@phdthesis{DELONGHI2024, author = {DE LONGHI, Emilio}, title = {Sensory and chemical characterization of the aroma of Riesling wines}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-1121}, school = {Hochschule Geisenheim University}, pages = {i -- XXIX}, year = {2024}, abstract = {Riesling wines are appreciated for their diverse and distinctive aromas, resulting from complex interactions of their numerous volatile components with human olfactory system. However, the volatile composition associated with the aroma properties of Riesling wines has not been fully understood. The aim of this thesis was to advance the characterization of Riesling wine volatile composition, through analytical and sensory approaches. Focusing on the thiol component of Riesling wine, sensory-guided screening by heart-cutting multidimensional gas chromatography mass spectrometry/olfactometry (H/C MDGC-MS/O) of Riesling wine thiol selective extracts, obtained by Ag+ solid-phase extraction (Ag+ SPE), followed by Riesling wine thiol analysis by ultra high-performance liquid chromatography (UHPLC) quadrupole Orbitrap high-resolution mass spectrometry (HRMS) in parallel reaction monitoring (PRM), enabled the identification of twelve volatile odorant thiol candidates in Riesling wine (3-sulfanylhexan-1-ol, 3-sulfanylheptan-1-ol, 3-sulfanylhexyl acetate, 4-methyl- 4-sulfanylpentan-2-one, ethyl 3-sulfanylpropionate, ethyl 2-sulfanylpropionate, trans-2- methyl-3-tetrahydrofuranthiol, 2-methyl-3-furanthiol, benzenemethanethiol, o-toluenethiol, mtoluenethiol, and 2-furfurylthiol). LC-MS analysis empowered to quantify the twelve thiols in a set of Riesling wines (n = 33), highlighting their occurrence at concentrations reaching sensory detection threshold values. Additionally, it allowed the detection of two new monoterpenoid thiols 1-p-menthene-8-thiol and trans-p-menthane-3-one-8-thiol in wine for the first time, two compounds possessing respectively grapefruit and blackcurrant aroma nuances. The odor thresholds of these thiols in model wine were determined at 0.076 ng/L and 22.9 ng/L, respectively. The employed LC-MS analytical method was newly developed for the quantitation of ultra-trace volatile thiols in wine. The proposed procedure, consisting of thiol derivatization by 4,4'-dithiodipyridine (DTDP), followed by thiol-DTDP derivatives isolation by liquid-liquid extraction, allowed rapid sample preparation. Instrument analysis performed using UHPLC quadrupole Orbitrap HRMS offered ultra-selectivity and sensitivity for 19 selected thiols. The analytical performances of the novel method were observed in most cases greater than those of previously developed methods. A comprehensive investigation of the links between volatile composition and sensory properties of Riesling wine was then conducted, combining sensory descriptive analysis with quantitative chemical data from a selection of Riesling wines from Germany and France (n = 27). The results from the quantitative chemical analysis of 77 volatile compounds and 14 basic wine parameters were merged with the sensory scores obtained from the descriptive analysis of the collected wine samples by a German-based experienced panel (n = 18) through partial least squares (PLS) regression. The analyzed volatiles spanned from different molecular families known for their relevance for Riesling wine aroma and included monoterpenes, C13-norisoprenoids, higher alcohols, acetate esters, fatty acid ethyl esters, lactones, light volatile sulfur compounds, and polyfunctional thiols. Selected compounds with higher regression coefficients in relation to Riesling aromatic typicality scoring were supplemented in Riesling wine, up to concentration levels reached by the most typical ranked wines, and were found to be associated with a significant increase of Riesling olfactory typicality perceived by experienced sensory judges (n = 15). Overall, this work has advanced the knowledge about molecular drivers of aroma perception of Riesling wines, pointing out the role of novel potent polyfunctional thiols, in association to other major aroma components of Riesling wines. These findings offer promising prospects for the winemaking industry and for future advancements in Riesling wine aroma research.}, language = {en} } @phdthesis{Hauck2024, author = {Hauck, Katharina}, title = {Challenges of the organic wine sector - A value chain analysis of organic wine in Germany}, volume = {2024}, number = {99}, edition = {1. Auflage}, publisher = {Geisenheimer Berichte}, address = {Geisenheim}, isbn = {ISBN 978 3 934742 91 8}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-898}, school = {Hochschule Geisenheim University}, pages = {II -- 95}, year = {2024}, abstract = {The demand for organic products is continuously increasing, with Germany's organic market reaching 15.9 billion euros, making it the second largest in the world. Concurrently, the organically farmed area in Germany is also expanding. The German wine industry is similarly affected, with the share of organic viticulture more than doubling over the past decade. However, there is a notable disparity in the demand for organic wine compared to other organic foods. This dissertation aims to explain the discrepancy between the increasing area of organically cultivated vineyards and the lack of conscious purchasing of organic wine. The research project investigates the entire value chain of organic wine using qualitative and quantitative methods. It surveys producers about their attitudes and motivations behind converting vineyards to organic farming, and includes feedback from traders to define consumer preferences and future market developments. The study also examines the end consumer's perspective to understand why organic wine is not consciously perceived and purchased. The findings reveal that personal conviction drives winegrowers to switch to or maintain organic farming, but low demand is offset by challenging production conditions and higher costs. Traders are interested in organic wine only if there is demand, and their limited knowledge hinders consumer education.}, language = {de} } @phdthesis{Fackert2024, author = {Fackert, Marcel Monti}, title = {Analyse und Gestaltung der Logistikprozesse in der deutschen Qualit{\"a}tsschaumweinindustrie unter besonderer Ber{\"u}cksichtigung von Digitalisierung und Automatisierung}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-1131}, school = {Hochschule Geisenheim University}, pages = {I -- 230}, year = {2024}, abstract = {Diese Dissertation untersucht die logistischen Zusammenh{\"a}nge in den Wertsch{\"o}pfungsstufen der Qualit{\"a}tsschaumweinindustrie in Deutschland. Der Absatz und die Herstellung von Qualit{\"a}tsschaumwein ist im Betrachtungs-zeitraum von 2002 bis heute stetig gestiegen und hat sich im Volumensegment bereits auf wenige große Hersteller konsolidiert. Die Marktstruktur und -teil-nehmer werden aufgezeigt und ihre Motivation hinsichtlich Umsatz, Menge und Herstellqualit{\"a}t genau beschrieben. Die neu entwickelte Sekt Supply Chain visualisiert die verschiedenen logistischen Wertsch{\"o}pfungsketten von der Traube bis zum fertigen Sekt {\"u}ber die Schritte des eigenen Anbaus bzw. dem Zukauf von Rohstoffen, den verschiedenen Herstellungsverfahren und Lagerhaltungsm{\"o}glichkeiten bis hin zur Distribution. Durch explorative Experteninterviews werden logistische Trends in der Digitalisierung, Automatisierung und Nachhaltigkeit f{\"u}r die Branche bewertet. Digitalisierung findet zwar in fast allen Unternehmen statt, jedoch mit unterschiedlichen Ans{\"a}tzen. F{\"u}r alle gemein ist die effizientere Herstellung auf Basis von Echtzeitdaten und Reduzierung der Durchlaufzeiten und Losgr{\"o}ßen f{\"u}r schnellere Reaktionszeiten mit weniger Best{\"a}nden. Die Sekthersteller kommen digital n{\"a}her an den Kunden und produzieren bedarfsgenauer. Bei Sektmanufakturen ist durchg{\"a}ngig ein gesteigertes Qualit{\"a}tsniveau festzustellen, wobei traditionelle Methoden nicht im Widerspruch zur Automatisierung von Prozessschritten zur Steigerung der Flexibilit{\"a}t und Reduzierung von Kapazit{\"a}tskosten wie Personaleinsatz stehen. In der Sekt Supply Chain gibt es in den einzelnen Logistikprozessen viel Optimierungspotential. Dies wird mit zwei Detailbeispielen, der Reduzierung von Verschwendung bei der schlanken Traubenanlieferung des Badischen Winzerkellers und bei der bedarfs- bzw. bestandsoptimierten Prognose bei Rotk{\"a}ppchen-Mumm mit Hilfe des Advanced Planning mit einer daf{\"u}r entwickelten mathematischen Formel aufgezeigt. Trotz aller unternehmensspezifischer Unterschiede und der Heterogenit{\"a}t des deutschen Sektmarktes gibt es doch Gemeinsamkeiten in den logistischen Prozessen unter dem Einfluss der Digitalisierung und Automatisierung.}, language = {de} } @phdthesis{Dahlmann2024, author = {Dahlmann, Melanie}, title = {Entwicklung eines innovativen Fallendesigns f{\"u}r ein Attract-and-Kill Verfahren zur nachhaltigen Bek{\"a}mpfung der Kirschessigfliege Drosophila suzukii im Obst- und Weinbau}, volume = {2025}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-1077}, school = {Hochschule Geisenheim University}, pages = {436}, year = {2024}, abstract = {Seit 2008 verursacht die Kirschessigfliege Drosophila suzukii (MATSUMURA 1931) (Diptera: Drosophilidae) aufgrund ihrer polyphagen Lebensweise nicht nur in Europa hohe wirtschaft-liche Verluste vor allem im Stein- und Beerenobstanbau, aber auch im Weinbau. Die invasive Art hat sich weltweit rasant ausgebreitet, vor allem {\"u}ber den Export von Fr{\"u}chten. Eine hohe Vermehrungsrate und die Anpassung an klimatische Bedingungen machen diesen Sch{\"a}dling zu einem ernsthaften Problem f{\"u}r den Pflanzenschutz in Obst- und Weinbaugebieten. Im Gegensatz zu monophag lebenden Schaderregern, stellt die polyphage Lebensweise der Kirschessigfliege eine weitere Herausforderung f{\"u}r eine gezielte und nachhaltige Bek{\"a}mpfung dar. F{\"u}r eine fr{\"u}hzeitige Prognose von Schadschwellen und eine effiziente Bek{\"a}mpfung von D. suzukii, z. B. durch den Einsatz von Insektiziden, ist daher die Kenntnis {\"u}ber biologische Verhaltensparameter sowie {\"U}berwinterungs- und R{\"u}ckzugsgebiete, aus denen der Schadorga-nismus in die Obst- und Weinberge migriert, von großer Bedeutung. In Deutschland wurden bereits mehr als 50 Wirtspflanzen aus Kultur- und Wildpflanzen als Vermehrungshabitat identifiziert. Aufgrund des anhaltenden Mangels an alternativen Methoden zur Bek{\"a}mpfung von D. suzukii, ist auch das Wissen um die Wirksamkeit von Insektiziden entscheidend f{\"u}r ein optimal angepasstes Bek{\"a}mpfungsmanagement. Ziel der vorliegenden Dissertation war es, visuelle und olfaktorische Lockmittel f{\"u}r eine nachhaltige und umweltfreundliche Bek{\"a}mpfungsstrategie gegen Drosophila suzukii zu ent-wickeln, die auf der Methode des Attract-and-Kill (engl. Anlocken-und-Abt{\"o}ten) Verfahrens basiert. Der Schwerpunkt lag auf der Entwicklung eines geeigneten Fallendesigns und eines attraktiven K{\"o}ders, welcher in Kombination mit einem (biologischen) insektiziden Wirkstoff als Fraßk{\"o}der in Fangfallen oder zur Blattapplikation verwendet werden k{\"o}nnte. Die Kombi-nation aus Lockstoff und Insektizid soll dazu beitragen, den Einsatz von Pflanzenschutz-mitteln zu reduzieren und die Vermehrungsrate von D. suzukii nachhaltig zu senken. Im Rahmen der vorliegenden Dissertation ist es gelungen, ein Fallendesign zu entwickeln, das insbesondere f{\"u}r Drosophila suzukii Weibchen attraktiv ist. Das Design, welches auf kugel-f{\"o}rmigen Objekten in unterschiedlichen Farben auf rotem Hintergrund basiert, zeigte eine geschlechterspezifische Attraktivit{\"a}t durch eine signifikant h{\"o}here Anzahl weiblicher Indi-viduen im Vergleich zu D. suzukii M{\"a}nnchen innerhalb der Falle. Diese positive Eigenschaft des neuen Fallendesigns wurde in Gew{\"a}chshaus- und Halbfreilandversuchen festgestellt und war ebenfalls unter Freilandbedingungen reproduzierbar. Die Entwicklung eines Fraßk{\"o}ders (Phagostimulans) aus weitestgehend nat{\"u}rlichen Inhaltsstoffen zeigte unter Laborbedingun-gen vielversprechende Ergebnisse f{\"u}r einen m{\"o}glichen Einsatz im Rahmen eines Attract-and-Kill Verfahrens, z. B. als Fraß-, bzw. Eiablagek{\"o}der. Der K{\"o}der zeigte eine hohe Attraktivit{\"a}t im Vergleich zu einer nat{\"u}rlichen Wirtsfrucht (Choice-Test) sowie eine Wirkung auf die Mortalit{\"a}tsrate adulter D. suzukii (M{\"a}nnchen 99 \% und Weibchen 70 \% Mortalit{\"a}t nach 72 h im Vergleich zur unbehandelten Kontrolle). Dar{\"u}ber hinaus konnte ein Einfluss des Fraß-Eiablage-K{\"o}ders auf die larvale Entwicklung und eine Verringerung der Verpuppungsrate nachgewiesen werden. Erg{\"a}nzend zu der Entwicklung m{\"o}glicher Lockstoffe f{\"u}r den Einsatz im Attract-and-Kill Verfahren wurden Laborversuche mit adulten D. suzukii und L1-Larven durchgef{\"u}hrt, um die Wirksamkeit verschiedener Pr{\"u}fsubstanzen auf die Fekundit{\"a}t, Repro-duktionsrate sowie die Mortalit{\"a}t zu untersuchen. Die Versuche mit dem Wirkstoff Azadirachtin A (NeemAzal® technical, NeemAzal®-T/S) zeigten nach oraler Aufnahme einen Effekt auf die Fekundit{\"a}t und auf den Larvenschlupf. Auch die larvale Entwicklung von D. suzukii in einem festen Medium wurde unter dem Einfluss von Azadirachtin A reduziert bzw. verhindert. Ein Einfluss des Wirkstoffes auf die Mortalit{\"a}t adulter Versuchstiere konnte nicht festgestellt werden. Die Verwendung des Pr{\"a}parates SpinTor® (Wirkstoff Spinosad) in Laborversuchen f{\"u}hrte sowohl bei adulten D. suzukii (nach 24 bis 48 h) sowie bei D. suzukii L1-Larven (nach 24 h) bei Kontakt mit einem behandelten Medium zu einer Mortalit{\"a}tsrate von 100 \%. Das Konservierungsmittel Sorbins{\"a}ure, welches als weiteres Pr{\"u}fmittel getestet wurde, zeigte bei Kontakt oder nach oraler Aufnahme keine Wirkung auf die Mortalit{\"a}t adulter D. suzukii. Die orale Aufnahme von Sorbins{\"a}ure f{\"u}hrte jedoch zu einer schwach signifikanten Reduktion der Eiablage und des Larvenschlupfes gegen{\"u}ber der Anzahl Eier und Larven der unbehandelten Kontrolle und zu einer Mortalit{\"a}tsrate von 100 \% bei L1-Larven (nach 24 h), wenn sie einem mit Sorbins{\"a}ure behandelten Medium ausgesetzt waren. Die Ergebnisse aus der vorliegenden Dissertation sollen weitere Forschungsvorhaben unterst{\"u}tzen und dazu beitragen, die Entwicklungen von Fraßk{\"o}dern bzw. K{\"o}der-Insektizid-Mischungen und K{\"o}derstationen f{\"u}r eine effiziente Attract-and-Kill Strategie zur nachhaltigen Bek{\"a}mpfung der Kirschessigfliege Drosophila suzukii zu optimieren.}, language = {de} } @phdthesis{Stollberg2024, author = {Stollberg, Maren}, title = {Vertical planting design: The suitability and microclimatic effect of perennials in a textile living wall system.}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-924}, school = {Hochschule Geisenheim University}, pages = {I -- 211}, year = {2024}, abstract = {Urban green infrastructure has gained significant attention in the context of adaptation to climate change because of its positive effects. One approach to enhancing urban green infrastructure is through the use of Living walls (LW), also known as vertical greenery systems. While considerable knowledge and studies on traditional green facades already exist, there is limited information available on LW. Both green facades and LW are associated with numerous well-documented benefits (e.g., biodiversity and clean air), but these benefits depend on the functionality and vitality of the plants. Our knowledge of plants suitable for LW is limited to only a few climate zones and empirical values that lack confirmed validity. To address this gap, we conducted a three-year experiment using a novel, modular LW system on experimental walls exposed with different exposures. The aim of the research was to develop a textile-based, substrate-free Living Wall, which displays a perennial, attractive and diverse plant image and contributes to cooling. In this experiment, we documented the development of the plants, assessed their suitability, and measured the effect of the plants on the ambient temperature. The experiment took place over three years (2017-2019) in Geisenheim, Germany, which has a temperate oceanic climate and falls under the winter hardiness Zone 8a. For the LW system, we utilized a textile-based mat without soil (1 m²) and selected plants from wet/fresh habitats to enhance evaporative cooling. We maintained frequent irrigation with a nutrient solution, resulting in the mat being consistently overwatered. Based on common designs used in landscape architecture and on the conditions of wet habitats, we created three variants: one which was seeded: "Meadow" and two plant modules: "Cascade" and "Ground Cover". Together these modules consisted of 34 perennials and geophytes. Additionally, we sowed seed mixtures of over 30 species on the textile mat (Meadow/Seeding). We also included a Control group without plants, in which moss and weeds developed and were partially removed. After a pre-growing period on horizontal greenhouse tables, we placed the green mats vertically on experimental walls facing north, south, east, and west. Four replicates of each variant were randomly installed. We assessed plant development using various methods, including visual evaluation of aesthetics and growth form, height measurements, photographs, analysis of species coverage and visibility, canopy analysis, winter survival rate, biomass measurement, root position, and leaf area. Additionally, we employed temperature sensors and an infrared (IR) camera to measure the temperature effects of the plants on and of the ambient temperature under different setups. Through the experiment, we gained valuable insights into the techniques, cultivation, and maintenance of LW. Overall, we observed differences in plant development depending on the exposure, season, plant variant, and spontaneous vegetation. The tested plants exhibited a special vertical growth form and height. We noticed delayed growth on the north exposure, with complete coverage achieved in the third year. The south exposure showed particularly high growth, while the east and west exhibited similar but slightly lower growth compared to the south. The perennials retained their visual appearance throughout the year, with almost all variants looking attractive from May to September. Until the onset of winter, all variants had an appealing appearance. Unexpectedly, we observed the establishment of moss. Most plants survived the mild winters (2018/2019), although a cold winter (2017/1018) with a late frost resulted in damage and mortality for many plants. We conducted a detailed analysis of the different plant variants, as follows: The Ground cover variant exhibited an attractive appearance and foliage decoration throughout the year. At the east, west, and north exposures, the plants showed an attractive appearance shortly after winter, while on the south wall, it took until May for the species to start regrowing. In particular, Waldsteinia ternata displayed a nice leaf texture and, together with Pachysandra terminalis, was the most visually appealing. Ajuga tenorii 'Mauro', Alchemilla caucasica, Glechoma hederacea, and Geum coccineum 'Carlskaer' demonstrated beautiful ornamental effects and flowered during the summer. The Cascade variant showcased its attractiveness during the summer season, as most of the plants became less prominent during the winter. We observed that Tellima grandiflora 'Rubra' and Heuchera Hybrid 'Purple Petticoats' were the most visually appealing in this variant. Hosta sieboldii 'Harry van Trier' exhibited a pleasing ornamental effect and flowered during the summer. The ferns exhibited delayed growth but gradually developed a nice leaf texture. Self-settled moss complemented the planting, covering the entire mat. In the Meadow / Seeding variant, we observed increasing growth in height and vegetation coverage that extended from April to October. Initially, we sowed 32 different plant species, but only 10 were able to establish and become visible. These included Galium (album and palustre), Lycopus europaeus s. str., Stachys palustris, Anthoxanthum odoratum s. str., Festuca spp., and Poa spp. It is important to follow maintenance steps for the Meadow-LW. We noticed that the vegetation recovered within a few weeks after cutting. We recommend one complete cut during the summer and the removal of dead plant material after the frost period ends in spring. To examine the temperature effects of the plants on the ambient temperature and the climatic conditions to which they were exposed, we measured the temperature in different setups. The vegetation temperature depends on factors such as air temperature, measurement position, planting variant, and plant species. We observed a cooling effect only at a short distance from the LW, indicating a microclimatic impact. In conclusion, it is possible to effectively green a textile-based, soilless LW system. However, an automated irrigation system and regular monitoring and maintenance are essential. We identified suitable perennial species for each exposure and compiled a list of plants suitable for LW, along with their specific requirements. Seeded meadow-LW can easily be established. Furthermore, we recommend continuing our methodological approaches to obtain temperature measurements in LW in future studies.}, language = {mul} } @phdthesis{Ponchon2024, author = {Ponchon, Mathilde}, title = {The entomopathogenic fungus Metarhizium robertsii and its endophytic potential in grapevine to regulate radicicole grape phylloxera populations}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim University}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-865}, school = {Hochschule Geisenheim University}, pages = {3 -- 212}, year = {2024}, abstract = {Grape phylloxera Daktulosphaira vitifoliae destroyed 30\% of the European vineyard by the end of the 19th century, attacking the woody roots of the grapevine Vitis vinifera (L.). To date, grafting grapevine on American resistant rootstocks is the leading solution to control the pest. However, grape phylloxera is present in most wine-growing soils and remains a threat in regions planted with non-grafted vines. Thus, alternative control solutions are investigated. The entomopathogenic fungus Metarhizium robertsii is known for its capacity to parasitize insects. Besides, the fungus can colonize plant rhizosphere and establish as an endophyte (i.e., within plant tissues) in many plant species. The thesis aimed to investigate if M. robertsii could persistently associate with the rhizosphere and as an endophyte in non-grafted grapevine V. vinifera without harming its growth while preventing the development of the grape phylloxera radicicole forms. Four M. robertsii strains native to four different vineyards were used and came from: i) the center-West Argentina (MsoilAR4.3), ii) the south of Australia (M224B), iii) the south-west of France (EF3.5(2)) and iv) the west of Germany (EF047). Greenhouse experiments were conducted to assess the association between M. robertsii and potted non-grafted grapevines. First, the comparison of the kinetic of grapevine rhizosphere and endosphere colonization was made, comparing the strain EF3.5(2) with a laboratory strain non-native to the vineyard (ARSEF-2575-GFP) to evaluate if a vineyard-native strain had a more durable colonization. Droplet Digital PCR (ddPCR), a culture-based method, and confocal imaging of root segments were used to characterize the associations. The strain EF3.5(2) had a higher establishment in the rhizosphere and root-endosphere of non-grafted grapevine than the strain ARSEF-2575-GFP. Both strains were established for up to 96-98 days post-inoculation (dpi) in both compartments. Then, the potential of association with the non-grafted grapevine of all four-vineyard native M. robertsii strains was compared. The rates of rhizospheric colonization at 68-70 dpi ranged from 60\% for the Argentinian MsoilAR4.3 strain, 65\% for the Australian M224B strain, 76\% for the French EF3.5(2) strain, to 100\% for the German EF047 strain. The rates of root endosphere colonization were 14\%, 10\%, 5\%, and 33\% at 68-70 dpi, respectively. No significant differences of rhizosphere and root-endosphere colonization between tested strains were recorded. Also, the fungal association unaffected the grapevine's growth and leaf pigment content during the experimental period. Finally, the effect of direct parasitism of the strain EF3.5(2) on the survival and development of radicicole grape phylloxera clone 'Pcr7' was evaluated in the woody root section bioassay. Depending on the method used to infect the insect, a significant reduction of 90 \%, 70 \%, and 86\% in survival probability was found, and 92\%, 89\%, and 93 \% in reduction of adults' development compared with control treatments. Also, the symptoms induced by grape phylloxera on non-grafted grapevines co-inoculated with M. robertsii were reduced by 91\% (mean of 4.8 ± 8.4 nodosities) compared with the phylloxera infested-plants (mean of 52.7 ± 50.7 nodosities). The qPCR analysis performed on grapevine inoculated with strain EF3.5(2) showed after 24h, the up- regulation of the VvWRKY-75, VvPR3.2, VvPR4, and VvG1, which are phylloxera-responsive defense genes involved in the resistance against phylloxera. In conclusion, M. robertsii's persistent association with non-grafted grapevine represents an alternative protection strategy against radicicole grape phylloxera, especially for wine-growing regions planted with non-grafted vines. Further field experiments should be carried out to determine the environmental factors affecting the effectiveness and persistence of M. robertsii associated with grapevine.}, language = {en} } @phdthesis{Moulis2024, author = {Moulis, Pierre}, title = {Exploration of the phenomena associated with the production of pyrrole and pyridine derivatives responsible for mousy off-flavours in wine}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-880}, school = {Hochschule Geisenheim University}, pages = {I -- 152}, year = {2024}, abstract = {In den letzten Jahren ist die Nachfrage der Verbraucher nach Bio-Lebensmitteln weiter gestiegen. Die Akteure des Weinsektors achten auf diese Erwartungen. In der Weinproduktion ist ein R{\"u}ckgang in der Anwendung bestimmter Maßnahmen, die sich direkt auf die Weinqualit{\"a}t auswirken k{\"o}nnen, zu verzeichnen. So hat beispielsweise der „M{\"a}uselton" bei Weinen mit reduziertem Sulfitgehalt zugenommen. Derzeit scheinen drei Molek{\"u}le Verursacher dieses Defekts zu sein: 2-Acetylpyrrolin (APY), 2-Acetyltetrahydropyridin (ATHP) und 2-Ethyltetrahydropyridin (ETHP). Die durchgef{\"u}hrte Forschungsarbeit, die chemische, mikrobiologische und {\"o}nologische Ans{\"a}tze kombiniert, liefert Antworten auf die Mechanismen des Auftretens dieses Fehltons im Wein. Um Antworten zu finden, wurden Methoden zur Quantifizierung der N-Heterozyklen, die f{\"u}r den „M{\"a}uselton" verantwortlich sind, mithilfe von SBSE-GC-MS-Techniken entwickelt. Die Bestimmungsmethode f{\"u}r Wein erm{\"o}glichte es, diese Substanzen in 74 verschiedenen Weinen zu quantifizieren. Die zweite Analysenmethode ist auf ein chemisch definiertes Medium abgestimmt, das alle bisher bekannten Vorstufen des „M{\"a}useltons" enth{\"a}lt. Sie erm{\"o}glicht es, Mikroorganismen unter standardisierten Bedingungen auf ihre F{\"a}higkeit zu testen, einen „M{\"a}uselton" zu erzeugen. Mit diesen Methoden konnte gezeigt werden, dass das Verh{\"a}ltnis der beiden Tautomere von 2-Acetyltetrahydropyridin nicht von den Unterschieden zwischen dem pH-Wert des Weines und der Mundh{\"o}hle beeinflusst wird. Mikroorganismen wurden aus 25 Weinen mit „M{\"a}uselton" isoliert. Die am h{\"a}ufigsten anzutreffenden Arten sind Saccharomyces cerevisiae, Oenococcus oeni oder Brettanomyces bruxellensis. Von den 353 isolierten Mikroorganismen sind nur St{\"a}mme der Arten B. bruxellensis, Lentilactobacillus hilgardii und Oenococcus oeni in der Lage, Substanzen, die einen „M{\"a}uselton" verursachen, im Modellmedium zu produzieren. Anschließend wurden St{\"a}mme aus der Sammlung, die zu diesen drei Arten geh{\"o}rten, unter denselben Bedingungen untersucht. Die Ergebnisse zeigen, dass die Konzentrationen und Verh{\"a}ltnisse der drei N-Heterozyklen signifikante Unterschiede zwischen den Arten aufweisen, dass jedoch alle untersuchten St{\"a}mme (22 St{\"a}mme von B. bruxellensis, 10 St{\"a}mme von L. hilgardii, 20 St{\"a}mme von O. oeni) die F{\"a}higkeit haben, mindestens eine der drei Komponenten zu produzieren. Weitere Versuche in Modellmedien haben gezeigt, dass es bei der Produktion m{\"a}uselnder Substanzen zu einer Interaktion zwischen Mikroorganismen kommen kann. Die Untersuchung dieser Wechselwirkungen wurde im Weinmilieu fortgesetzt. Ein Ugni blanc Most wurde mit zwei verschiedenen Saccharomyces cerevisiae St{\"a}mmen vinifiziert. Anschließend wurde die Produktion der m{\"a}uselnden Komponenten {\"u}ber 24 Tage verfolgt. Die Ergebnisse zeigten, dass unabh{\"a}ngig von den produzierenden Mikroorganismen einer der beiden S. cerevisiae St{\"a}mme zur Entwicklung von Bedingungen beitr{\"a}gt, die eine h{\"o}here APY-Produktion im Wein erm{\"o}glichen. Schließlich wurden Produktionskinetiken im Modellmedium durchgef{\"u}hrt, um festzustellen, in welchem physiologischen Stadium B. bruxellensis diese Verbindungen produzieren kann. Die Produktion von ATHP verl{\"a}uft nicht linear. Die Verbindung tritt punktuell in hohen Konzentrationen auf, insbesondere zu Beginn der station{\"a}ren Wachstumsphase, und verschwindet dann wieder. Es wurden Hypothesen {\"u}ber die physiologische Rolle dieser Verbindung aufgestellt. Schl{\"u}sselw{\"o}rter: M{\"a}uselton; Weine; Brettanomyces bruxellensis; Milchs{\"a}urebakterien; Organoleptische Abweichungen}, language = {en} } @phdthesis{Dries2024, author = {Dries, Leonie}, title = {Microbial structure and diversity in the rhizosphere of grape vines (Vitis vinifera L.)}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-827}, school = {Hochschule Geisenheim University}, pages = {II -- 133}, year = {2024}, abstract = {Microorganisms are a substantial component of the rhizosphere, and the activity and composition of rhizosphere microbial populations markedly affect interactions between plants and the soil. In addition, the microbiota of the rhizosphere can positively influence plant development, growth and vitality. In vineyards, management practices influence both grapevine root growth directly and the rhizosphere microbiota, but the exact mode of action is largely unknown. Recently, however, two new research approaches are increasingly coming into focus to enhance the grapevine growth and health: plant engineering and rhizosphere engineering (Chapter 1). In plant engineering, knowledge about plant-microbiome interactions is used for plant breeding strategies. In rhizosphere engineering, microbial communities are modified by adding specific fertilizers, nutrients, or by bio-inoculation with certain bacteria and/or fungi. Taken together, these new methods suggest a potential for reaching a more sustainable development of a pesticide- and fertilizer-reduced viticulture in the future. Consequently, the aim of this study was to investigate the bacterial rhizobiome of grapevines (Vitis vinifera L.) under different experimental designs. By characterizing the bacterial 16S rRNA gene, a statement on the existing bacterial communities and their diversity can be made and compared under different environmental conditions. For this, a method has to be established that allows to obtain rhizosphere and root material of grapevine plants, and to prepare it for sequencing and further analyses. This applies both to grapevines cultivated in greenhouses under controlled conditions as well as to variants under field conditions. The experimental designs aimed to gain knowledge regarding the bacterial diversity of the grapevine rhizosphere including different grape varieties, different grapevine rootstocks as well as different fertilization measures. The first experiment aimed to investigate the variability of the rhizosphere microbiome resulting from the genotype of the rootstock while minimizing the effect of all other environmental factors. This was made possible by investigating four ungrafted grapevine rootstock varieties of the same age, grown on the same soil under the same climatic conditions and managed identically. The bacterial communities associated with the rhizosphere of the rootstocks 1103 Paulsen, 140 Ruggeri, 161-49 Couderc, and Kober 5BB were characterized with the amplicon based sequencing technique, targeting regions V4-V5 of 16S rDNA gene. The four rootstocks showed similarities concerning the structure of the bacteria assemblage (richness and evenness). Nonetheless, differences were detected in the composition of the bacterial communities. Indeed, all investigated rootstocks recruited communities with distinguishable traits, thus confirming the role of rootstock genotype as driver of the bacteria composition (Chapter 2). In order to disentangle the effect of scion and rootstock, the rRNA (V4-V5 region of 16S rRNA) extracted from the rhizosphere of the grape varieties Riesling and Mueller-Thurgau ungrafted vs. grafted on different rootstocks were sequenced in three experimental set-ups in two different years. The bioinformatic analysis with tools designed to be robust for compositional data showed, that the investigated rootstocks or scions or combinations, respectively, recruited bacterial communities with distinguishable traits. Statistical differences were revealed between ungrafted Riesling and Mueller-Thurgau, and between grafted Riesling and ungrafted Riesling, and ungrafted Mueller-Thurgau and grafted Mueller-Thurgau. Thus, confirming the role of scion and rootstock genotype as a driver of the structure and composition of bacterial communities in the rhizosphere of grapevines (Chapter 3). In order to investigate the impact of different levels of nitrogen (N) fertilization on the rhizosphere microbiome an experimental vineyard with vines (Vitis vinifera L. cv. Pinot Noir) in large containers was examined in 2020 and 2021 at bud break. The vines were fertilized with two different levels of nitrogen added per year (N0 25 kg/ha and N1 75 kg/ha) individually. In order to examine the respective bacterial communities, rhizosphere material was sampled and a subsequent RNA-extraction followed by next generation sequencing was performed. The study revealed significant differences in the bacterial communities in the rhizosphere regarding fertilization levels and sampling depths. The results may help to understand the effect of nitrogen fertilization on the microbiome and, in the long term, reduce fertilization in viticulture, leading to more sustainable vine management (Chapter 4). Hence, superordinate, the future aim is to use new insights to enable more precise plant nutrition in the form of more accurate fertilization recommendations in order to reduce the associated costs in an economical and environmentally friendly way. A more precise knowledge of the specificity and dynamics of the grapevine rhizosphere microbiome under different management practices, grape varieties, rootstocks, and fertilization levels, should enable targeted adaptation strategies for increasingly frequent extreme years leading to a more sustainable viticulture.}, language = {en} } @phdthesis{Badura2024, author = {Badura, Jennifer}, title = {Characterization, regulation and genetic modification of the synthesis of aroma compounds in non-conventional wine yeasts}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim University}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-809}, school = {Hochschule Geisenheim University}, pages = {II -- 223}, year = {2024}, abstract = {Yeasts belonging to the genus of Hanseniaspora are widespread in nature and are generally part of the microbiome of ripe fruits, such as apples, pears and grapes. Hanseniaspora spp. form 50-75\% of the microorganisms found at the onset of grape must fermentations, H. uvarum often being the most abundant. H. uvarum is also a common isolate from other fruits, such as oranges, pineapples, mangoes, apples and pears. Since H. uvarum, known for producing high amounts of acetic acid and ethyl acetate, dominates the onset of spontaneous grape must fermentations, it greatly influences the aroma profile of wines. Besides its important role in fermentations, more biotechnological research has been reported in recent years, highlighting the universal value of H. uvarum beyond the beverage industry. In this thesis, I characterized the aroma-production profile of seven different Hanseniaspora spp. in simultaneous co-fermentations with Saccharomyces cerevisiae. Significant differences could be detected between fermentations using Hanseniaspora spp. belonging to the fast-evolving lineage (FEL) and the slow-evolving lineage (SEL). Fermentations with yeasts of FEL showed increased amounts of ethyl acetate, whereas yeasts belonging to SEL revealed no meaningful difference compared to the pure S. cerevisiae fermentation. Furthermore, co-fermentations resulted in lactic acid depletion (H. osmophila), extremely high isoamyl acetate levels (H. guilliermondii), reduction in glycerol (H. occidentalis), increased terpenols (H. opuntiae) as well as esterified terpenes (H. guilliermondii and H. uvarum). This is the first study to investigate the use of H. nectarophila and H. meyerii in relation to wine, of which fermentations using H. nectarophila revealed high levels of acetate esters. Nitrogen sources in form of amino acids have a major impact on the resulting aroma-production profile of yeasts as they serve as backbones for several volatile organic compounds. I explored amino acid uptake preferences of Hanseniaspora spp. of both lineages (H. uvarum = FEL; H. osmophila = SEL), S. cerevisiae (all glucophilic), as well as the fructophilic yeasts Starmerella bacillaris and Zygosaccharomyces rouxii in synthetic must, spiked with single amino acids. Among yeasts investigated, H. uvarum showed the most rapid amino acid uptake. Additional research on yeast fermentations with synthetic must supplemented with an amino acid mix resulted in amino acid-dependent synthesis of specific aroma compounds by the respective yeast. This study reveals similarities in both preferences in amino acid uptake and nitrogen source depending aroma compound synthesis of H. osmophila and S. cerevisiae. I investigated the transcriptomic profile of H. uvarum and S. cerevisiae to gain insight into the different regulation mechanisms involved in the synthesis of aroma compounds. Furthermore, I explored the impact of different levels of nitrogen (nitrogen deficiency/ diammonium hydrogen phosphate (DAHP) supplemented must) within the grape must on the gene expression profile and therefore on the resulting aroma profile. Even though the different nitrogen regimes did not significantly affect transcriptional levels, a major impact on both fermentation kinetics and the aroma profile could be monitored. H. uvarum unravelled possessing additional genes including alcohol acetyltransferase activity leading to a rapid esterification of higher alcohols to acetate esters. In addition, the lack of genes involved in the synthesis of higher alcohols and ethyl esters, as well as an up-regulation of genes responsible for the synthesis of acetyl-coA and acetate esters favour the high acetate ester production. In this study, I developed the first genetic modification tool for H. uvarum by constructing a synthetic marker gene encoding the hygromycin marker under the control of a H. uvarum promoter, flanked by ~1 000 bp homology region to the target locus, enabling the knock-out of one copy of the alcohol acetyltransferase 1 (ATF1) gene. By increasing the concentration of the antibiotic during selection, I could identify a knock-out of both ATF1 alleles in the diploid yeast, generating a homozygotic atf1 mutant. Fermentations resulted in a significant reduction of the acetate ester synthesis, proving the function of ATF1 as an important gene involved in the ester synthesis in H. uvarum. Genetic modification of H. uvarum was optimized by establishing a rapid PCR-based gene targeting approach for one-step gene replacement. Generation of two novel synthetic antibiotic resistance genes (pFA-hygXL and pFA-clnXL) provided resistance against hygromycin and nourseothricin, respectively. Short flanking-homology regions of 56-80 bp added to these selection markers via PCR enabled gene targeting and the deletion of both the H. uvarum LEU2 and LYS2 genes via two rounds of consecutive transformations, generating a leucine auxotrophic leu2/leu2 mutant and a lysine auxotrophic lys2/lys2 mutant, respectively. The genetic modification approach of H. uvarum using PCR-based gene targeting was further validated by targeted complementation of the auxotrophic leu2/leu2 strain.}, language = {en} } @phdthesis{Wersebeckmann2024, author = {Wersebeckmann, Vera}, title = {Terracing in steep slope viticulture and its potential to promote biodiversity in vineyard ecosystems}, volume = {2024}, edition = {1. Auflage}, publisher = {Hochschule Geisenheim}, address = {Geisenheim}, url = {http://nbn-resolving.de/urn:nbn:de:hebis:2083-760}, school = {Hochschule Geisenheim University}, pages = {212}, year = {2024}, abstract = {A substantial area of the terrestrial surface is used for agricultural production. In Europe, many farmland species and ecosystems have evolved with traditional agricultural practices and rely on extensive cultivation for their survival. Today, agrobiodiversity is threatened by the abandonment of traditional agricultural land use. The cultivation of wine is one of the oldest forms of agriculture. On steep slopes, viticulture has shaped landscapes, cultural traditions, and unique ecosystems in many regions. In Germany, steep slope viticulture has been declining dramatically in recent decades due to insufficient profitability. The abandonment of these traditional cultural landscapes threatens the cultural heritage and the flora and fauna adapted to viticultural management. One solution to halt the decline of steep slope viticulture could be a change of cultivation system from vertically oriented rows to modern terraced vineyards. Here, the rows run parallel to the hillside, facilitating cultivation, and thus reducing production costs. At the same time, a large portion of terraced vineyard consists of uncultivated embankments, which can provide valuable habitats within the agricultural system. However, little is known about the effects of a cultivation system change and vineyard abandonment on biodiversity. In addition, information on how to sustainably revegetate terrace embankments is missing. Within the framework of this dissertation, the overall aim was to evaluate the potential of terraced vineyards to promote biodiversity and investigate measures for sustainable revegetation of terrace embankments. In addition, the effects of distinct vineyard management (vertically oriented vs. terraced) and vineyard abandonment on biodiversity were assessed. The main part of this thesis is based on a field study comparing three vineyard types (vertically oriented vineyard, terraced vineyard, abandoned vineyard) that were arranged in 15 triplets along the Upper Middle Rhine Valley (UMRV) in Germany. The effects of vineyard types, local vineyard parameters, and landscape structure on biodiversity were evaluated using four species groups. Studied groups represented plants and arthropod species (grasshoppers, wild bees, spiders). In a second field study, three newly constructed terrace embankments were revegetated using different seeding techniques and seed mixtures. In addition, measures to support plant establishment were evaluated. Plant establishment was assessed for three consecutive years in permanent vegetation plots. The first study on the three vineyard types revealed that there was no uniform positive effect of one vineyard type on all investigated groups. Instead, the responses were group and taxon-specific and driven by management-related disturbance intensities, local vegetation structures, soil and landscape structure. In total, the heterogeneous landscape and small-structured vineyard agroecosystem of the UMRV supported high species diversity, hosted high numbers of rare and threatened species, and diverse species communities across vineyard types. Plant species richness was enhanced by vineyard management and particularly benefited from terraced vineyards and rather nutrient-poor and extensively managed embankments. In comparison, plant communities of fallows were completely different with lower plant diversity. Grasshoppers were supported by vineyard management, and bare ground in vineyard inter-rows supported heat- and open-adapted species. Taller vegetation stands on terrace embankments enhanced grasshopper species richness while woody structures and vineyard abandonment reduced grasshopper diversity and abundance at the local and landscape scale. Wild bee species richness and abundance were strongly determined by their nesting needs. For ground-nesting bees, the suitability of soils for nesting was important, irrespective of vineyard management types whereas above-ground nesting bees were enhanced by woody structures of fallows at the local and landscape scale. Moreover, fallows further provided valuable floral and non-floral resources for both ground- and above-ground nesting bees. For spiders, there was no difference in species richness and abundance between vineyard types but many xerophilic species adapted to open habitat structures prevailed in terraced vineyards. Vineyard fallows supported highly distinct spider communities, including some late-successional species. In conclusion, the vineyard cultural landscape of the UMRV with both actively managed and abandoned vineyards led to a high diversity of plant and arthropod communities. Hence, for its preservation, a spatially heterogeneous landscape comprising both (semi) natural and viticultural-management elements is important. Results from the second study showed that terraced vineyards and especially terrace embankments can contribute to promoting biodiversity, especially if they are revegetated with regional seed mixtures. Seeds of locally adapted populations and hydro-seeding provided higher vegetation cover which is needed to prevent severe erosion whilst non-locally adapted standard seed mixtures and manual seeding had a higher failure risk and were more prone to severe precipitation events. Taken together, vineyard terracing appears to be a win-win solution for both winegrowers and biodiversity and thus helps to maintain viticulture on steep slopes.}, language = {en} }