ScreenSYS GmbH
Scientific portrait
Our technology
Cells are the smallest units of life. Plant cells are very special cells in this respect since they have - more immediately than animal cells - the ability to regenerate a complete plant again from a single plant cell. This ultimately happens, for example, when grapevines are propagated by cuttings, in which certain cells of the stem begin to reprogram themselves into root tissue under appropriate conditions, while others begin to grow out into new shoots. This ability is called "totipotency" of plant cells. But even if no propagation from single cells is intended, cells can be isolated alive, for example from leaves, and certain analyses allow conclusions to be drawn about important properties of the entire plant.
ScreenSYS GmbH is a green biotech company specialising in the generation of plants from single cells. It offers innovative solutions for micropropagation of plants, especially recalcitrant (difficult to handle) plant species. To do this, it uses a unique, automated, and AI-driven platform that harnesses the naturally existing totipotency potential from single plant cells to generate complete plants.
This is particularly interesting when the precursors of pollen cells, called microspores, are stimulated to generate plants. Plants generated in this way, known as doubled-haploid plants, have exceptional properties that cannot be produced by classical cross-breeding, or only after very many years.
The technology is based on ground-breaking research conducted at the University of Freiburg, Germany, at the Institute of Molecular Plant Physiology and the Centre for Systems Biology, headed by Prof. Dr. Klaus Palme. ScreenSYS has developed numerous other solutions for improved large-scale handling of single plant cells and has worked with partners from industry and academia to develop innovative approaches for predictive phenotyping of plant cells, which have contributed to the discovery of new chemical regulators in several important crops.
Our contribution to Kliwiresse
Together with the KIT, ScreenSYS GmbH will investigate the extent to which different osmotolerance and heat tolerance of certain grape varieties can be mapped at the level of single cells. This system is based on plant cells in which the cell wall has been removed by enzymatic treatment. In these so-called protoplasts, properties such as viability after various stress treatments and water permeability under osmotic stress are determined via automated microscopy. After calibration with a pair of grapevine genotypes contrasting in osmotolerance, the wild grapevine collection established at KIT will be studied. In parallel, for gene candidates identified as promising on the basis of previous research, suitable cultivars will be selected and specifically investigated with the help of the KIT genome database. The varieties selected in this way are grown as plants and exposed to the corresponding stress conditions. The KliWiResse partner IBMP then extracts the metabolites and investigates them further.
In another subproject within KliWiResse, a protocol is being established that allows the production of doubled-haploid plants from microspores of grapevines. This is done with plant material provided by the partner JKI and associated partner WBI. Since grapevines are propagated vegetatively (i.e., via cuttings), maternal and paternal genes are usually different, which makes breeding very difficult and time-consuming. In contrast, doubled-haploid plants, which are genetically uniform, are the ideal starting material for producing new varieties with improved properties within a short time. The doubled-haploid plants generated in KliWiResse will then be characterised, particularly with regard to their molecular (KIT-BOT) and metabolic (IBMP) stress response. Beyond the breeding of KliWi grapevines, the development of this method will be very beneficial for grapevine breeding as a whole.
What did we achieve
Limelight on the single cell
The response of grapevine to heat stress is composed of several levels. While the responses of entire organs, such as stomatal closure, are investigated by other partners within KliWiResse, we focus on cellular mechanisms, such as increased heat stability of proteins. Such cellular mechanisms are not easily accessible on the level of entire plants. For breeding it would be of utmost importance to recognise such differences in cellular resilience mechanisms.
To reach this goal, we work with two systems: first, we isolate cells from a grapevine cell culture, second, from grapevine leaves. To obtain single cells, the cell walls are enzymatically removed (protoplasting). Those cells remain alive, but their longevity depends on specific factors that, within the intact leaf, would be provided by the other cells to sustain growth and division. Using our automated high throughput microscopy, we can follow thousands of cells over days, by staining them with a fluorescent dye that labels only living cells. Heat treatment accelerates cell death – this is strongly dependent on genotype. We could show that these differences match those observed in the heat resistance of grapevine plants.
Thus, we can link cellular resilience with the resilience of the entire plant. In other words: the protoplast system can be used as experimentally accessible model to test the effect of plant compounds on heat resilience, but also to dissect, who heat stress is sensed and processed.
Use the regenerative abilities of plant cells
The microscopic systems and cultivation media established at ScreenSYS allow to induce the haploid pollen progenitor cells to form a (non-fertilised) embryo, which later is triggered by a specific trick to double its genes. Thus, the plant will become homozygous for all genes. We are currently developing this double haploidisation for grapevine. First, the optimal developmental stage of these cells and the optimal medium needed to be identified. These steps could be completed during the last vegetation period using different stages of developing flowers. Using flowers from the current season, now we test the effect of plant growth regulators and company-owned compounds for the stimulation of cell division. As soon as we arrive at the formation of multicellular structures from single cells, we will prepare the next step – the regeneration of shoots and roots.
Recent publications relevant to the project
Dawson J, Pandey S, Yu Q, Schaub P, Wüst F, Moradi AB, Dovzhenko O, Palme K, Welsch R (2022) Determination of protoplast growth properties using quantitative single-cell tracking analysis. Plant Methods 2022 181 18: 1–15
Falk T, Mai D, Bensch R, Çiçek Ö, Abdulkadir A, Marrakchi Y, Böhm A, Deubner J, Jäckel Z, Seiwald K, et al (2018) U-Net: deep learning for cell counting, detection, and morphometry. Nature Methods 16: 67–70
Middleton AM, Dal Bosco C, Chlap P, Bensch R, Harz H, Ren F, Bergmann S, Wend S, Weber W, Hayashi K-I, et al (2018) Data-Driven Modeling of Intracellular Auxin Fluxes Indicates a Dominant Role of the ER in Controlling Nuclear Auxin Uptake. Cell Rep 22: 3044–3057
Pandey S, Moradi AB, Dovzhenko O, Touraev A, Palme K, Welsch R (2022) Molecular Control of Sporophyte-Gametophyte Ontogeny and Transition in Plants. Front Plant Sci 0: 3358
Welsch R, Touraev A, Palme K (2021) Small molecules mediate cellular reprogramming across two kingdoms. J Exp Bot 72: 7645–7647
