Browsing by Subject "Pflanzen"

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Abgabe von bodenbürtigem Lachgas über Pflanzen
(2003) Ferch, Norbert-Jakob; Römheld, Volker
The aim of this work was to explore and to rank the different ways and forms of transition of N2O through plants (dissolved in water and transported with the transpiration or gaseous through aerenchyma). To achieve this goal an experimental set-up had to be realized that allowed the determination of possible N2O emissions by plants, the determination of different ways of transition of N2O through the plant and the determination of different influencing factors (e.g. N2O concentration) on the N2O emissions. In the beginning experiments with closed chambers and with ?controlled opened chambers? were conducted in comparison to each other. In the experiments with closed chambers samples were drawn by means of molecular sieves and vacutainers. N2O concentrations of the samples were measured with a GC (gas chromatograph type HP 5890) equipped with an ECD (electron capture detector). Besides the two methods mentioned above in order to determine the N2O concentrations within the experiments with the ?controlled opened chambers? a third method was used for N2O measurement by means of a photo acoustic online measuring machine. The accuracy of the photo acoustic measurement was evaluated with the GC. For the questions of interest the photo acoustic measurement showed to be the best to determine differences of N2O emissions between different experimental treatments. The experiments that were taken in consideration were conducted in a ?controlled opened system? because in closed chambers CO2 concentration decreased rapidly. Additionally, the air in the closed chambers became saturated in water vapour within a few minutes. These two factors lead to inhibited growth of the plants and to undesired influences on the N2O measurements. The ?controlled opened system? consisted of a root and a shoot compartment. Both compartments were separated airtight from each other and from the surroundings. The root compartments were enriched with a definite amount of N2O. The N2O concentrations measured in the shoot compartments of the systems with N2O enrichment in the root compartment were compared with measurements of systems without N2O enrichment and measurements of ambient air. The necessity to divide the root compartment from the shoot compartment airtight was realised with a material on the basis of silicone that is usually used to make prints of teeth (Optosil, from Haereus) and a sealing mass (Prestik AE hellgrau, from Bostik GmbH). To determine the different factors potentially influencing the N2O emission through plants a hydroponical culture system was established that allowed controlling the following factors: concentration of nutrients, pH-factor, concentration of different water soluble gases (e. g. N2O, CO2) and the ratio between water and gas filled space in the root compartment. As experimental plants sunflower (Helianthus annuus cv. Frankasol), barley (Hordeum vulgare cv. Scarlet), rice (Oryza sativa cv. 94D-22) and corn (Zea mays cv. Helix) were used. For the experiment with sunflower (no aerenchyma, N2O dissolved in water available only) a relationship between N2O concentration in the root compartment, the emitted amount of N2O by the shoots and the intensity of transpiration in a diurnal pattern was found. In systems with gaseous availability of N2O in the root compartment the observed emissions were higher than in systems with availability of N2O dissolved only in water. From this it could be concluded, that gaseous N2O is better available for plants than N2O dissolved in water. Similar results were obtained from experiments with barley. The only difference was that the highest N2O emissions were observed in systems with availability of N2O dissolved in water only. The possible N2O emission through aerenchyma was checked with rice plants. In these experiments a pronounced diurnal pattern of the N2O emissions was also found. This lead to the conclusion that aerenchyma only have a small influence on the N2O emissions out of the root compartment through rice plants. Because the N2O emission in the three experiments described above followed the diurnal pattern of the transpiration, it was concluded that N2O was transported with the transpiration water flow from the root (compartment) to the shoot (compartment). The experiments with corn showed for all treatments (control and availability of N2O in gaseous form or dissolved in water) a net N2O depletion in the shoot compartment for night (darkness) and day (light) respectively, thus leading to the conclusion that N2O can be metabolised and used as a nitrogen source. All in all the experiments showed that the main way of transition of N2O through plants is water dissolved with the transpiration water flow and not gaseous (through aerenchyma).
Measuring and modelling carbon stocks in rubber (Hevea brasiliensis) dominated landscapes in Subtropical China
(2019) Yang, Xueqing; Cadisch, Georg
Rubber plantation has been rapidly expanded in Montane Mainland South East Asia in past decades. Limited by long-term monitoring data availability, the impacts of environmental change on rubber trees carbon stock development still not fully understood. Against global warming background, in order to better facilitate regional forest management, we applied synergetic approach combining field survey and modelling tools to improve predictions of dynamic carbon stock changes. The trade-off analysis regarding to rubber carbon stock and latex production optimization was further discussed in view of sustainable rubber cultivation. The first study explored the impact of regional land-use changes on landscape carbon balances. The Naban River Watershed National Nature Reserve (NRWNNR), Xishuangbanna, China, was selected as a case study location. Carbon stocks were evaluated using the Rapid Carbon Stock Appraisal (RaCSA) method based on tree, plot, land use and landscape level assessments of carbon stocks, integrating field sampling with remote sensing and GIS technology. The results showed that rubber plantations had larger time-averaged carbon stocks than non-forest land use types (agricultural crops, bush and grassland) but much lower than natural forest. During 23 years (1989-2012), the whole landscape of the nature reserve (26574 ha) gained 0.644 Tg C. Despite rubber expansion, the reforestation activities conducted in NRWNNR were able to enhance the carbon stocks. Regional evaluation of the carbon sequestration potential of rubber trees depends largely on the selection of suitable allometric equations and the biomass-to-carbon conversion factor. The second study developed generic allometric equations for rubber trees, covering rotation lengths of 4-35 years, within elevation gradient of 621-1,127 m, and locally used rubber tree clones (GT1, PRIM600, Yunyan77-4) in mountainous South Western China. Allometric equations for aboveground biomass (AGB) estimations considering diameter at breast height (DBH), tree height, and wood density were superior to other equations. We also tested goodness of fit for the recently proposed pan-tropical forest model. The results displayed that prediction of AGB by the model calibrated with the harvested rubber tree biomass and wood density was more accurate than the results produced by the pan-tropical forest model adjusted to local conditions. The relationships between DBH and height and between DBH and biomass were influenced by tapping, therefore biomass and C stock calculations for rubber have to be done using species-specific allometric equations. Based on the analysis of environmental factors acting at the landscape level, we noticed that above- and belowground carbon stocks were mostly affected by stand age, soil clay content, aspect, and planting density. The results of this study provide reference for reliable carbon accounting in other rubber-cultivated regions. In the last study, we explored how rubber trees growth and production response to climate change and regional management strategies (cultivation elevation, planting density). We applied the process-based Land Use Change Impact Assessment tool (LUCIA) calibrated with detailed ground survey data to model tree biomass development and latex yield in rubber plantations at the tree, plot and landscape level. Model simulation showed that during a 40-year rotation, lowland rubber plantations (< 900m) grew quicker and had larger latex yield than highland rubber (≧900m). High planting density rubber plantations showed 5% higher above ground biomass than those at low- and medium-planting density. The mean total biomass and cumulative latex yield per tree over 40 years increased by 28% and 48%, respectively, when climate change scenarios were modelled from baseline to highest CO2 emission scenario (RCP 8.5). The same trend of biomass and latex yield increase with climate change was observed at plot level. Denser plantations had larger biomass, but the cumulative latex production decreased dramatically. The spatially explicit output maps produced during modelling could help maximize carbon stock and latex production of regional rubber plantations. Overall, rubber-based system required for appropriate monitoring scale in both temporal aspect (daily-, monthly-, and yearly-level) and in spatial aspect (pixel-, land use-, watershed-, and landscape- level). The findings from present study highlighted the important application of ecological modelling tools in nature resources management. The lessons learned here could be applicable for other rubber-cultivated regions, by updating with site-specific environmental variables. The significant role of rubber tree not limited in its nature latex production, it also lies in its great carbon sequestration potential. Our results here provided entry point for future developing comprehensive climate change adaption and mitigation strategies in South East Asia. By making use of interdisplinary cooperation, the sustainable rubber cultivation in Great Mekong Regions could be well realized.
Multi-objective and multi-variate global sensitivity analysis of the soil-crop model XN-CERES in Southwest Germany
(2021) Witte, Irene; Streck, Thilo
Soil-crop models enjoy ever-greater popularity as tools to assess the im- pact of environmental changes or management strategies on agricultural production. Soil-crop models are designed to coherently simulate the crop, nitrogen (N) and water dynamics of agricultural fields. However, soil-crop models depend on a vast number of uncertain model inputs, i.e., initial conditions and parameters. To assess the uncertainty in the simulation results (UCSR) and how they can be apportioned among the model inputs of the XN-CERES soil-crop model, an uncertainty and global sensitivity analysis (GSA) was conducted. We applied two different GSA methods, moment-independent and variance-based methods in the sense of the Factor Prioritization and the Factor Fixing setting. The former identifies the key drivers of uncertainty, i.e., which model input, if fixed to its true value, would lead to the greatest reduction of the UCSR. The latter identifies the model inputs that cannot be fixed at any value within their value range without affecting the UCSR. In total we calculated six sensitivity indices (SIs). The overall objective was to assess the cross-sub-model impact of parameters and the overall determinability of the XN-CERES applied on a deep loess soil profile in Southwest Germany. Therefore, we selected 39 parameters and 16 target variables (TGVs) to be included in the GSA. Furthermore, we assessed a weekly time series of the parameter sensitivities. The sub-models were crop, water, nitrogen and flux. In addition, we also compared moment-independent (MI) and variance-based (VB) GSA methods for their suitability for the two settings. The results show that the parameters of the TGVs of the four groups cannot be considered independently. Each group is impacted by the parameters of the other groups. Crop parameters are most important, followed by the Mualem van Genuchten (MvG) parameters. The nitrate (NO3-) content and the matric potential are the two TGVs that are most affected by the inter- action of parameters, especially crop and MvG parameters. However, the model output of these two TGVs is highly skewed and leptokrutic. Therefore, the variance is an unsuitable representation of the UCSR, and the reliability of the variance-based sensitivity indices SIVB is curtailed. Nitrogen group parameters play an overall minor role for the uncertainty of the whole XN-CERES, but nitrification rates can be calibrated on ammonium (NH4+) measurements. Considering the initial conditions shows the high importance of the initial NO3-; content. If it could be fixed, the uncertainty of crop groups’ TGVs, the matric potential and the N content in the soil could be reduced. Hence, multi-year predictions of yield suffer from uncertainty due to the simulated NO3-; content. Temporally resolved parameter show the big dependence between the crop’s development stage and the other 15 TGVs becomes visible. High temporally resolved measurements of the development stage are important to univocally estimate the crop parameters and reduce the uncertainty in the vegetative and generative biomass. Furthermore, potential periods of water and N-limiting situations are assessed, which is helpful for deriving management strategies. In addition, it become clear that measurement campaigns should be conducted at the simulation start and during the vegetation period to have enough information to calibrate the XN-CERES. Regarding the performance of the different GSA methods and the different SIs, we conclude that the sensitivity measure relying on the Kolmogorov-Smirnov metric (betaks) is most stable. It converges quickly and has no issues with highly skewed and leptokrutic model output distributions. The assessments of the first-effect index and the betaks provide information on the additivity of the model and parameters that cannot be fixed without impacting the simulation results. In summary, we could only identify three parameters that have no direct impact on any TGV at any time and are hence not determinable from any measurements of the TGVs considered. Furthermore, we can conclude that the groups’ parameters should not be calibrated independently because they always affect the uncertainty of the selected TGV directly or via interacting. However, no TGV is suitable to calibrate all parameters. Hence, the calibration of the XN-CERES requires measurements of TGVs from each group, even if the modeler is only interested in one specific TGV, e.g., yield. The GSA should be repeated in a drier climate or with restricted rooting depth. The convergence of the values for the Sobol indices remains an issue. Even larger sample sizes, another convergence criteria or graphical inspection cannot alleviate the issue. However, we can conclude that the sub-models of the XN-CERES cannot be considered in- dependently and that the model does what it is designed for: coherently simulating the crop, N and water dynamics with their interactions.
Plant ammonium transporter (AMT) integration in regulatory networks
(2016) Straub, Tatsiana; Ludewig, Uwe
Ammonium is a ubiquitous key nutrient in agricultural soils and the preferred nitrogen source for plants. However, excessive ammonium accumulation represses plant growth and development. Ammonium is taken up by plant cells via high-affinity ammonium transporters (AMTs). Six AMT genes were identified in Arabidopsis, which are separated in two distinct clades, five AMT1s and one AMT2. In the plasma membrane, AMT proteins form homo- and heterotrimers with extra-cytoplasmic N-termini and cytoplasmic C-termini. In addition to transcriptional and post-transcriptional control of AMTs by ammonium, phosphorylation in the C-terminus serves as a rapid allosteric switch of the AMT activity and prevents further internal ammonium accumulation. In a physiological screen, a kinase (CIPK23) was identified, which directly regulates ammonium transport activity under high-NH4+ conditions. Interestingly, CIPK23 is already known to regulate nitrate and potassium uptake in roots. Lesion of the CIPK23 gene significantly increased ammonium uptake, but caused growth inhibition. As expected, cipk23 plants were also limited in potassium accumulation, but high potassium availability failed to rescue the cipk23 phenotype. Furthermore, cipk23 plants were more susceptible to methylammonium (MeA), a non-metabolizable analogue of ammonium. The sensitivity to MeA was lost upon genetic suppression of AMT1 genes in the cipk23 background. The data suggest that CIPK23 directly phosphorylates AMT1s in a complex with CBL1 (calcineurin B-like protein) and thereby regulates transport activity. The expression of the CIPK23 and the CBL1 genes were ammonium-dependent and increased when N-starved plants were resupplied with ammonium. Furthermore, cbl1 mutants had enhanced NH4+ accumulation; this phenocopies the larger ammonium uptake in the cipk23 loss-of-function mutant. In vivo experiments demonstrated bimolecular interaction between CIPK23, AMT1;1, and AMT1;2, but not with AMT2;1, suggesting direct phosphorylation of AMT1-type ammonium transporters by CIPK23. However, Western blot analysis with the cipk23 mutant suggested that the loss of the kinase was not sufficient to completely abolish AMT1;1 and AMT1;2 phosphorylation, indicating several independent pathways to regulate ammonium transport activity in AMT trimers. The data identify complex post-translational regulation of ammonium transporters via the CBL1–CIPK23 pathway, which ensures reduction of AMT1 activity and suppression of ammonium uptake under high external NH4+ concentrations.
Spatial and temporal variations of microorganisms in grassland soils : influences of land-use intensity, plants and soil properties
(2019) Boeddinghaus, Runa S.; Kandeler, Ellen
Grassland ecosystems provide a wide range of services to human societies (Allan et al., 2015) and plants and soil microorganisms have been identified as key drivers of ecosystem functioning (Soliveres et al., 2016). Therefore, understanding soil microbial distributions and processes in agricultural grassland soils is crucial for characterizing these ecosystems and for predicting how they may shift in a changing environment. Yet we are only beginning to understand these complex ecosystems, which account for about 26% of the world’s terrestrial surface (FAOSTATS, 2018), making it especially urgent to gain better insights into the effects of land-use intensity on soil microbial properties and plant-microbe interactions. This thesis was conducted to evaluate the impact land-use intensity has on soil microbial biogeography of grasslands with respect to both spatial patterns and temporal changes in soil microbial abundance, function (in terms of enzyme activities), and community composition. It also investigated the relationships between plants and the spatial and temporal distributions of soil microorganisms. Thereby both, land-use intensity effects and plant-microbe interactions, were assessed in light of ecological niche and neutral theory. This thesis is based on three observational studies conducted on from one to 150 continuously farmed, un-manipulated grassland sites in three regions of Germany within the Biodiversity Exploratories project (DFG priority program 1374). The first study assessed the effects of land-use intensity and physico-chemical soil properties on the spatial biogeography of soil microbial abundance and function in 18 grasslands sites from two of the three regions, sampled at one time point. The second study analyzed spatial and temporal distributions of alpha- and beta-diversity of arbuscular mycorrhizal fungi in a low land-use intensity grassland with six sampling time points across one season. The third study investigated both legacy and short-term change effects of land-use intensity, soil physico-chemical properties, plant functional traits, and plant biomass properties on temporal changes in soil microbial abundance, function, and community composition in 150 grassland sites across three regions, with particular regard to direct and indirect land-use intensity effects. Although the three studies used different approaches and assessed different soil microbial properties, general patterns were detectable. Abiotic soil properties, namely pH, nitrogen content, texture, and bulk density played fundamental roles for spatial and temporal microbial biogeography. Since these factors were specific and unique for each investigated site, they formed the background based on which other processes occurred. In addition to abiotic soil properties, impacts of land-use intensity and plants were detected, though to various degrees in the three studies. Land-use intensity played a much smaller role than anticipated in the first and third study. No influence on the spatial distribution of soil microbial abundance and function could be detected in the first study. In the third study, short-term changes in and legacy effects of land-use intensity played a minor role with respect to short-term changes in soil microbial abundance, function, and community composition. Where detected, changes in land-use intensity had a direct and negative effect on soil microbial properties in structural equation modelling; i.e., increases in land-use intensity reduced, e.g., soil microbial enzyme activities, while legacy effects of land-use intensity were shown to act both directly and indirectly on soil microbial properties. Thereby indirect legacy effects were mediated via plant functional traits. Only one of the three studies detected minor plant diversity effects on soil microbial properties. Instead, functional properties of the plant communities, i.e., plant functional traits, biomass, and nutritional quality, were significantly related to spatial and temporal distributions of soil microorganisms. Finally, the findings of the three studies suggest that processes related to niche and neutral theory both drive spatial and temporal patterns of soil microbial properties at the investigated plot scale (up to 50 m × 50 m). This thesis concluded that in order to gain deeper insights into the complex functions and processes occurring in grassland ecosystems, a multidisciplinary approach investigating fundamental physico-chemical site characteristics, microbial soil properties, and plants is necessary. The results of the thesis suggest that focus be turned to functional properties of plant and microbial communities, as they are closely intermingled, provide more detailed insights into plant-microbe interactions, and are able to reflect effects of human impacts on grassland soils better than diversity measures.
Spatial undergrowth species composition in oil palm (Elaeis guineensis Jacq.) in West Sumatra
(2003) Germer, Jörn Uwe; Sauerborn, Joachim
The area planted to oil palm expanded during the last decades substantially, making it become the world's second most important oil crop. Despite its economic significance the oil palm remains remarkably unknown. Little attention is paid also to the oil palm undergrowth, though important in stabilizing the agro-ecosystem in plantations. Comprehensive knowledge of undergrowth species adapted to specific ecological niches in oil palm plantations is essential to investigate their function in and potential benefit to the oil palm agro-ecosystem. The objectives of the conducted research were to develop a reproducible approach for phytosociological investigation in oil palm plantations and to accomplish a general inventory of the vascular plants associated with oil palm in a plantation in West Sumatra. Additionally it was aimed to study the undergrowth heterogeneity within the fields and the distribution of species in the plantation in response to solar radiation below the palm canopy, soil type and physical and chemical soil parameters. A rich diversity of 298 species, 186 dicotyledonae, 77 monocotyledonae and 35 pteridophyta (ferns and allies), representing 81 families was identified in the research area. Similar to rainforests, plants with a high consistency were few, while most of the species occurred only sporadically in the oil palm undergrowth. In average 36 species were found in each of the 100 sampled relevés. The 8 most frequent species were identified as an abstract plant community: Mikania micrantha H.B.&K., Pouzolzia zeylanica Benn., Ageratum conyzoides L., Sporobolus diander Beauv., Nephrolepis biserrata (Sw.) Schott., Pityrogramma calomelanos (L.) Link, Lygodium microphyllum (Cav.) R.Br. and Stenochlaena palustris Bedd. Due to particular management practice, oil palm fields can be zoned in harvesting path, palm circle and inter-row. Species that were mainly found in the inter-row were: Diplazium esculentum (Retz.) Sw, Cyclosorus interruptus (Willd.) H.Ito, Nephrolepis biserrata and Christella dentate (Forssk.) Brownsey & Jermy. Plants that were found primarily in the other zones were small herb species such as Hedyotis corymbosa Lam., Limnophila rugosa Merrill, Borreria setidens (Miq.) Boldingh and Peperomia pellucida H.B.&K., the sedges Fimbristylis miliacea Vahl and Cyperus kyllingia Endl. as well as the grass Sporobolus diander. It was found that the palm canopies developed slower on histosol than on fluvisol and assumed that the main reason for this difference was the lower nutrient pool in low-density organic soil. Melliferous species, which are often important as hosts for pest antagonists, were infrequent where less light was available. In the inter-row a distinct shift from a creeper and grass to a fern and non-creeper dicotyledonae dominated undergrowth was observed with falling levels of solar radiation. Species consistently more frequent in less shaded sampling sites throughout the research area were: Basella alba Linn., Calopogonium muconoides Desv., Commelina diffusa Brum.f., Imperata cylindrica Beauv., Pueraria phaseoloides Benth. and Sporobolus diander whereas Ageratum conyzoides, Christella dentata, Diplazium esculentum, Peperomia pellucida, Phyllanthus debilis Willd., Pouzolzia zeylanica and Sparganophorus villantii Crantz preferred more shaded environments. The soil analyses revealed that the soil carbon content was not only distinctly different between histosol and fluvisol, but also between individual sites on the two soil types. Next to the carbon content the effective cation exchange capacity varied largely between sites. The physical soil properties were stable within the sites, while the chemical properties were significantly influenced by fertilization. Species abundance per relevé was significantly higher on fluvisol than on histosol, while the difference in the total number of species between the soil types was small. 11 species showed a preference towards low soil carbon content: Ceratopteris thalictroides (L.) Brongn., Christella dentata, Christella parasitica (L.) Lev., Diplazium esculentum, Eleusine indica (L.) Gaertn., Hedyotis corymbosa, Pleocnemia irregularis (C.Presl) Holtt., Polygonum barbatum L., Selaginella plana Hieron., Sphaerostephanos polycarpus (Bl.) Copel. and Stachytarpheta indica Vahl. Accordingly the presence of two species: Borreria latifolia (Aubl.) K. Schum. and Dicranopteris linearis J. Underw. augmented with increasing soil carbon content. In the sampling sites marked by high ECEC ferns were dominant. On fluvisol 11 out of 18 species that occurred more frequently where the ECEC was higher were ferns and on histosol 3 out of 12 species respectively. The distinct difference of soil carbon content blanketed, apart form the ECEC possible effects of other soil properties on the undergrowth species composition.
The role of soil properties and fertilization management in pathogen defense and plant microbial interactions in the rhizosphere of lettuce (Lactuca sativa L.)
(2022) Windisch, Saskia Helen; Neumann, Günter
Soil microorganisms are involved in nearly all relevant soil processes and considered as key players in agro-ecosystems. This is particularly relevant for the rhizosphere which is created by the activity of plant roots with dynamic impact on microbial communities, their diversity and activity. Both, beneficial but also pathogenic plant-microbial interactions in the rhizosphere are driven by root exudates and other root-induced modifications in rhizosphere chemistry, which are highly variable in space, time, composition and intensity. The physicochemical properties of the rhizosphere are influenced by numerous external factors including nutrient availability, biotic and abiotic stress, soil properties or plant genotypic variation but the related consequences for plant-microbial interactions and the consequences for plant performance and health status are still poorly understood. In this context the present study was initiated to investigate (i) the influence of the soil type on root exudation and the composition of the rhizosphere solution (ii) their impact on interactions with soil pathogens and beneficial rhizosphere microorganisms and (iii) the effect of long-term fertilization strategies (organic vs. mineral fertilization), using lettuce (Lactuca sativa) as a well-characterized model plant for studies on plant-microbial interactions in the rhizosphere.
Towards a better understanding of land surface exchange processes over agricultural crop stands
(2020) Bohm, Kristina; Streck, Thilo
Weather and climate models are useful tools for projecting the influence of global climate change on the regional scale. These models are critically dependent on an accurate representation of soil-plant-atmosphere interactions, which are simulated by Land Surface Models (LSMs). The present PhD thesis was designed to improve the representation of land surface exchange processes of croplands in the Noah-MP land surface model. This thesis aims: a) to elucidate the nature of the energy imbalance over a winter wheat stand and to identify the appropriate post-closure method for the study region Kraichgau, southwest Germany; b) to improve the representation of the green vegetation fraction (GVF) dynamics of croplands in the Noah-MP for a more accurate computation of surface energy and water fluxes; and c) to determine the effect of aggregating different crop types with various shares into a single generic cropland class on the simulation of water and energy exchange between land surface and atmosphere.
Vergleichende Transkriptomanalyse und funktionelle Untersuchungen von enterohämorrhagischen Escherichia coli nach Kultivierung in Pflanzenmedium
(2020) Bufe, Thorsten; Schmidt, Herbert
Enterohemorrhagic Escherichia coli (EHEC) are human pathogens which are able to cause severe gastrointestinal diseases in humans. The gastrointestinal tract of cattle is considered as the main reservoir for EHEC and contaminated raw meat represents the primary source of infection. Yet there have been increasing reports over the last few decades of EHEC infections that were linked to the consumption of raw vegetables. Today it is generally accepted that EHEC bacteria are able to use plants as their secondary hosts, thus favouring the transmission to humans. To improve the understanding of this pathogen-plant interaction fundamental knowledge about the pathogens’ molecular adaptions towards plant material is urgently required. In the cope of this study the adaption of different EHEC strains towards components of the plant was examined. Therefore O157:H7 strain Sakai, O104:H4 strain C227-11phicu and O157:H strain 3072/96 were chosen as surrogates. In growth experiments performed with an artificial lettuce medium it could be shown that components of the lettuce were sufficient for the proliferation of the three strains. RNA-sequencing was performed to study the differential gene expression of the three strains after the growth in lettuce medium compared to the growth in M9 minimal medium. In order to compare genes according to standardized gene denotations, the differential gene expression analysis was performed on the basis of a shared genome including the genomes of the three pathogenic strains as well as the genome of Escherichia coli strain K-12 substrain MG1655. Analogous to the successful growth in presence of components of the plant an upregulation of genes involved in carbohydrate and peptide metabolism throughout all three strains was observed. Especially genes involved in the catabolism of lactose (lacZ), ribose (rbsAC) and xylose (xylF) were found to be uniformly upregulated. The greatest differences among the strains accounted for the regulation of motility and chemotaxis genes. O104:H4 strain C227-11phicu showed a strong upregulation of all three classes of the flagellar hierarchy (class I, II and III) in presence of plant derived compounds. These included genes involved in the establishment of the basal body hook structure (fli, flg), the synthesis of the flagellar filament (fliC), and the chemotaxis-system (che, tap, tar). In contrast, O157:H7 strain Sakai only featured upregulation of class I and class II genes. According to the transcriptional data both of these strains also showed increased swimming and swarming behaviour on motility plates in presence of lettuce extract. Solely O157:H- strain 3072/96, which is non-motile due to a deletion in the flhC gene, showed an upregulation of virulence factors encoded on the LEE pathogenicity island, including genes involved in the establishment of the T3SS (esc) and T3SS secreted effectors (esp). Interestingly, it was shown for O157:H- strain 3072/96 to have a powerful capacity to form biofilms in M9 minimal medium. Furthermore it was proven that the complementation of an intact flhC gene restored motility in O157:H- strain 3072/96. In this regard it could be shown that the deletion in flhC was not the mere reason for the augmented biofilm formation capacity. In addition to the biofilm formation, the strains’ potential to adhere to HT-29 cells was examined. Here a significantly increased adherence potential for O157:H- strain 3072/96 with respect to the motile strains could be observed, the lowest adherence potential was determined for O157:H7 strain Sakai. The results presented in this study clearly indicate that the different EHEC strains are capable to adapt towards the nutrient availability provided by their plantal host. It can be assumed that flagella and the chemotaxis system play a fundamental role in the finding and exploitation of the plant. Furthermore curli structures might play a crucial role in the initial adherence and the subsequent establishment of a biofilm on plant tissues. Presumably, besides the typical plant associated outbreak strain O157:H7 strain Sakai, there are further strains capable of utilizing their genetic repertoire in order to adapt towards the atypical environmental conditions within this niche. The findings of this study suggest that the strains, besides sharing multiple coinciding mechanisms, are able to adapt in a strain specific manner and use different strategies in coping with plants as their secondary hosts.