Development of root phenotyping methods and QTL analysis of root traits in grapevine mapping populations

Facing climatic change and upcoming extreme weather events require the adaptation of agricultural crops to conditions like extended drought periods in the future. Therefore, the incorporation of promising morphological and physiological qualities is necessary in crop breeding strategies. Regarding heat and drought, plant roots play an essential role for adequate water uptake and efficient exploitation of water resources in the soils. As plant roots are crucial for crop performance and yield, investigation of phenotypic root traits is a promising approach to promote breeding efforts. However, phenotyping of root systems has proven to be extremely challenging due to their hidden nature. In this study, grapevine adventitious root development from grapevine woody cuttings was investigated by three different phenotyping methods to identify QTL regions linked to grapevine adventitious root formation and root system characteristics. The first attempt of classifying early adventitious root formation on woody cuttings grown in perlite substrate resulted in the identification of four QTLs. To further investigate sub-traits of root formation, image-based analysis was envisaged. Therefore, a root phenotyping system based on rhizotrons suitable for high throughput root architecture screenings of mapping populations was developed and evaluated. The utilization of rhizotrons for root phenotyping provided a data rich basis for QTL mapping of two mapping populations and revealed 18 QTLs in total for root related traits and four QTLs for leaf area. Thirdly, certain genotypes of a grapevine mapping population grown in the field were analysed regarding root system characteristics resulting in four identified QTLs in total; three QTLs associated with root system characteristics and one QTL associated with shoot biomass. Finally, the three root system phenotyping methods were compared regarding their performance by examining the individual throughput potential, time and cost effort, number of measurable traits, as well as number and quality of resulting QTL regions. This study describes the development and analysis of phenotyping methods for grapevine root systems. It contributes to the identification of potential genomic regions and candidate genes involved in the regulation of adventitious root formation providing new insights relevant for breeding purposes and breeding research of grapevine rootstocks.Der Klimawandel und zukünftig vermehrt auftretende Extremwetterereignisse erfordern die Anpassung landwirtschaftlicher Nutzpflanzen an besondere klimatische Bedingungen wie anhaltende Dürreperioden. Daher müssen entsprechende morphologische und physiologische Eigenschaften in der modernen Pflanzenzüchtung berücksichtigt werden. Besonders die Entwicklung des Wurzelsystems ist entscheidend für Leistung und Ertrag der Nutzpflanzen. Im Hinblick auf Hitze und Trockenheit spielen die Wurzeln eine essenzielle Rolle für eine ausreichende Wasseraufnahme und effektive Verwertung der Wasserressourcen im Boden. Die phänotypische Untersuchung von Wurzeleigenschaften ist daher eine vielversprechende Strategie in der Pflanzenzüchtung, jedoch mit besonderen Schwierigkeiten verbunden, da Wurzeln unterirdisch wachsen und im Boden nur schwer zugänglich sind. In dieser Arbeit wurde die Entwicklung von Adventivwurzeln an Rebenstecklingen mit Hilfe drei verschiedener Phänotypisierungsmethoden untersucht, um QTL Regionen zu identifizieren, die assoziiert sind mit der Entstehung von Rebenwurzeln und verschiedenen Eigenschaften ihrer Wurzelsysteme. Zunächst wurden Holzstecklinge in Perlitsubstrat angezogen, um die Entstehung der Adventivwurzeln zu klassifizieren und die phänotypischen Daten zur QTL-Berechnung zu verwenden. Um die Merkmale der Wurzeln mit Hilfe von Bildanalyseverfahren genauer zu erfassen, wurde ein Phänotypisierungssystem basierend auf Rhizotronen entwickelt und evaluiert, das für die Anwendung von Hochdurchsatz-Screenings ganzer Kreuzungspopulationen geeignet war. Insgesamt wurden die Wurzeln von zwei Kreuzungspopulationen phänotypisiert und die folgende QTL-Berechnung ergab insgesamt 18 QTLs für Wurzelmerkmale und vier QTLs für die Blattfläche. In einem weiteren Feldversuch wurden ausgesuchte Genotypen der bereits getesteten Kreuzungspopulation bezüglich ihrer Wurzeleigenschaften untersucht. Durch diesen Feldversuch konnten vier QTLs identifiziert werden, davon waren drei assoziiert mit Wurzeleigenschaften und ein QTL assoziiert mit der Biomasse des Sprosses. Schließlich wurden alle drei Methoden zur Wurzelphänotypisierung an Reben bezüglich ihres Durchsatzes, des Kosten- und Zeitaufwands, der Anzahl und Qualität messbarer Wurzelmerkmale sowie der Anzahl gefundener QTL-Regionen verglichen. Die vorliegende Studie beschreibt die Entwicklung und Analyse der drei Phänotypisierungs-methoden an Rebenwurzeln. Sie liefert somit einen wichtigen Beitrag zur Identifikation von QTLs und potenziellen Kandidatengenen im Zusammenhang mit Wurzelwachstum und seiner Regulierung. Die so gewonnenen neuen Erkenntnisse tragen zum Fortschritt in der Züchtung und Züchtungsforschung an Rebenunterlagen bei

High-resolution 3D phenotyping of the grapevine root system using X-ray Computed Tomography

Plant roots are essential for water and nutrient uptake and contribute to the plants' response to environmental stress factors. As the hidden half of a plant, investigation of root systems is highly challenging, most of available methods are destructive and very labour-intensive. In this proof-of-concept study, a non-invasive X-ray micro computed tomography (X-ray µCT) method was applied to investigate the phenotypic variation of the complex three-dimensional (3D) architecture of grapevine roots as a function of genotype and soil. Woody cuttings of 'Calardis Musqué', 'Villard Blanc' and V3125 ('Schiava Grossa' x 'Riesling') were cultivated in polypropylene columns filled with two different soil types, clay loam and sandy loam, for 6 weeks. Afterwards, the columns were scanned once using the technique of X-ray µCT. The received raw data were analysed for the reconstruction of 3D root system models (3D model), which display a non-destructive visualization of whole, intact root systems with a spatial resolution of 42 µm. The 3D models of all investigated plants (in total 18) were applied to quantify root system characteristics precisely by measuring adventitious root length, lateral root length, total root length, root system surface area, root system volume and root growth angles from the woody cutting relative to a horizontal axis. The results showed that: (i) early root formation and root growth differed between genotypes, especially between 'Calardis Musqué' and 'Villard Blanc'; and (ii) the soil type does influence adventitious root formation of V3125, but had minor effects on 'Calardis Musqué' and 'Villard Blanc'. In conclusion, this innovative, high-resolution method of X-ray µCT is suitable for high resolution phenotyping of root formation, architecture, and rooting characteristics of grapevine woody cuttings in a non-destructive manner, e.g. to investigate root response to drought stress and would provide new insights into phylloxera root infection

Gendering marteloscopes: digitalization of gender-knowledge in STEM

Mit Gendering Marteloskope stellen wir Entwicklungsprozess dar: Entstanden ist videografisches Material in Marteloskopen, die im Wald Bäume, Tablets und Menschen in Dialog zueinander setzen. Die Videografie und die Erfahrungen vor Ort werden mit Ansätzen aus Gender in Science and Technlogy Studies reflektiert sowie mit digital unterstützter kollaborativer Didaktik über interaktive Webdokumentationen zu Open Science Modulen zusammengeführt

Promoting Well-Being in Students Through an Art-of-Living Intervention: Developing an Online Training for Eighth and Ninth Graders

During secondary school, students’ well-being is challenged in manifold ways and declines continuously. To address this issue, we designed and evaluated a six-day online art-of-living intervention to foster eighth and ninth graders’ (N = 69) well-being. Art-of-living (AoL) is based on empirical evidence and conceptualizes strategies that lead to well-being. We tested the effectiveness of the AoL training and investigated the possible contribution of body-related AoL exercises to cognitive exercises by comparing two intervention groups (cognitive training vs. cognitive and body-focused training) and a waitlist control group. Levels of AoL and well-being at pretest, posttest, and two-week follow-up showed that both significantly increased in the intervention groups. No significant differences were found between the cognitive and combined training. We discuss methodological issues of the study and propose that the approach to enhance student well-being by using art-of-living exercises is fruitful for application in school and should be explored further

Tunable Magnetic Phases at Fe3O4/SrTiO3\mathrm{Fe_{3}O_{4}/SrTiO_{3}} Oxide Interfaces

We demonstrate the emergence and control of magnetic phases between magnetite (Fe$_3$O$_4$), a ferrimagnetic halfmetal, and SrTiO$_3$, a transparent nonmagnetic insulator considered the bedrock of oxide-based electronics. The Verwey transition (T$_V$) was detected to persist from bulk-like down to ultrathin Fe$_3$O$_4$ films, decreasing from 117 ± 4 K (38 nm) to 25 ± 4 K (2 nm), respectively. Element-selective electronic and magnetic properties of the ultrathin films and buried interfaces are studied by angle-dependent hard X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism techniques. We observe a reduction of Fe$^{2+}$ ions with decreasing film thickness, accompanied by an increase of Fe$^{3+}$ ions in both tetrahedral and octahedral sites and conclude on the formation of a magnetically active ferrimagnetic 2 u.c. γ-Fe$_2$O$_3$ intralayer. To manipulate the interfacial magnetic phase, a postannealing process causes the controlled reduction of the γ-Fe$_2$O$_3$ that finally leads to stoichiometric and ferrimagnetic Fe$_3$O$_4$/SrTiO$_3$(001) heterointerfaces

Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum

The global ocean’s oxygen inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We report new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analog to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM