Analyse der Wurzelarchitektur von Gerste (<em>Hordeum vulgare</em>) unter verschiedenen Umweltbedingungen

Innerhalb der letzten Jahre zeigte der Aufruf zu einer "second green revolution" die Notwendigkeit zur Entwicklung leistungsfähiger Kulturpflanzen mit robustem Verhalten auf wechselnde Umweltbedingungen und limitierte Nährstoffangebote. Die Pflanzenwurzel spielt eine zentrale Rolle bei der Versorgung der Pflanze mit Nährstoffen und Wasser, und die Wurzelarchitektur hat demnach Einfluss auf die Entwicklung und Produktivität der Pflanze. Die Wurzelarchitektur wurde aufgrund methodischer Schwierigkeiten wenig erforscht und daher als mögliches Kriterium zur verbesserten Selektion in der Pflanzenzüchtung wenig berücksichtigt. In der vorliegenden Arbeit wurde als Teilprojekt des Verbundvorhabens „Phenomics, Transcriptomics und Genomics - ein integrierter Ansatz zur Effizienzsteigerung in der Selektion trockenstresstoleranter Gerste“ die Wurzelarchitektur von 6 deutschen Sommerbraugersten (Hordeum vulgare, L. cv. Wisa, LfL24727, Barke, Grace, Braemar, Tatum) zerstörungsfrei im Labor untersucht. Zur Erfassung der Wurzelarchitektur wurden die Gerstensamen oberflächensterilisiert und in einem transparenten Wachstumsmedium in einem axenischen System angezogen. Die Gerstenpflanzen wurden unter verschiedenen Umweltbedingungen, d. h. unter osmotischem Stress, Phosphatmangel und Nitratmangel sowie unter Kontrollbedingungen angezogen. Anschließend erfolgte auf einer speziell angefertigten, rotierenden Bildaufnahme-Plattform die digitale Bildaufnahme des Wurzelsystems der juvenilen Pflanzen nach 16 Tagen Wachstum. Dabei entstanden pro Pflanze bis zu 36 Aufnahmen des Wurzelsystems in einer vollen 360° Umdrehung. Die Digitalbilder des Wurzelsystems wurden zur Berechnung von diversen Parametern, mit welchen die Wurzelarchitektur beschrieben werden kann, verwendet. Dies erfolgte mit dem Einsatz einer dafür entwickelten Bildverarbeitungssoftware. Die Software GiA Roots wurde in Kooperation verschiedener Arbeitsgruppen von Prof. Dr. Philip Benfey, Duke University, Durham NC, USA entwickelt und ermöglicht die Berechnung von 19 verschiedenen Wurzelparametern aus Bilderserien. Pro Gerstensorte und Behandlung wurden von mindestens 10 Individuen die Wurzelarchitektur-Parameter mit GiA Roots 2D (Iyer-Pascuzzi et al., 2010; Galkovskyi et al., 2012) berechnet und anschließend statistisch ausgewertet. Die Ziele dieser Arbeit waren, neben der Etablierung der Anzuchtmethoden der Gerste im axenischen System und der Etablierung einer Hochdurchsatz Bildaufnahme- und Bildverarbeitungspipeline im Labor vor Ort, die zerstörungsfreie Untersuchung der verwendeten Gerstensorten auf phänotypische Unterschiede, um die Robustheit des Wurzelsystems bzgl. der verschiedenen Umweltbedingungen zu charakterisieren. Die Analysen ergaben, dass die Wurzelarchitektur der 6 Sommergersten statistisch signifikante Unterschiede auf einem 5% Niveau bei vielen der gemessenen Wurzelparameter aufweist. Bei Wachstum unter Kontrollbedingungen wurden zwei Wurzel-Phänotypen festgestellt, die Sorten Grace und Barke besitzen ein kleineres Wurzelsystem im Vergleich zu den Sorten Wisa, LfL24727, Braemar und Tatum. Auch zeigten sich unterschiedlich stark ausgeprägte Reaktionen der Sorten bzgl. der Stressversuche. Die Sorten Grace und Braemar zeigten eine, wie in der Literatur unter osmotischem Stress beschriebene, angepasste Veränderung ihrer Wurzelarchitektur. Die Sorten LfL24727, Grace, Braemar und Tatum zeigten außerdem ein an Phosphatmangel adaptiertes Wurzelsystem. Unter Nitratmangel wurden unterschiedlich starke, signifikante Veränderungen der Wurzelarchitektur bei jeder der getesteten Sorten beobachtet. Da die Sorten Grace und Braemar auf alle Stressversuche ein adaptiertes Verhalten des Wurzelsystems zeigten, wurden sie als robuste Sorten eingestuft. Die jeweiligen Reaktionen des juvenilen Wurzelsystems können genutzt werden, um auf bestimmte Eigenschaften der Sorten Rückschlüsse zu ziehen. Dies bietet den Pflanzenzüchtern die Möglichkeit, kombiniert mit ihren Erfahrungen über die Eigenschaften der Sorten, die hier beschriebene Methode zur Analyse der Wurzelarchitektur juveniler Gerste als zusätzliches Instrument zur Beurteilung von Sorten einzusetzen.Analysis of root system architecture (RSA) of six spring barley varieties under different environmental conditions Within the last years the call to a "second green revolution" showed the need for the development of efficient crops with robust behavior at varying environmental conditions and limited nutrient constraints. The plants’ root system plays a central role in plant nutrition and, therefore, the root architecture has influence on the development and productiveness of a plant. However, because of the methodical difficulties little attention was investigated to explore the root architecture and, hence, it was long ignored as a possible selection criterion for improved plant breeding. In the present work, the root architecture of 6 German spring barley varieties (Hordeum vulgare, L. cv. Wisa, LfL24727, Barke, Grace, Braemar and Tatum) was examined using a non-destructive approach. This was a sub project of the research project „Phenomics, Transcriptomics und Genomics - ein integrierter Ansatz zur Effizienzsteigerung in der Selektion trockenstresstoleranter Gerste“. To study the root architecture, the barley seeds were surface sterilized and grown in a transparent gellan gum under sterile conditions. Plants were grown under differential environmental conditions (osmotic stress, phosphate and nitrogen deficiency and control conditions). To obtain images of the 16-days-old roots, plants were imaged on a semi-automated rotating imaging platform. Up to 36 images per plant were captured every 10° through a full 360° rotation. Out of these images 19 root architecture parameters were calculated using GiA Roots software (Iyer-Pascuzzi et al., 2010). In cooperation with different working groups, GiA Root was developed by Prof. Dr. Philip Benfey, Duke University, Durham NC, USA. It was developed as a high-throughput image analyzing pipeline for image series and allows 19 different root architecture parameters to be considered. In this work more than 10 individuals of each barley variety and each treatment were used for image analysis followed by statistical analysis. The objectives of this work were to establish the plant culture methods and the imaging-pipeline and the analysis of the barley plants for phenotypic characteristics to evaluate the robustness of the roots under different conditions. Statistical analysis revealed that many significant differences exist at 5 per cent between the cultivars’ root parameter. Two different root phenotypes were identified grown on control medium. The varieties Barke and Grace showed a comparably small root system in contrast to the cultivars LfL24727, Grace, Braemar and Tatum. The root system responded differently to the stress treatments. The cultivars Grace and Braemar showed an adaptive reaction of the root system to osmotic stress. The cultivars LfL24727, Grace, Braemar and Tatum changed their root architecture and showed a smaller and more branched root system at the ground surface. Under nitrate deficiency all the cultivars showed distinct responses of the root system. The cultivars Grace and Braemar exhibited the most adaptive reaction and are therefore considered to be robust cultivars. The respective reactions of the juvenile root system can be used to draw conclusions on certain qualities of the cultivars. This offers the plant breeders the possibility to use this imaging system as an additional instrument for breeding selection

Regional Brain and Spinal Cord Volume Loss in Spinocerebellar Ataxia Type 3

Background: Given that new therapeutic options for spinocerebellar ataxias are on the horizon, there is a need for markers that reflect disease-related alterations, in particular, in the preataxic stage, in which clinical scales are lacking sensitivity. Objective: The objective of this study was to quantify regional brain volumes and upper cervical spinal cord areas in spinocerebellar ataxia type 3 in vivo across the entire time course of the disease. Methods: We applied a brain segmentation approach that included a lobular subsegmentation of the cerebellum to magnetic resonance images of 210 ataxic and 48 preataxic spinocerebellar ataxia type 3 mutation carriers and 63 healthy controls. In addition, cervical cord cross-sectional areas were determined at 2 levels. Results: The metrics of cervical spinal cord segments C3 and C2, medulla oblongata, pons, and pallidum, and the cerebellar anterior lobe were reduced in preataxic mutation carriers compared with controls. Those of cervical spinal cord segments C2 and C3, medulla oblongata, pons, midbrain, cerebellar lobules crus II and X, cerebellar white matter, and pallidum were reduced in ataxic compared with nonataxic carriers. Of all metrics studied, pontine volume showed the steepest decline across the disease course. It covaried with ataxia severity, CAG repeat length, and age. The multivariate model derived from this analysis explained 46.33% of the variance of pontine volume. Conclusion: Regional brain and spinal cord tissue loss in spinocerebellar ataxia type 3 starts before ataxia onset. Pontine volume appears to be the most promising imaging biomarker candidate for interventional trials that aim at slowing the progression of spinocerebellar ataxia type 3. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Evolution of disability in spinocerebellar ataxias type 1, 2, 3, and 6

International audienceObjective: The aim was to study the evolution of disability in spinocerebellar ataxias (SCAs) type 1, 2, 3, and 6 (SCA1, 2, 3, 6). Methods: We analyzed data of two longitudinal cohorts (RISCA, EUROSCA) which recruited ataxic and non-ataxic SCA1, SCA2, SCA3, and SCA6 mutation carriers. To study disability, we used a five-stage system for ataxia defined by walking ability (stages 0-3) and death (stage 4). Transitions were analyzed using a multi-state model with proportional transition hazards. Based on the hazard estimates, transition probabilities and the expected lengths of stay in each stage were calculated. We further studied the effect of sex and CAG repeat length on progression. Results: Data of 3138 visits in 677 participants were analyzed. Median SARA scores for SCA1, SCA2, SCA3, and SCA6 ranged from 1.5 (interquartile range [IQR] = 0.0-3.5) to 3.5 (IQR = 1.4-6.1) in stage 0, 11.5 (IQR = 9.6-14.0) to 13.8 (IQR = 11.0-16.0) in stage 1, 19.0 (IQR = 17.0-21.0) to 23.8 (IQR = 19.5-27.0) in stage 2, and 28.5 (IQR = 26.0-32.5) to 34.0 (IQR = 32.6-37.1) in stage 3. Modeling allowed to calculate the subtype-specific probability to be in a certain stage at a given age and duration of each stage. CAG repeat length was associated with faster progression in SCA1 (HR, 95% CI: 1.1, 1.1-1.2), SCA2 (1.2, 1.1-1.3), and SCA3 (1.1, 1.0-1.2). In SCA6, female sex was associated with faster progression (1.7, 1.1-2.6). Interpretation: Our data are important for counselling of patients, assessment of the relevance of outcome markers, and design of clinical trials

Evolution of Clinical Outcome Measures and Biomarkers in Sporadic Adult-Onset Degenerative Ataxia

BackgroundSporadic adult-onset ataxias without known genetic or acquired cause are subdivided into multiple system atrophy of cerebellar type (MSA-C) and sporadic adult-onset ataxia of unknown etiology (SAOA). ObjectivesTo study the differential evolution of both conditions including plasma neurofilament light chain (NfL) levels and magnetic resonance imaging (MRI) markers. MethodsSPORTAX is a prospective registry of sporadic ataxia patients with an onset >40 years. Scale for the Assessment and Rating of Ataxia was the primary outcome measure. In subgroups, blood samples were taken and MRIs performed. Plasma NfL was measured via a single molecule assay. Regional brain volumes were automatically measured. To assess signal changes, we defined the pons and middle cerebellar peduncle abnormality score (PMAS). Using mixed-effects models, we analyzed changes on a time scale starting with ataxia onset. ResultsOf 404 patients without genetic diagnosis, 130 met criteria of probable MSA-C at baseline and 26 during follow-up suggesting clinical conversion to MSA-C. The remaining 248 were classified as SAOA. At baseline, NfL, cerebellar white matter (CWM) and pons volume, and PMAS separated MSA-C from SAOA. NfL decreased in MSA-C and did not change in SAOA. CWM and pons volume decreased faster, whereas PMAS increased faster in MSA-C. In MSA-C, pons volume had highest sensitivity to change, and PMAS was a predictor of faster progression. Fulfillment of possible MSA criteria, NfL and PMAS were risk factors, CWM and pons volume protective factors for conversion to MSA-C. ConclusionsThis study provides detailed information on differential evolution and prognostic relevance of biomarkers in MSA-C and SAOA. (c) 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Stage-dependent biomarker changes in spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3) is the most common autosomal dominant ataxia. In view of the development of targeted therapies, knowledge of early biomarker changes is needed. We analyzed cross-sectional data of 292 SCA3 mutation carriers. Blood concentrations of mutant ATXN3 were high before and after ataxia onset, while neurofilament light deviated from normal 13.3 years before onset. Pons and cerebellar white matter volumes decreased and deviated from normal 2.2 years and 0.6 years before ataxia onset. We propose a staging model of SCA3 that includes a biomarker stage characterized by objective indicators of neurodegeneration before ataxia onset