Browsing by Subject "Vielfalt"

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Diversity in the tropical multipurpose shrub legumes Cratylia argentea (Desv.) O. Kuntze and Flemingia macrophylla (Willd.) Merrill.
(2006) Andersson, Meike S.; Schultze-Kraft, Rainer
Cratylia argentea (Desv.) O. Kuntze and Flemingia macrophylla (Willd.) Merrill are promising tropical multipurpose shrub legumes. Both are drought-tolerant, well adapted to low-fertility, acid soils, and especially suited for low-input smallholder production systems in the sub-humid and humid tropics. They can be used e.g. as dry season forage supplementation, live soil cover or mulch, erosion barrier hedges, and shade-providing shrubs in young coffee and cocoa plantations. Germplasm collections were assembled from the wild-legume flora in Brazil (C. argentea) and Southeast Asia (F. macrophylla), but research and development are so far based on only a few accessions. Knowledge about the extent of genetic diversity within these collections is very limited. In addition, the potential utilization of F. macrophylla is so far limited by poor forage quality and acceptability of the few evaluated accessions. The objective of the present study, conducted in a research cooperation with the International Centre for Tropical Agriculture (CIAT), Cali, Colombia, was to assess the diversity in the germplasm collections of C. argentea (38 accessions) and F. macrophylla (69 accessions) in terms of morphological and phenological traits, agronomic and forage quality traits, and molecular markers, and to identify superior genotyes. Based on these different characterization approaches, the objective was furthermore to establish core collections for F. macrophylla, and to compare and validate the different strategies, giving particular consideration to their practical implications (time and cost efficiency) for the application to small collections of perennial wild tropical legumes. Cratylia argentea High diversity in terms of phenological and agronomic as well as forage quality traits was detected in the collection, with scope for plant improvement in terms of higher dry season DM production. Accessions CIAT 18674 and 22406 were identified as promising for further evaluation since they were similar to the commercial cultivar "Veraniega" in terms of forage quality, and superior in terms of DM production, particularly in the dry season. Molecular marker analysis with RAPDs showed that the genetic diversity in the collection was relatively low and fairly homogeneously distributed. Accessions CIAT 22373, 22378, 22380, 22381 and 22411 were identified as possible duplicates. Flemingia macrophylla High diversity in terms of morphological and agronomic as well as forage quality traits was detected among the 69 accessions. The identification of four morphotypes in the collection probably has taxonomic implications. Scope for plant improvement was identified with respect to forage quality - one of the species´ main limitations. Accessions CIAT 18437, 21083 and 21090 had similar DM production and higher digestibility than the control accession, and were virtually free of extractable condensed tannins. Problems with low palatability and low seed production of these promising accessions need to be further studied. Genetic diversity in F. macrophylla was higher than in C. argentea, and corresponded closely to the four morphotypes revealed by conventional characterization. Various duplicate accessions were identified, and evidence was provided that the non-Asian accessions are not native to their collection site regions, but rather introduced from Southeast Asia. The results have direct applications for plant improvement of these promising multipurpose legumes. The superior genotypes selected in this study will be used in work with farmers in CIAT-research sites in Central America and distributed to partners. It must be recognized, however, that the diversity assessed is influenced by the climatic and edaphic conditions at the site where the studies were conducted. Therefore, multilocational trials should be considered with a selected subset (including the promising accessions) of C. argentea and F. macrophylla i) to assess the extent of genotype x environment interaction, and ii) to identify genotypes with consistently high performance in a range of distinct environments. Research on the reproduction system of both species is urgently required to determine the potential extent and impact of outcrossing. Beyond the immediate application of these species for farmer utilization, the results of the use and comparison of different approaches to assess diversity and to establish core collections can help to improve germplasm management and characterization of wild tropical legume species in general. Random sampling has been identified as a valuable and resource-efficient strategy for the creation of core collections when no additional information about accessions is available, and in the absence of adequate funds. The validation of the findings of this study with a broader range of perennial tropical wild legumes is necessary to assess their applicability to other species.
Mitochondrial haplotypes, gene expression and nuclear diversity in two strains of laying hens
(2021) Dreyling, Clara; Hasselmann, Martin
The domesticated chicken (Gallus gallus domesticus) is the most popular and widely spread domestic fowl worldwide, providing human with a stable source of protein in form of meat and eggs for centuries. The ongoing growth of human population increases the need for food and made poultry production one of the fasted growing sectors in the past decades. This need for food has resulted in several different strains which outperform their wild ancestors in terms of meat and egg production. During the past decades not only animal welfare gained importance but also ecological aspects such as global warming and the shortage of resources are becoming more important to society. One important resource for mankind which is becoming shortened is phosphorus (P), whose deposits in form of rock phosphate could be exhausted within the next 50-100 years. 90% of P supply is used in agriculture as fertilizer, whose demand will increase as well with growing population. This thesis focuses on the mitochondrial genetic background and mitochondrial related gene expression in the context of the productive life span and different diets in two contrasting high-yielding strains of laying hens, Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL). Mitochondria, which are commonly known as the powerhouse of the cell due to their role as the main producer of energy, play roles in other processes from cellular homeostasis to the process of ageing. The process of oxidative phosphorylation depends on the availability of P and thus, they become an important part of the complex framework of P utilization. In addition, mitochondrial haplotypes are known to affect physiological traits such as body weight in laying hens or important traits such as e.g. the metabolic capacity in dairy cows. It is known, that single mutations in the mitochondrial genome lead to a better adaptation to height in the Tibetan chicken or play a role in diseases from Alzheimer to obesity or lead to resistance to disease such as Marek’s disease in birds. This work provides insight into the whole mitochondrial genome of 180 laying hens of two commercial strains and links this information to physiological traits and genetic diversity. In addition, the first large-scaled gene expression analyses in the context of the productive life span and different P and Ca contents in laying hens is implemented. The analysis of mitochondrial haplotypes revealed a low level of genetic diversity with only three haplotypes within the LB strain while all LSL hens shared the same mitochondrial genome. Following from this observation, the nuclear genome was analysed based on genotyping data to reveal the whole genetic diversity of both strains. On the nuclear genetic level, both strains appeared as clearly distinct and equally diverse, while some individuals appear as strikingly close related. These individuals are mostly half-siblings sharing the same mitochondrial haplotype, underlining the need for more analyses about the genetic structure about the parental generation, especially the maternal background. Although there were no strong associations were found between the mitochondrial haplotypes and the analysed phenotypic traits (feed intake, body weight, P and Ca utilization), the differences between the strains indicate a potential involvement of the mitochondrial genetic background. The gene expression analyses revealed tissue type and point of the productive life span as the main influencers on gene expression while the influence of the strain is secondary. In addition, the expression of the gene GAPDH, which is frequently used as a reference gene for normalization in gene expression studies, was influenced by tissue and strain, leading to the decision to exclude it as a reference, that should be considered for in further studies. Further, no influence of the changes in dietary P and Ca on gene expression could be observed, suggesting that a reduction of 20% of both minerals is possible without the need to adapt gene expression. However, the results show, that a reduction of both minerals has less effect than a reduction of P alone, leading to an imbalance. In the context of the productive live span, mitochondrial and mitochondrial regulatory genes react contrary, illustrating the complexity of mitochondrial gene expression and regulation. In addition to the higher variance in the analysed phenotypic traits and mitochondrial genome in LB hens, they showed signs of increased oxidative stress compared to LSL hens. In the context of the productive life span, a potential higher demand for energy is suggested, since OXPHOS related gene expression is increasing. As a conclusion this work provides an insight into the mitochondrial genome and provides the first large scaled analysis of mitochondrial linked gene expression in two contrasting laying hen strains.
Molecular and phenotypic diversity in populations of Fusarium culmorum on cereal hosts
(2022) Castiblanco Vargas, Eveline Valheria; Miedaner, Thomas
Fusarium head blight is one of the most devastating diseases of cereals globally and responsible for large harvest losses, not only due to the reduction in productivity but also due to the contamination of the grain with mycotoxins. The major causal agent worldwide is Fusarium graminearum; in Europe also other Fusarium species, among them Fusarium culmorum (FC) play an important role. The interaction between Fusarium species and cereals has been categorized as quantitative according to previous phenotypic and genetic observations. We studied the molecular and phenotypic diversity of natural populations of FC and how they interact with four cereals (bread wheat, durum wheat, triticale, rye) as host. Specifically, we sought (i) to understand the interaction between host and isolate, and between isolate and environment using the variance partition approach offered by mixed models applied to analyze multi-environmental studies; (ii) to identify or validate the association of Fusarium genes previously assigned as candidates using field aggressiveness and deoxynivalenol (DON) production; and (iii) to compare the application and results of the candidate gene association mapping approach applied to the same population of FC isolates but with different phenotypic data obtained from inoculation in different hosts-bread wheat and rye. Phenotyping was based on multi-environmental field experiments where each plot of the host plant was artificially inoculated with spores of the respective isolate in accordance with the experimental design. Aggressiveness was visually quantified as the percentage of spikelets with symptoms per plot and was repeatedly evaluated over time. The content of the mycotoxin deoxynivalenol (DON) in the harvested grain was evaluated by double enzyme linked immunosorbent assays (ELISA). Genes previously reported in the literature as related to aggressiveness were selected for sequencing. Using the available F. graminearum genome sequence, specific primers were constructed to amplify and sequence the most variable regions of the respective genes. The partitioning of the phenotypic variance using mixed models, for a subpopulation of 38 FC isolates in four cereal hosts, allowed to disaggregate the magnitude of the genotypic and environmental variance, and the environmental variance in turn into its different components. The genotypic variance was significant, but was exceeded by the magnitude of the environmental variance and its interactions with genotype, showing that the role of plasticity in the pathosystem of Fusarium culmorum and its cereal hosts is highly important. In contrast, the variance associated with the host factor and the interactions with host were not significant, confirmed by high values of genetic correlation amogn host. This result supports the categorization of the cereal/Fusarium culmorum interaction as unspecific and quantitatively inherited also from the view of the pathogen. For the present study, plasticity was understood as the changes in the phenotype of the pathogen that could be attributed to changes induced by the environment. Our data revealed the year as factor with the highest influence on plasticity, meaning that the isolates with high performance values under humid conditions did not exhibit the same high values under dry conditions. Because the environmental conditions are erratic between the years, the lack of a constant selection pressure in the same direction reduces the probability of achieving a speciation event per environment. The phenotypic data of the DON content in harvested grain showed a high correlation with the aggressiveness data. An association mapping study with 17 candidate genes for aggressiveness using a population of 100 isolates of FC inoculated on bread wheat revealed the significant association of the HOG1 gene, explaining 10.29% of the genetic variance of aggressiveness and 6.05% of the genetic variance corresponding to the accumulation of DON in mature grain. HOG1 is a kinase-like protein involved in the communication within the oxidative metabolism of the fungus. In a similar study using the same population of FC isolates and the same candidate genes but rye as host, the gene CUT showed a significant association with aggressiveness, explaining 16.05% of the genetic variance. The CUT gene encodes a cutinase protein, belonging to the secretome and involved in the process of unleashing the membranes and cuticles of the host plant. Taken together, our results suggest that i) field trials of breeding for resistance to FC in cereals should be carried out in several years to properly account for the genotype-by-year interaction; ii) despite the fact that molecular communication may present some type of host specificity the high plasticity guarantees that the effects on the phenotype are very similar among the cereal hosts; and iii) the high genetic correlation of aggressiveness for different cereals invites to involve non-cereal crops in the rotation plans focused on Fusarium disease management.
Pearl millet breeding in West Africa : steps towards higher productivity and nutritional value
(2018) Pucher, Anna Ida; Haussmann, Bettina
The enormous human population growth in West Africa (WA) in combination with serious production constraints is very problematic condition for food security. The alarming status of micronutrient deficiency in WA exacerbates this situation. For smallholder farmers improved and nutritious crop varieties derived from plant breeding could be a major contributor to enhancing agricultural productivity and reducing malnutrition. Pearl millet (Pennisetum glaucum (L.) R. Br.) is due to its high tolerance to drought and heat, capable to grow under very harsh environments, and is therefore a staple crop in Sahelian WA. Development of multiple pearl millet breeding approaches will be crucial to exploit the potential of this crop.The main goal of this study was to establish a scientific basis for more efficient pearl millet breeding in WA with a specific focus on achieving higher productivity and nutritional value. In order to accomplish this goal, the following objectives were defined: (I) to characterize a broad set of WA pearl millet accessions and to investigate their diversity and geographic patterns based on their phenotype; (II) to identify the potential and strategies to increase the micronutrient level in WA pearl millet; (III) to evaluate the performance of population hybrids and to derive initial strategies of pearl millet hybrid breeding in WA based on combining ability and heterotic patterns; and (IV) to identify molecular markers for the male-fertility restoration locus (Rf) for the A4 cytoplasmic-genic male-sterility (CMS) system in pearl millet using a genotyping-by-sequencing (GBS) based linkage map. The major results and conclusions of the four studies are summarized in the following:Characterization of a collection of 360 WA pearl millet landraces at six sites in WA identified wide ranges for 12 agro-morphological traits, which indicated a tremendous diversity. Principal component analysis revealed very large diversity within individual countries, and a high genetic admixture among WA pearl millet landraces. The high admixture indicates that heterotic grouping based on morphological distance or geographic distance is not possible. The published data of this study gives national breeders a basis to utilize this germplasm.In the second trial, pearl millet grain iron and zinc densities showed significant genetic variation in a set of 72 WA landraces evaluated at three sites and moderate-to-high heritability, which emphasizes a high potential for biofortification. Identified landraces with moderately high and stable micronutrient densities appear suitable for use in future WA biofortification breeding. Due to significant positive correlations among grain iron, zinc and other mineral densities and non-significant correlations between grain yield and mineral densities, selection for high grain iron and zinc density can be performed simultaneously without a negative effect on grain yield or contents of other micronutrients.The third trial evaluated 100 population hybrids and their 20 parental populations (with four parental open-pollinated varieties from each of five WA countries) at six environments and showed hybrid superiority of, on average, 16.7% compared to their parental populations (with a max. of 73%), reflecting the great potential of hybrid breeding. The mean grain yield of hybrids based on inter-country crosses did not differ significantly from intra-country crosses. Geographic distance between parents was not correlated with panmictic midparent heterosis, indicating that heterotic grouping based on geographic distance is not expedient. However, crosses between accessions from Niger/Nigeria and Senegal were outstanding, thus initial heterotic pools could be based on this information. In the long term, sustainable pearl millet hybrid breeding will require combining ability studies to develop heterotic groups.Within the fourth trial, a high-density linkage map based on single nucleotide polymorphism (SNP) markers produced by GBS was generated using a F2 mapping population, which segregated for fertility restoration of the A4 CMS system. A major Rf locus was found on linkage group 2, which was verified by cross-validation showing a very high quantitative trait locus (QTL) occurrence (97%). The QTL explained 14.5% of the phenotypic variance, which was below expectation because the segregation ratio of male-fertile and male-sterile plants (3:1) indicated monogenic dominant inheritance of this trait. The two KASP markers developed for the QTL will support high-throughput screening for the Rf locus and will facilitate the development of male parental pools exhibiting the fertility restoration, which is an essential step to enable economic pearl millet hybrid seed production. We can conclude that WA pearl millet breeding has the potential to increase the pearl millet productivity and nutritional value by utilizing the enormous pearl millet diversity in hybrid and biofortification breeding programs.
The porcine intestinal microbiota : studies on diversity and dietary impact
(2018) Burbach, Katharina; Seifert, Jana
The entirety of microbial communities within the gastrointestinal tract is referred to as intestinal microbiota and is predominantly composed of bacteria. Interactions between the microbiota, the host and the diet are essential for maintaining a healthy and functional intestinal ecosystem. The overarching aim of this thesis was the characterization of the porcine intestinal microbiota and further to enhance knowledge about the effects of varying diets. High-throughput sequencing of the 16S rRNA gene facilitates exploration of the taxonomic composition of the microbiota. However, the respective findings may be impaired by methodological variations. Thus, within this thesis, commercial DNA extraction kits are evaluated for their suitability in porcine microbiota analysis. The tested extractions yield into variations of quantity and quality of DNA. The DNA extracts are further used to elucidate the structure of the microbiota by a rapid fingerprinting (Terminal Restriction Fragment Length Polymorphism) and high-resolution sequencing (Illumina amplicon sequencing). While different variable regions of the 16S rRNA gene vary in the taxonomical resolution, sequencing analyses exhibit a good comparability of the two regions V1-V2 and the V5-V6. Furthermore, the microbiota profiles reveal a high consistency by the fingerprinting and sequencing approach but are distinguished by the different DNA extraction kits. Based on criteria of DNA extraction and the depicted microbiota composition, it is recommended to use the FastDNA SPIN Kit for Soil for further analysis of porcine intestinal microbiota. Subsequently, these methodological findings are applied to investigate the impact of varying diets. Illumina amplicon sequencing of the V1-V2 region of the 16S rRNA gene reveals different microbiota structures when diets are solely composed of rye or triticale. Besides the taxonomic analyses of ileal digesta and fecal samples, the concentrations of bacterial metabolites in feces are determined. In summary, rye promotes an increased abundance of saccharolytic bacteria like Lactobacillus, Bifidobacterium, and Prevotella and results in higher concentrations of bacterial metabolites in fecal samples. In contrast, a diet based on triticale is associated with an increased abundance of Clostridium sensu stricto, which may indicate an enhanced cellulolytic potential of the microbiota. When the crude protein content is increased (18%), compared to a lower content (14%), an increased abundance of Lactobacillus is demonstrated in microbiota of ileal digesta samples. However, the content of crude protein did not affect the overall microbiota significantly. In addition, dietary supplementation with probiotic Bacillus spp. shows no effect. In conclusion, these dietary effects on microbiota are considered together with results of a protein digestibility analysis. Moreover, an impact of dietary calcium and phosphorus in combination with different sources of dietary protein is analyzed by fingerprinting approach of digesta samples. Here, the content of calcium-phosphorus shows significant effects on the microbiota of caecal digesta and the putative identities of discriminative variables are determined by a cloning-sequencing approach. Similar, 16S rRNA gene sequencing reveals a significant impact of dietary calcium-phosphorus on the overall fecal microbiota without indicating specific discriminating variables. In combination with the results of a meta-proteomic approach, a gradual adaptation on dietary changes is indicated and consequently, a prolonged adaptation time of three to four weeks is recommended for diet-microbiota studies. This thesis includes a comprehensive analysis of the microbiota across and along the gastrointestinal tract of piglets and explores the dietary inclusion of four levels of insect larvae meal. Feeding insects represent an alternative source of dietary protein, whereby the increased content of chitin indicates a potential shift in microbiota composition compared to a control diet. However, in this case, the structural analysis demonstrates no effects on the overall microbiota’s structure. However, a pairwise comparison between diets reveals significant effects on the microbiota of digesta samples of the small intestine. Dietary inclusion of 5% insect meal increases the abundance of Lactobacillus, whereas the control treatment promotes Bifidobacterium. In conclusion, the results of the present thesis emphasize the importance of standardization within 16S rRNA gene based studies of the porcine intestinal microbiota. Furthermore, the necessity of studying various sampling sites combined with multidisciplinary approaches is demonstrated.
Zweinutzungshuhn – was ist das? Umfrage unter Landwirt*innen und Geflügelhalter*innen in Deutschland 2022
(2023) Gebhardt, Beate; Bermejo, Gabriela; Imort-Just, Annik; Kiefer, Lukas; Zikeli, Sabine; Hess, Sebastian
To comply with the ban on chick culling that has been in effect since January 2022, the Federal Ministry of Food and Agriculture proposes three alternatives, including the hatching of dual-purpose chickens. In addition to the breeding and economic challenges of establishing dual-purpose animals in the value chain, the inconsistent understanding of what a dual-purpose chicken actually is and how its characteristics can be successfully communicated to consumers are seen as challenges. The goal of this working report is to present what a dual-purpose chicken is and what understanding farmers have of it. The German nationwide online survey among farmers and poultry farmers regarding the understanding and future of dual-purpose chickens was conducted in autumn 2022 as part of the EIP-Agri project "ZweiWert." The EIP project titled "Building Value Chains for Dual-Purpose Chickens in Baden-Württemberg" (ZweiWert) is funded by the Ministry of Food, Rural Areas and Consumer Protection of Baden-Württemberg from 01/2022 to 12/2024. Project partners include the Naturland Association of Baden-Württemberg, several departments of the University of Hohenheim, and many partners from agricultural production and marketing.