE
Spatial context is fundamental in understanding how tissues are formed and how single cells function and interact together. Most of the available spatial technologies are only available for mammalian tissues limiting the exploration of plant systems. In this talk, I will present our recent developments in Spatial Transcriptomics with a specific focus on plants and microbes.
11:00 - 11:30Coffee break
11:30 - 12:00The plant space – How can Arabidopsis perceive neighbors in space and time? By Dr. Chrysoula PantazopoulouUniversity of Utrecht, NL
Modern agriculture is characterized by the intensification of agricultural practices and cultivation of plants in dense stands. It is crucial for plants growing at high densities to perceive and respond to upcoming shade from a neighboring plant rapidly. The light quality in the canopy is determined by the Red:Far-Red light (R:FR) ratio, with high R:FR indicating sufficient light for photosynthesis and low R:FR indicating shade caused by proximate neighbors. We found previously that leaf tip touching between individuals in a dense vegetation of Arabidopsis is the earliest neighbor detection in shoots. Following touching, the leaves respond with an upward leaf movement (called hyponasty). Due to this hyponastic response the canopy architecture changes from a horizontal to a more vertical one. This vertical alignment of leaves generates FR light reflection, leading to a low R:FR signal inside the canopy. Under these conditions, the plant can detect the low R:FR signal in different parts of the leaves and respond with a further hyponasty and/or elongation of the leaf petiole. All these canopy alterations are part of the shade avoidance strategy of plants to consolidate light capture. Interestingly, touch-induced hyponasty involves a signal transduction pathway that is distinct from light-mediated hyponasty. This indicates that a canopy develops progressively though different signaling pathways towards the final shade avoidance phenotype.
12:00 - 12:30The plant space – Intra- and interplant responses to insect egg deposition in Arabidopsis By Prof. Dr. Philippe Reymond University of Lausanne, CH
Insect eggs deposited on plant leaves are recognized and induce defenses that inhibit egg development or attract egg predators. Oviposition by the Large White butterfly Pieris brassicae leads to salicylic acid accumulation and local cell death in Arabidopsis thaliana. These responses are activated by a phospholipid elicitor perceived at the cell surface and share molecular similarities with generic innate immunity. Surprisingly, we discovered that oviposition inhibits growth of bacterial and fungal pathogens through the establishment of an intra- and interplant systemic acquired resistance (SAR). This finding suggests that eggs manipulate plant signaling by increasing resistance to pathogens, for the potential benefit of feeding larvae.

12:30 - 13:00The plant space – The tri-partite interaction between parasitic plants, host, and their microbiome By Dr. Desalegn Etalo Wageningen University and Research, NL
Plant parasitic weeds belonging to the Orobanchaceae family are the major threat for global food security. They are challenging to control because their life cycle is intimately intertwined with the host physiology. Furthermore, most of the damage on the host occurs while these parasites are at the subterranean life cycle stages. The interaction between the hosts and the parasitic weeds mainly takes place in the rhizosphere where lively microbial activity takes place. However, In the past decades, most studies on host-parasite interactions focused on genetics, biochemistry, and physiology, while the plant-associated microbiome was kept aside, neglecting its value as a source of unmeasured host genetic variation. In my talk, I will discuss the reciprocal interactions between Sorghum and the parasitic weed Striga hermonthica, at the microbiome level, by emphasizing on the impact the microbiome has on the fitness of both the parasite and the host.
13:00 - 14:30Lunch and poster presentations
14:30 - 15:00The ecosystem space – Effects of environmental change on arctic and alpine vegetation By Prof. Dr. Sabine RumpfUniversity of Basel, CH
Climate is currently warming at a rapid pace, causing species to shift their ranges to follow the conditions they are adapted to. In arctic and alpine ecosystems, climate is warming at an even higher pace than the global average. Species range shifts to higher latitudes and elevations are a globally observed consequence, and species richness and vegetation productivity are increasing at highest latitudes and elevations. Yet, the limited empirical evidence available so far suggests that species’ warm range limits shift at least as fast as the cold limits at the global scale, resulting in contracting distributions of many species and, hence, increased extinction risks. Furthermore, both range limits seem to lag behind temperature trends, and the vast majority of publications report considerable amounts of variation between species-specific responses. These idiosyncratic responses imply asynchronous shifts and might result in reshuffled plant communities with novel biotic interactions. An improved understanding of the factors and processes determining the magnitude and velocity of species responses is pressing in a conservation context as arctic and alpine ecosystems harbour disproportionately high biodiversity, including rare and endangered species, and are in general poorly protected.
15:00 - 15:30The ecosystem space – Spatial and temporal variation of forest net primary productivity components on contrasting soils in northwestern Amazon By Prof. Dr. Eliana M. JiménezUniversidad Nacional de Colombia-Sede Amazonia, CO
Climate is a strong determinant of tropical forest productivity; therefore, it is often assumed that Amazonian forest growing on the same local rainfall regime responds similarly to fluctuations in rainfall, independently of soil differences among them. We evaluated intra- and inter-annual variation of net primary productivity (NPP) components, and forest dynamics during 2004–2012 yr in five forests on clay, clay-loam, sandy-clay-loam, sandy-loam and loamy-sand soils, and the same local rainfall regime in northwestern Amazonia (Colombia). The questions were as follows: (1) Do NPP components and forest dynamics respond synchronously to temporal rainfall fluctuations? (2) Are the responses between above and belowground components and forest dynamics similar for different forest stands? A slight and complex synchronicity among different NPP components in their response to temporal rainfall fluctuations were found; few plots showed that aboveground biomass (AGB) and stem growth were susceptible to rainfall fluctuations, while belowground components (fine roots) showed correlation with one-month lagged rainfall. Furthermore, despite that northwestern Amazonia is considered relatively aseasonal, litterfall showed high seasonality in the loam-soil forest group, as well as the fine-root mass, particularly during the 2005 drought. Litterfall correlation with rainfall of sandy-loam terra-firme forest was time lagged as well as fine-root mass of the loamy-sand forest. The correlation between mortality and rainfall was weak, except for the loamy-sand forest (white-sand forest, 77%). High mortality rates occurred in the non-flooded forests for the censuses that included the dry years (2004–2005, 2005–2006). Interestingly, litterfall, AGB increment, and recruitment showed high correlation among forests, particularly within the loam-soil forest group. Nonetheless, leaf area index (LAI) measured in the most contrasting forests (clay and loamy-sand soil) was poorly correlated with rainfall, but highly correlated among them, which could be indicating a phenotypic response to the incident radiation in these sites; also, LAI did not reflect the differences in NPP components and their response to rainfall. Overall, the different temporal behavior of NPP components among forests in relation to rainfall fluctuations suggests the important role that soil exerts on the responses of plant species in each site, besides their effect on forest dynamics and community composition.
15:30 - 16:00Coffee break
16:00 - 17:00Flash talks

Pyrenoid formation in hornworts: genomic hints for green algal-like pyrenoid scaffolding mechanisms

Stephanie Ruaud, Department of Systematic and Evolutionary Botany, University of Zurich

Shared transcriptional response in independent lineages of land plants during plant- cyanobacteria symbiosis shed light on its evolutionary origin

Yuling Yue, Department of Systematic and Evolutionary Botany, University of Zurich

Discriminability of floral colors explains global biogeographical patterns of pollinators

Aphrodite Kantsa, Department of Environmental Systems Science, ETH Zurich

Developing a sampling design for a genetic diversity monitoring program in Switzerland

Oliver Reutimann, Institute of Integrative Biology (IBZ), ETH Zurich
17:00 - 17:30The outer space – Bioregenerative systems to sustain human life for Long-Term Space Missions: the challenges of plant cultivation By Prof. Dr. Stefania de Pascale Università degli studi di Napoli Federico II, IT
Human exploration beyond Low Earth Orbit (LEO) will require technologies regenerating resources like air and water, and producing fresh food while recycling consumables and waste. Bioregenerative Life Support Systems (BLSSs) are artificial ecosystems in which appropriately selected organisms, including bacteria, algae and plants, are assembled in consecutive steps of recycling, to reconvert the crew waste into oxygen, potable water and edible biomass. Plants are considered the most promising biological regenerators to accomplish these functions, thanks to their complementary relationship with humans, however, cultivation in Space requires the knowledge of their response to Space factors (e.g. altered gravity and ionizing radiation) and specific cultivation conditions (e.g. controlled environment, hydroponic systems). The presentation will summarize the research activity carried out at the Department of Agricultural Sciences of the University of Naples Federico II on plant-based BLSSs.
17:30 - 18:00Poster awards and concluding remarks
The best three poster presenters will receive an Award for their top scientific poster.

Assessment criteria: scientific objectivity, contribution to the field, relevance to the conference theme and overall presentation.

Thank you to all who have registered for the PSC Symposium 2022! We are delighted to see the tremendous response to our call for registration and abstract submission :)