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The G protein-coupled estrogen receptor (GPER1) is acknowledged as an important mediator of estrogen signaling. Given the ubiquitous expression of GPER1, it is likely that the receptor plays a role in a variety of malignancies, not only in the classic hormonally regulated tissues (e.g., breast, ovary, and prostate), but also in the colon. As colorectal cancer (CRC) is the third most common cancer in both men and women worldwide and environmental factors and dietary habits are important risk factors, it is increasingly recognized that natural and synthetic hormones and their associated receptors might play a role in CRC. Through oral consumption, environmental contaminants with endocrine activity are in contact with the gastrointestinal mucosa, where they might exert their toxic effects. Although GPER1 has been shown to be engaged in physiological and pathophysiological processes, its role in CRC remains poorly understood. Thus, pro- as well as anti-tumorigenic effects are described in the literature. This thesis has uncovered novel roles of GPER1 in mediating major CRC-associated phenotypes in transformed and non-transformed colon cell lines. Exposure to the estrogens 17β-estradiol (E2), bisphenol-A (BPA) and diethylstilbestrol (DES) but also the androgen dihydrotestosterone (DHT) resulted in GPER1-dependent induction of supernumerary centrosomes, whole chromosomal instability (w-CIN) and aneuploidy. Indeed, both knockdown and inhibition of GPER1 attenuated the generation of (xeno)hormone-driven supernumerary centrosomes and karyotype instability. Mechanistically, (xeno)hormone-induced centrosome amplification was associated with transient multipolar mitosis and the generation of so called anaphase “lagging” chromosomes. The results of this thesis propose a GPER1/PKA/AKAP9-pathway in regulating centrosome numbers in colorectal cancer cells and the involvement of the centriolar protein centrin. Remarkably, exposure to (xeno)hormones resulted in atypical enlargement and unexpected phosphorylation of the centriole marker centrin in interphase. These findings provide a novel role for GPER1 in key CRC-prone lesions and shed light on underlying mechanisms that involve GPER1 function in the colon. Elucidating to what extent centrosomal proteins are involved in the GPER1-mediated aneugenic effect will be an important task for future studies. The present study was intended to lay a first foundation to understand the molecular basis and potential risk factors of CRC which might help to reduce the use of laboratory animals. Since numerous animal experiments are conducted in biomedical research, the development of alternative methods is indispensable. The Federal Institute for Risk Assessment (BfR) as the German Center for the Protection of Laboratory Animals (Bf3R) addresses this issue by uncovering underlying mechanisms leading to colorectal cancer as necessary prerequisite in order to develop alternative methods.
Beinahe 30 Jahre lang glänzte die »Völkerfreundschaft« zwischen Kuba und der DDR im öffentlichen Diskurs der SED als Musterbeispiel ihres proletarischen Internationalismus. Doch die Rhetorik täuscht: Besonders in den Anfangsjahren der bilateralen Beziehungen nahmen die deutschen Kader ihre kubanischen »Genossen« in der Karibik als notorische Querschläger wahr, die mit ihrem Aufbegehren gegen den ideologischen Suprematieanspruch des Kremls die Stabilität des Ostblocks gefährdeten.
Anhand bislang unveröffentlichten Quellenmaterials aus deutschen und kubanischen Archiven veranschaulicht Antonia Bihlmayer die Bemühungen der Regierung Walter Ulbrichts, die widerspenstigen Sozialisten in der Karibik auf Moskau auszurichten. Auf politisch-ideologischer, wirtschaftlicher und kulturpolitischer Ebene analysiert ihre Studie zum einen die Charakteristika dieser sozialistischen Zivilisierungsmission. Zum anderen nimmt sie diejenigen Faktoren in den Blick, die dafür ausschlaggebend waren, dass sich diese beiden sozialistischen Enklaven ab Mitte der 1970er Jahre schließlich zu gleichwertigen »Juniorpartnern« der Sowjetunion entwickelten.
Photosynthesis converts light into metabolic energy which fuels plant growth. In nature, many factors influence light availability for photosynthesis on different time scales, from shading by leaves within seconds up to seasonal changes over months. Variability of light energy supply for photosynthesis can limit a plant´s biomass accumulation. Plants have evolved multiple strategies to cope with strongly fluctuation light (FL). These range from long-term optimization of leaf morphology and physiology and levels of pigments and proteins in a process called light acclimation, to rapid changes in protein activity within seconds. Therefore, uncovering how plants deal with FL on different time scales may provide key ideas for improving crop yield. Photosynthesis is not an isolated process but tightly integrates with metabolism through mutual regulatory interactions. We thus require mechanistic understanding of how long-term light acclimation shapes both, dynamic photosynthesis and its interactions with downstream metabolism. To approach this, we analyzed the influence of growth light on i) the function of known rapid photosynthesis regulators KEA3 and VCCN1 in dynamic photosynthesis (Chapter 2-3) and ii) the interconnection of photosynthesis with photorespiration (PR; Chapter 4).
We approached topic (i) by quantifying the effect of different growth light regimes on photosynthesis and photoprotection by using kea3 and vccn1 mutants. Firstly, we found that, besides photosynthetic capacity, the activities of VCCN1 and KEA3 during a sudden high light phase also correlated with growth light intensity. This finding suggests regulation of both proteins by the capacity of downstream metabolism. Secondly, we showed that KEA3 accelerated photoprotective non-photochemical quenching (NPQ) kinetics in two ways: Directly via downregulating the lumen proton concentration and thereby de-activating pH-dependent NPQ, and indirectly via suppressing accumulation of the photoprotective pigment zeaxanthin.
For topic (ii), we analyzed the role of PR, a process which recycles a toxic byproduct of the carbon fixation reactions, in metabolic flexibility in a dynamically changing light environment. For this we employed the mutants hpr1 and ggt1 with a partial block in PR. We characterized the function of PR during light acclimation by tracking molecular and physiological changes of the two mutants. Our data, in contrast to previous reports, disprove a generally stronger physiological relevance of PR under dynamic light conditions. Additionally, the two different mutants showed pronounced and distinct metabolic changes during acclimation to a condition inducing higher photosynthetic activity. This underlines that PR cannot be regarded purely as a cyclic detoxification pathway for 2PG. Instead, PR is highly interconnected with plant metabolism, with GGT1 and HPR1 representing distinct metabolic modulators.
In summary, the presented work provides further insight into how energetic and metabolic flexibility is ensured by short-term regulators and PR during long-term light acclimation.
Der Untersuchungsgegenstand der vorliegenden Arbeit ist die Praxis der Europäischen Bürgerinitiative (EBI) nach Art. 11 Abs. 4 EUV, dem weltweit ersten und einzigen Instrument transnationaler, partizipativer und digitaler Demokratie. Im Mittelpunkt der Untersuchung steht die Frage, welchen Beitrag die EBI zur weiteren Demokratisierung der EU leisten kann und auf welche Art und Weise insoweit noch weitere Verbesserungen erzielt werden können. Nach zehnjähriger Anwendungspraxis von 2012 bis 2022 liegen inzwischen ausreichend empirische Daten vor, um den Forschungsgegenstand umfassend zu erforschen und das Instrument mit Blick auf seinen von den EU-Institutionen versprochenen Legitimations- und Demokratisierungsbeitrag bewerten zu können. Insbesondere wird das EBI-Verfahren in dieser Arbeit auf seine empirisch nachweisbare Nutzung, auf seine prozedurale Nutzerfreundlichkeit sowie auf seine politische wie rechtliche Wirkmächtigkeit untersucht. Zum Zwecke der korrekten Kategorisierung, Bewertung sowie der nutzerfreundlichen Ausgestaltung des EBI-Verfahrens werden Vergleiche mit Bürger- und Volksinitiativverfahren in den EU-Mitgliedstaaten sowie mit Bürgerbeteiligungsverfahren auf EU-Ebene vorgenommen. Den empirischen und komparativen Analysen werden eine historische Analyse über die Genese der EBI seit dem EU-Verfassungskonvent sowie theoretisch-normative Überlegungen und praktische Untersuchungen zu unterschiedlichen beteiligungszentrierten Demokratiemodellen vorangestellt, um die EBI einzuordnen und die Steigerungsmöglichkeiten ihres Demokratisierungsbeitrags zu erschließen. Letzteres zielt schließlich auf die Frage nach der prozeduralen Kombination und Kompatibilität der EBI mit demokratischen Innovationen aus dem Bereich der deliberativen und direkten Demokratie ab. Die Arbeit schließt mit einem Ausblick und unterbreitet umfassende EBI-Reformoptionen sowohl auf der primär- und sekundärrechtlichen als auch auf der informellen Ebene.
Funken
(2023)
Bereits im vorschulischen Bereich, aber vor allem in der Grundschule entwickeln Kinder wichtige Kompetenzen für spätere Bildungsabschlüsse. Doch die Kompe-tenzunterschiede zwischen den Schüler:innen sind bereits zu Beginn der Grund-schulzeit beträchtlich. Somit kommt den Lehrkräften die überaus wichtige Aufga-be zu allen Kindern den für sie besten Bildungsweg zu ermöglichen. Um dieser Herausforderung zu begegnen, müssen Diagnostik und Förderung im Unterricht Hand in Hand gehen. Deshalb wird die Diagnosekompetenz von Lehrkräften als wichtige Voraussetzung für gelingenden Unterricht angesehen. Diese Dissertation widmet sich nun eben dieser wichtigen Kompetenz. Dabei wird sie als mehrdimen-sionales Konstrukt angesehen, zu dem neben der Beurteilung von fachlichen Kompetenzen auch die Einschätzung des Leistungsstandes und die Schlussfolge-rung hinsichtlich notwendiger Förderung im Unterricht gehören. Anhand dreier Artikel sowie ergänzender theoretischer Betrachtungen wurde die Diagnosekompe-tenz hinsichtlich möglicher Einflussfaktoren, der Bedeutung für den Unterricht sowie für die Lehrer:innenbildung untersucht.
De/lirios
(2023)
En base al concepto de "de/lirio", que articula trastornos en la enunciación literaria en primera persona, por un lado, con la caracterización psicopatológica de este yo enunciativo, por otro lado, el estudio explora las "líricas desviadas" de Mario Levrero y Alberto Laiseca, y muestra como responden productivamente a problemáticas estéticas, éticas y ontológicas propias de la vuelta del milenio, en el Río de la Plata y más allá.
The light reactions of photosynthesis are carried out by a series of multiprotein complexes embedded in thylakoid membranes. Among them, photosystem I (PSI), acting as plastocyanin-ferderoxin oxidoreductase, catalyzes the final reaction. Together with light-harvesting antenna I, PSI forms a high-molecular-weight supercomplex of ~600 kDa, consisting of eighteen subunits and nearly two hundred co-factors. Assembly of the various components into a functional thylakoid membrane complex requires precise coordination, which is provided by the assembly machinery. Although this includes a small number of proteins (PSI assembly factors) that have been shown to play a role in the formation of PSI, the process as a whole, as well as the intricacy of its members, remains largely unexplored.
In the present work, two approaches were used to find candidate PSI assembly factors. First, EnsembleNet was used to select proteins thought to be functionally related to known PSI assembly factors in Arabidopsis thaliana (approach I), and second, co-immunoprecipitation (Co-IP) of tagged PSI assembly factors in Nicotiana tabacum was performed (approach II).
Here, the novel PSI assembly factors designated CO-EXPRESSED WITH PSI ASSEMBLY 1 (CEPA1) and Ycf4-INTERACTING PROTEIN 1 (Y4IP1) were identified. A. thaliana null mutants for CEPA1 and Y4IP1 showed a growth phenotype and pale leaves compared with the wild type. Biophysical experiments using pulse amplitude modulation (PAM) revealed insufficient electron transport on the PSII acceptor side. Biochemical analyses revealed that both CEPA1 and Y4IP1 are specifically involved in PSI accumulation in A. thaliana at the post-translational level but are not essential. Consistent with their roles as factors in the assembly of a thylakoid membrane protein complex, the two proteins localize to thylakoid membranes. Remarkably, cepa1 y4ip1 double mutants exhibited lethal phenotypes in early developmental stages under photoautotrophic growth. Finally, co-IP and native gel experiments supported a possible role for CEPA1 and Y4IP1 in mediating PSI assembly in conjunction with other PSI assembly factors (e.g., PPD1- and PSA3-CEPA1 and Ycf4-Y4IP1). The fact that CEPA1 and Y4IP1 are found exclusively in green algae and higher plants suggests eukaryote-specific functions. Although the specific mechanisms need further investigation, CEPA1 and Y4IP1 are two novel assembly factors that contribute to PSI formation.
Das menschenrechtliche Prinzip des Non-Refoulement vor den Vertragsorganen der Vereinten Nationen
(2023)
Die Vertragsorgane der Vereinten Nationen können durch die Abstimmung ihrer Praxis Rechtssicherheit schaffen, und zwar sowohl für Betroffene als auch für die Vertragsstaaten. Durch den ständigen Dialog mit den Vertragsstaaten, die Beeinflussung der Vertragsorgane untereinander und das Aufgreifen der Praxis durch andere internationale Akteure lässt sich Gewohnheitsrecht identifizieren. -- Dabei ist das menschenrechtliche Prinzip des Non-Refoulement besonders geeignet, dieses Potenzial der Vertragsorgane zu veranschaulichen. Hierbei handelt es sich um ein Rechtsprinzip, das zwar dem Grunde nach allgemein anerkannt ist, dessen Reichweite im Detail jedoch kontinuierlich umstritten ist. Erstmals wird ein umfassender Überblick über die gesamte Praxis der Vertragsorgane zum Prinzip des Non-Refoulement gegeben. Es wird gezeigt, wie sich die Vertragsorgane sowohl auf prozessualer Ebene als auch bei der Bestimmung des materiellen Schutzbereichs von Refoulementverboten einander annähern.
The digitization has permeated almost all aspects of an individual’s life. In the work context as well as in the private sphere, one readily encounters and relies on Information and Communication Technologies (ICTs), such as Social Networking Sites (SNS), smartphones and so forth. By communicating with as well as obtaining information via such technologies, ICTs engage one’s mind as interaction happens. This interaction of ICTs and the human mind form the focal topic of this thesis. Within this thesis, the human mind is represented on behalf of a facilitated model comprising a perceptual, a cognitive and a motor subsystem. ICTs represent an external stimulus, which triggers the human mind's perceptual subsystem, the cognitive subsystem and eventually leads to a motoric response via the motor subsystem. The external stimulus causing this event chain is within this thesis an ICT. The digital environment and related ICTs are high attention environments offering large and easily accessible amounts of information. Not surprisingly, issues may arise, when the human mind deals with ICTs. Thus, the interplay between ICTs and the human mind entails downsides. This thesis investigates these downsides and in addition the ICT-based factors that cause these downsides. More specifically, the thesis investigates these two aspects as research questions in the context of SNSs as well as other ICTs (such as smartphones, e-learning etc.). Addressing the research questions, 8 articles are submitted within this thesis which address the topic with different methodologies, including quantitative, qualitative, mixed methods as well as systematic literature reviews. Article 1 investigates factors that lead to SNS fatigue and discontinuance intentions in a mixed-methods design. Article 2 explores if certain factors encountered on a newsfeed hamper sensemaking. Article 3 proposes a study design to explore the link between disorderly perceptions of a SNSs newsfeed and gender stereotype activations. Article 4 considers the interplay between users and algorithms via the newsfeed interface and the implications for relevance perceptions. Article 5 explores information acquisition, hampering factors and verification strategies of social media users. Article 6 systematically reviews addiction scales of various ICTs. Article 7 investigates click behavior in e-learning contexts and how this is linked to cultural and personality traits. Finally, article 8 offers a comprehensive overview of the antecedents and consequences of children’s smartphone usage. Within the specific context of SNSs, the thesis suggests that the cognitive tolls imposed on users’ minds cause adverse effects, such as impaired sensemaking, fatigue, stereotype activation as well as intentions to discontinue the service. Other ICTs lead to addiction, and i.e., smartphones evidence to cause cognitive impairments in children. Factors on the ICT side that promote these adverse effects are linked to specific features, such as the newsfeed for SNSs and entail overload or perceptions of disorder. The thesis adds theoretically to the understanding of downsides that arise from the interplay between human minds and ICTs. Especially, the context of SNSs is spotlighted and insights add to the growing body of literature on experiences and perceptions. For instance, one study’s result suggests that considering information organization is as important as merely decreasing overload perceptions from the users in countering adverse effects of SNS usage. Practically, the thesis emphasizes the importance of mindful interaction with ICTs. Future research is welcome to build on the exploratory investigations and may draw an even more holistic picture to enhance the interaction between ICTs and the human mind.
The musculoskeletal system provides support and enables movement to the body, and its deterioration is a crucial aspect of age-related functional decline. Mesenchymal stromal cells (MSCs) play an important role in musculoskeletal homeostasis due to their broad differentiation potentials and their ability to support osteogenic and myogenic tissue maintenance and regeneration. In the bone, MSCs differentiate either into osteochondrogenic progenitors to form osteocytes and chondrocytes, or increasingly with age into adipogenic progenitors which give rise to bone-resident adipocytes. In skeletal muscle, during healthy regeneration MSCs provide regulatory signals that activate local, tissue-specific stem cells, known as satellite cells, which regenerate contractile myofibres. This process involves a significant cross-talk to immune cells stemming from both lymphoid and myeloid lineages. During ageing, muscle-resident MSCs undergo increased adipogenic lineage commitment, causing niche changes that contribute to fatty infiltration in muscles. These shifts in cell populations in bone lead to the loss of osteogenic cells and subsequently osteoporosis, or in muscle to impaired regeneration and to the development of sarcopenia. However, the signals that drive transition of MSCs into their respective cellular fates remain elusive.
This thesis aims to elucidate the transcriptional shifts modulating cell states and cell types in musculoskeletal MSC fate determination. Single-cell RNA-sequencing (scRNA-seq) was used to characterise cell type-specific transcript regulation. State-of-the-art bioinformatics tools were combined with different analytical platforms that include both droplet-based scRNA-seq for large heterogeneous populations, and microfluidics-based scRNA-seq to assess small, rare subpopulations. For each platform, distinct computational pipelines were established including filtering steps to exclude low-quality cells, and data visualisation was performed by dimensionality reduction. Downstream analysis included clustering, cell type annotation, and differential gene expression to investigate transcriptional states in defined cell types during ageing and injury in the muscle and bone. Finally, a novel tool to assess publication activities in defined areas of research for the identified marker genes was developed.
The results in the bone indicate that ageing MSCs increasingly commit towards an adipogenic fate at the expense of osteogenic specialisation. The data also suggests that significant cell population shifts of MSC-type fibro-adipogenic progenitors during muscle ageing underlie the pathologies observed in homeostatic and post-injury regenerative conditions. High-throughput visualisation of publication activity for candidate genes enabled more effective biological evaluation of scRNA-seq data. These results expose critical age-related changes in the stem cell niches of skeletal muscle and bone, highlight their respective sensitivity to nutrition and pathology, and elucidate novel factors that modulate stem cell-based regeneration. Targeting these processes might improve musculoskeletal health in the context of ageing and prevent the negative effects of pathological lineage determination.
Pichia pastoris (syn. Komagataella phaffi) is a distinguished expression system widely used in industrial production processes. Recent molecular research has focused on numerous approaches to increase recombinant protein yield in P. pastoris. For example, the design of expression vectors and synthetic genetic elements, gene copy number optimization, or co-expression of helper proteins
(transcription factors, chaperones, etc.). However, high clonal variability of transformants and low screening throughput have hampered significant success.
To enhance screening capacities, display-based methodologies inherit the potential for efficient isolation of producer clones via fluorescence-activated cell sorting (FACS). Therefore, this study focused on developing a novel clone selection method that is based on the non-covalent attachment of Fab fragments on the P. pastoris cell surface to be applicable for FACS.
Initially, a P. pastoris display system was developed, which is a prerequisite for the surface capture of secreted Fabs. A Design of Experiments approach was applied to analyze the influence of various genetic elements on antibody fragment display. The combined P. pastoris formaldehyde dehydrogenase promoter (PFLD1), Saccharomyces cerevisiae invertase 2 signal peptide (ScSUC2), - agglutinin (ScSAG1) anchor protein, and the ARS of Kluyveromyces lactis (panARS) conferred highest display levels.
Subsequently, eight single-chain variable fragments (scFv) specific for the constant part of the Fab heavy or light chain were individually displayed in P. pastoris. Among the tested scFvs, the anti-human CH1 IgG domain scFv allowed the most efficient Fab capture detected by flow cytometry.
Irrespective of the Fab sequence, exogenously added as well as simultaneously secreted Fabs were successfully captured on the cell surface. Furthermore, Fab secretion capacities were shown to correlate to the level of surface-bound Fabs as demonstrated for characterized producer clones.
Flow-sorted clones presenting high amounts of Fabs showed an increase in median Fab titers (factor of 21 to 49) compared to unsorted clones when screened in deep-well plates. For selected candidates, improved functional Fab yields of sorted cells vs. unsorted cells were confirmed in an upscaled shake flask production. Since the scFv capture matrix was encoded on an episomal plasmid with inherently unstable autonomously replicating sequences (ARS), efficient plasmid curing was observed after removing the selective pressure. Hence, sorted clones could be immediately used for production without the need to modify the expression host or vector. The resulting switchable display/secretion system provides a streamlined approach for the isolation of Fab producers and subsequent Fab production.
Unveiling the Local Universe
(2023)
Fördern und Zensieren
(2023)
Deutsche Blauhelme in Afrika
(2023)
Warum trat die Bundesregierung ab Ende der 1980er Jahre weltweit als sicherheitspolitischer Akteur in Erscheinung? Warum engagierte sie sich in multinationalen Missionen der Vereinten Nationen etwa in Somalia, Namibia und Ruanda mit Soldaten oder Polizisten - und in anderen Missionen in Afrika im gleichen Zeitraum nicht? Gestützt auf ministerielle Archivquellen untersucht Torsten Konopka die Prozesse der nationalen Entscheidungsfindung, die zu einer Beteiligung oder Nichtbeteiligung an VN-Missionen in Afrika führten. Das Buch leistet einen politik- sowie militärgeschichtlichen Beitrag zur Genese der frühen Auslandsverwendungen der Bundeswehr.
Aging is a complex process characterized by several factors, including loss of genetic and epigenetic information, accumulation of chronic oxidative stress, protein damage and aggregates and it is becoming an emergent drug target. Therefore, it is the utmost importance to study aging and agerelated diseases, to provide treatments to develop a healthy aging process. Skeletal muscle is one of the earliest tissues affected by age-related changes with progressive loss of muscle mass and function from 30 years old, effect known as sarcopenia. Several studies have shown the accumulation of protein aggregates in different animal models, as well as in humans, suggesting impaired proteostasis, a hallmark of aging, especially regarding degradation systems. Thus, different publications have explored the role of the main proteolytic systems in skeletal muscle from rodents and humans, like ubiquitin proteasomal system (UPS) and autophagy lysosomal system (ALS), however with contradictory results. Yet, most of the published studies are performed in muscles that comprise more than one fiber type, that means, muscles composed by slow and fast fibers. These fiber types, exhibit different metabolism and contraction speed; the slow fibers or type I display an oxidative metabolism, while fast fibers function towards a glycolytic metabolism ranging from fast oxidative to fast glycolytic fibers. To this extent, the aim of this thesis sought to understand on how aging impacts both fiber types not only regarding proteostasis but also at a metabolome and transcriptome network levels. Therefore, the first part of this thesis, presents the differences between slow oxidative (from Soleus muscle) and fast glycolytic fibers (Extensor digitorum longus, EDL) in terms of degradation systems and how they cope with oxidative stress during aging, while the second part explores the differences between young and old EDL muscle transcriptome and metabolome, unraveling molecular features. More specifically, the results from the present work show that slow oxidative muscle performs better at maintaining the function of UPS and ALS during aging than EDL muscle, which is clearly affected, accounting for the decline in the catalytic activity rates and accumulation of autophagy-related proteins. Strinkingly, transcriptome and metabolome analyses reveal that fast glycolytic muscle evidences significant downregulation of mitochondrial related processes and damaged mitochondria morphology during aging, despite of having a lower oxidative metabolism compared to oxidative fibers. Moreover, predictive analyses reveal a negative association between aged EDL gene signature and lifespan extending interventions such as caloric restriction (CR). Although, CR intervention does not alter the levels of mitochondrial markers in aged EDL muscle, it can reverse the higher mRNA levels of muscle damage markers. Together, the results from this thesis give new insights about how different metabolic muscle fibers cope with age-related changes and why fast glycolytic fibers are more susceptible to aging than slow oxidative fibers.
Potato FLC-like and SVP-like proteins jointly control growth and distinct developmental processes
(2023)
Based on worldwide consumption, Solanum tuberosum L. (potato) is the most important non-grain food crop. Potato has two ways of stable propagation: sexually via flowering and vegetatively via tuberization. Remarkably, these two developmental processes are controlled by similar molecular regulators and mechanisms. Given that FLC and SVP genes act as key flowering regulators in the model species Arabidopsis and in various other crop species, this study aimed at identifying FLC and SVP homologs in potato and investigating their roles in the regulation of plant development, with a particular focus on flowering and tuberization. Our analysis demonstrated that there are five FLC-like and three SVP like proteins encoded in the potato genome. The expression profiles of StFLCs and StSVPs throughout potato development and the detected interactions between their proteins indicate tissue specificity of the individual genes and distinct roles of a variety of putative protein complexes. In particular, we discovered that StFLC-D, as well as StFLC-B, StSVP-A, and StSVP-B play a complex role in the regulation of flowering time, as not only increased but also decreased levels of their transcripts promote earlier flowering. Most importantly, StFLC-D has a marked impact on tuberization under non-inductive conditions and susceptibility to temperature-induced tuber malformation, also known as second growth. Plants with decreased levels of StFLC-D demonstrated a strong ability to produce tubers under long days and appeared to be insensitive to temperature-induced second growth. Lastly, our data also suggests that StFLCs and StSVPs may be involved in the nitrogen-dependent regulation of potato development. Taken together, this study highlights the functional importance of StFLC and StSVP genes in the regulation of distinct developmental processes in potato.
Spur der Scherben
(2023)