Preface

One of the current challenges in plant biology is the development of quantitative phenotyping approaches to link the genotype and the environment to plant structural, functional, and yield characteristics in order to meet the growing demands for sustainable food, feed, and fuel. The genotype of a plant consists of all of the hereditary information within the individual, whilst the phenotype, which represents the morphological, physiological, anatomical, and developmental characteristics, is the result of the interaction between the genotype and the environment. Understanding this interaction is one of the major challenges in plant sciences. In plant breeding, the ultimate goal is the improvement of traits of agricultural importance related to disease resistance, high yields, and the plant’s ability to grow in unfavourable environmental conditions. Currently, breeding approaches produce an annual yield increase of approximately 1% for major crops, which is below the over 2% increase needed to meet the global demands for food by 2050 (Ray et al., 2013).Rapid developments in plant molecular biology and in molecular-based breeding techniques have resulted in an increasing number of species being sequenced and large collections of mutants, accessions, and recombinant lines allowing detailed analysis of gene functions. High-definition genotyping can now be carried out on thousands of plants in an automated way at continuously decreasing costs, thereby facilitating association genetics and the determination of multi-parental quantitative trait loci (QTLs) (Poland and Rife, 2012). For transcriptomic, proteomic, and metabolomic analyses large, often robotized, platforms are available allowing detailed characterization of the biochemical status of plants at a reasonable cost (Ehrhardt and Frommer, 2012). By contrast, an understanding of the link between genotype and phenotype has progressed more slowly and is the major limiting step i

Host pathogen interactions in relation to management of light leaf spot disease (caused by Pyrenopeziza brassicae) on Brassica species

Light leaf spot, caused by Pyrenopeziza brassicae, is currently the most damaging disease problem in oilseed rape in the UK. According to recent survey data, the severity of epidemics has increased progressively across the UK, with current yield losses of up to £160M per annum in England and more severe epidemics in Scotland. Light leaf spot is a polycyclic disease with primary inoculum consisting of air-borne ascospores produced on diseased debris from the previous cropping season. Splash-dispersed conidia produced on diseased leaves are the main component of the secondary inoculum. P. brassicae is also able to infect and cause considerable yield losses on vegetable brassicas, especially Brussels sprouts. There may be spread of light leaf spot among different brassica species. Since they have a wide host range, Pyrenopeziza brassicae populations are likely to have considerable genetic diversity and there is evidence suggesting population variations between different regions, which need further study. Available disease-management tools are not sufficient to provide adequate control of the disease. There is a need to identify new sources of resistance, which can be integrated with fungicide applications to achieve sustainable management of light leaf spot. Several major resistance genes and quantitative trait loci have been identified in previous studies, but rapid improvements in the understanding of molecular mechanisms underpinning B. napus – P. brassicae interactions can be expected through exploitation of novel genetic and genomic information for brassicas and extracellular fungal pathogens.Peer reviewe

Primary Postnatal Dorsal Root Ganglion Culture from Conventionally Slaughtered Calves

Neurological disorders in ruminants have an important impact on veterinary health, but very few host-specific in vitro models have been established to study diseases affecting the nervous system. Here we describe a primary neuronal dorsal root ganglia (DRG) culture derived from calves after being conventionally slaughtered for food consumption. The study focuses on the in vitro characterization of bovine DRG cell populations by immunofluorescence analysis. The effects of various growth factors on neuron viability, neurite outgrowth and arborisation were evaluated by morphological analysis. Bovine DRG neurons are able to survive for more than 4 weeks in culture. GF supplementation is not required for neuronal survival and neurite outgrowth. However, exogenously added growth factors promote neurite outgrowth. DRG cultures from regularly slaughtered calves represent a promising and sustainable host specific model for the investigation of pain and neurological diseases in bovines

Root morphology and seed and leaf ionomic traits in a Brassica napus L. diversity panel show wide phenotypic variation and are characteristic of crop habit

Background: Mineral nutrient uptake and utilisation by plants are controlled by many traits relating to root morphology, ion transport, sequestration and translocation. The aims of this study were to determine the phenotypic diversity in root morphology and leaf and seed mineral composition of a polyploid crop species, Brassica napus L., and how these traits relate to crop habit. Traits were quantified in a diversity panel of up to 387 genotypes: 163 winter, 127 spring, and seven semiwinter oilseed rape (OSR) habits, 35 swede, 15 winter fodder, and 40 exotic/unspecified habits. Root traits of 14 d old seedlings were measured in a ‘pouch and wick’ system (n = ~24 replicates per genotype). The mineral composition of 3–6 rosette-stage leaves, and mature seeds, was determined on compost-grown plants from a designed experiment (n = 5) by inductively coupled plasma-mass spectrometry (ICP-MS). Results: Seed size explained a large proportion of the variation in root length. Winter OSR and fodder habits had longer primary and lateral roots than spring OSR habits, with generally lower mineral concentrations. A comparison of the ratios of elements in leaf and seed parts revealed differences in translocation processes between crop habits, including those likely to be associated with crop-selection for OSR seeds with lower sulphur-containing glucosinolates. Combining root, leaf and seed traits in a discriminant analysis provided the most accurate characterisation of crop habit, illustrating the interdependence of plant tissues. Conclusions: High-throughput morphological and composition phenotyping reveals complex interrelationships between mineral acquisition and accumulation linked to genetic control within and between crop types (habits) in B. napus. Despite its recent genetic ancestry (<10 ky), root morphology, and leaf and seed composition traits could potentially be used in crop improvement, if suitable markers can be identified and if these correspond with suitable agronomy and quality traits

Züchtung für den Klimawandel : Genetik und Physiologie von Samenkeimung, Keimlingswachstum und früher Trockenresistenz in Winterraps (Brassica napus L.)

In the face of climate change, it seems crucial to increase crop resistance in terms of improved vigor and stress adaptability. To achieve this aim, new screening tools must be developed which allow a reliable selection for beneficial trait or gene combinations contributing to enhanced seed vigor and stable seedling development. A major aim of the present work was the identification of physiological, anatomic and genetic markers associated with improved seed germination and stable seedling development under optimal and suboptimal water conditions in rapeseed.A considerable potential for the improvement of seed vigor could be demonstrated within a genomics screening approach, in which several quantitative trait loci (QTL) could be identified throughout the rapeseed genome underlying seed germination and early seedling growth. Promising candidate genes for seed germination and seedling growth were found in co-localization with the identified QTL, such as Bna.SCO1, Bna.ATE1 and Bna.ARR4. Genomic SNP markers were identified which are anchored in the genomic regions associated with seed vigor. These markers are now available for genomics-based selection for improved seed vigor. Within two independent physiological experiments, osmotic stress responses of rapeseed genotypes differing in their drought resistance were investigated with regard to the seedling shoot and root. For a controlled application of osmotic stress, a novel hydroponic cultivation system was developed. In response to the osmotic stress treatment genotypes reacted with a shift in their shoot metabolite and hormone patterns. An accumulation of osmotically active compounds, such as proline or sugars, suggest that osmotic adjustment is an important factor in the adaptation of rapeseed to drought. However, osmotic adjustment was more distinct in homozygous lines than in hybrids, while the latter showed better growth performance under osmotic stress. It is therefore assumed that enhanced drought compatibility can be at least partially, and possibly mainly attributed to heterosis. For the characterization of root responses to osmotic stress, a new phenotyping tool was established, basing on the principles of Sholl analysis , a neuroscientific method applied for neural network analysis. The results showed that Sholl analysis captures interactive root properties which are normally not captured by conventional root phenotyping software. Under osmotic stress, rapeseed seedlings reacted with altered root architecture, due to enhanced lateral root growth at the expense of the number of lateral roots. A stronger reaction was observed in the resistant genotype. This suggests that the observed changes in root architecture contribute to a better water acquisition during soil desiccation in the field.Im Zuge des Klimawandels beeinträchtigen immer häufiger auftretende Temperatur- und Niederschlagsextrema die Stabilität von Nutzpflanzenerträgen. Vor diesem Hintergrund ist es notwendig, agronomische Merkmale zu verbessern, die zu einer Steigerung und Stabilisierung von Erträgen unter variierenden Umweltbedingungen beitragen. Vorangehende Arbeiten haben gezeigt, dass das Ertragspotential von Kulturpflanzen bereits zum Zeitpunkt der Keimung und des Keimlingswachstums konstituiert wird. Ziel der vorliegenden Arbeit war es daher, physiologische und architektonische Merkmale, sowie genetische Marker zu identifizieren, die eine Selektion auf verbesserte Keimung und Keimlingstriebkraft in Winterraps (Brassica napus) ermöglichen. In einer genomweiten Assoziationsstudie konnten verschiedene Genomregionen eingegrenzt werden, welche das Keimverhalten von Winterraps signifikant beeinflussen. Innerhalb dieser Regionen liegen einige vielversprechende Kandidatengene, welche bereits ausführlich im Zusammenhang mit Keimung und Keimlingswachstum in Arabidopsis thaliana diskutiert wurden. Mit den Ergebnissen der Assoziationsstudie stehen weiterhin co-segregierende genetische Marker zur Verfügung, welche zur Selektion auf verbesserte Keimung in Winterraps verwendet werden können. In zwei unabhängigen physiologischen Experimenten wurde der Einfluss von osmotischem Stress auf das Wachstum von Spross und Wurzel von Winterraps-Keimlingen untersucht. Zur dosierten Applikation von osmotischem Stress in Nährlösung wurde ein geeignetes in vitro-Kultivierungssystem entwickelt. Unter osmotischem Stress reagierten Winterraps-Keimlinge mit einer Anreicherung von osmotisch wirksamen Metaboliten. Beim Vergleich homozygoter und heterozygoter Genotypen zeigten sich deutliche Unterschiede im Pflanzenwachstum und in der Anreicherung bestimmter Metaboliten. Während Linien mit einer stärkeren Akkumulation von Osmolyten im Spross reagierten, jedoch nicht in der Lage waren, das Sprosswachstum unter Stressbedingungen aufrecht zu erhalten, wurde das Sprosswachstum in Hybridgenotypen trotz einer nur moderaten Reaktion in den Metabolitenmustern nicht durch osmotischen Stress beeinträchtigt. Dies lässt vermuten, dass der Heterosiseffekt maßgeblich zu einer verbesserten Trockenverträglichkeit in Winterraps beiträgt. Der Einfluss von osmotischem Stress auf das Wurzelwachstum wurde mithilfe der Sholl-Methode , eines Verfahrens aus der Neurobiologie, charakterisiert. Angewandt auf das Wurzelsystem ermöglicht diese Methode eine globale Erfassung der Wurzelarchitektur. Unter osmotischem Stress reagierten Rapskeimlinge mit einer ähnlichen Veränderung ihrer Wurzelarchitektur, hauptsächlich verursacht durch eine verminderte Neubildung von Lateralwurzeln und ein gesteigertes Wachstum vorhandener Lateralwurzeln. Im Vergleich eines trockenresistenten und eines empfindlichen Genotypen zeigte sich, dass eine ausgeprägtere Wurzelplastizität mit einer Trockenresistenz von Winterraps im Keimlingsstadium einhergeht

Entwicklung salzresistenter Maishybriden : Ein Lösungsansatz zur Überwindung des globalen Problems der Bodenversalzung

Bodenversalzung stellt für die pflanzenbauliche Nutzung weltweit ein großes Problem dar. Vor allem in ariden Gebieten, in denen die Verdunstung gegenüber dem Niederschlag überwiegt, führt eine mangelnde Auswaschungvon Salzen zur Beeinträchtigung der Bodenfruchtbarkeit und -nutzbarkeit. Mit konventionellen Züchtungsmethoden gelang es dem Institut für Pflanzenernährung salzresistente Maishybriden zu entwickeln, die auch auf versalztem Kulturland eine gute Ertragsbildung aufweisen. Grundlage hierfür war ein besseres physiologisches Verständnis der begrenzenden Wachstumsprozesse in den Pflanzen