School of BioSciences - Research Publications

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    Deciphering the Interactions in the Root-Soil Nexus Caused by Urease and Nitrification Inhibitors: A Review
    Gupta, S ; Yildirim, S ; Andrikopoulos, B ; Wille, U ; Roessner, U (MDPI, 2023-06)
    Optimizing nitrogen (N) availability to plants is crucial for achieving maximum crop yield and quality. However, ensuring the appropriate supply of N to crops is challenging due to the various pathways through which N can be lost, such as ammonia (NH3) volatilization, nitrous oxide emissions, denitrification, nitrate (NO3−) leaching, and runoff. Additionally, N can become immobilized by soil minerals when ammonium (NH4+) gets trapped in the interlayers of clay minerals. Although synchronizing N availability with plant uptake could potentially reduce N loss, this approach is hindered by the fact that N loss from crop fields is typically influenced by a combination of management practices (which can be controlled) and weather dynamics, particularly precipitation, temperature fluctuations, and wind (which are beyond our control). In recent years, the use of urease and nitrification inhibitors has emerged as a strategy to temporarily delay the microbiological transformations of N-based fertilizers, thereby synchronizing N availability with plant uptake and mitigating N loss. Urease inhibitors slow down the hydrolysis of urea to NH4+ and reduce nitrogen loss through NH3 volatilization. Nitrification inhibitors temporarily inhibit soil bacteria (Nitrosomonas spp.) that convert NH4+ to nitrite (NO2−), thereby slowing down the first and rate-determining step of the nitrification process and reducing nitrogen loss as NO3− or through denitrification. This review aims to provide a comprehensive understanding of urease and nitrification inhibitor technologies and their profound implications for plants and root nitrogen uptake. It underscores the critical need to develop design principles for inhibitors with enhanced efficiency, highlighting their potential to revolutionize agricultural practices. Furthermore, this review offers valuable insights into future directions for inhibitor usage and emphasizes the essential traits that superior inhibitors should possess, thereby paving the way for innovative advancements in optimizing nitrogen management and ensuring sustainable crop production.
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    Insights into the Efficacy and Binding Mode of 1,4-Disubstituted 1,2,3-Triazoles - A New Class of Agricultural Nitrification Inhibitors
    Yildirim, SC ; Taggert, BI ; Walker, RM ; Roessner, U ; Wille, U (AMER CHEMICAL SOC, 2023-10-03)
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    Functional Traits 2.0: The power of the metabolome for ecology
    Walker, TWN ; Alexander, JM ; Allard, P-M ; Baines, O ; Baldy, V ; Bardgett, RD ; Capdevila, P ; Coley, PD ; David, B ; Defossez, E ; Endara, M-J ; Ernst, M ; Fernandez, C ; Forrister, D ; Gargallo-Garriga, A ; Jassey, VEJ ; Marr, S ; Neumann, S ; Pellissier, L ; Penuelas, J ; Peters, K ; Rasmann, S ; Roessner, U ; Sardans, J ; Schrodt, F ; Schuman, MC ; Soule, A ; Uthe, H ; Weckwerth, W ; Wolfender, J-L ; van Dam, NM ; Salguero-Gomez, R (WILEY, 2022-01)
    Abstract A major aim of ecology is to upscale attributes of individuals to understand processes at population, community and ecosystem scales. Such attributes are typically described using functional traits, that is, standardised characteristics that impact fitness via effects on survival, growth and/or reproduction. However, commonly used functional traits (e.g. wood density, SLA) are becoming increasingly criticised for not being truly mechanistic and for being questionable predictors of ecological processes. This Special Feature reviews and studies how the metabolome (i.e. the thousands of unique metabolites that underpin physiology) can enhance trait‐based ecology and our understanding of plant and ecosystem functioning. In this Editorial, we explore how the metabolome relates to plant functional traits, with reference to life‐history trade‐offs governing fitness between generations and plasticity shaping fitness within generations. We also identify solutions to challenges of acquiring, interpreting and contextualising metabolome data, and propose a roadmap for integrating the metabolome into ecology. We next summarise the seven studies composing the Special Feature, which use the metabolome to examine mechanisms behind plant community assembly, plant‐organismal interactions and effects of plants and soil micro‐organisms on ecosystem processes. Synthesis. We demonstrate the potential of the metabolome to improve mechanistic and predictive power in ecology by providing a high‐resolution coupling between physiology and fitness. However, applying metabolomics to ecological questions is currently limited by a lack of conceptual, technical and data frameworks, which needs to be overcome to realise the full potential of the metabolome for ecology.
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    Plant Growth Promotion and Heat Stress Amelioration in Arabidopsis Inoculated with Paraburkholderia phytofirmans PsJN Rhizobacteria Quantified with the GrowScreen-Agar II Phenotyping Platform
    Macabuhay, A ; Arsova, B ; Watt, M ; Nagel, KA ; Lenz, H ; Putz, A ; Adels, S ; Mueller-Linow, M ; Kelm, J ; Johnson, AAT ; Walker, R ; Schaaf, G ; Roessner, U (MDPI, 2022-11)
    High temperatures inhibit plant growth. A proposed strategy for improving plant productivity under elevated temperatures is the use of plant growth-promoting rhizobacteria (PGPR). While the effects of PGPR on plant shoots have been extensively explored, roots-particularly their spatial and temporal dynamics-have been hard to study, due to their below-ground nature. Here, we characterized the time- and tissue-specific morphological changes in bacterized plants using a novel non-invasive high-resolution plant phenotyping and imaging platform-GrowScreen-Agar II. The platform uses custom-made agar plates, which allow air exchange to occur with the agar medium and enable the shoot to grow outside the compartment. The platform provides light protection to the roots, the exposure of it to the shoots, and the non-invasive phenotyping of both organs. Arabidopsis thaliana, co-cultivated with Paraburkholderia phytofirmans PsJN at elevated and ambient temperatures, showed increased lengths, growth rates, and numbers of roots. However, the magnitude and direction of the growth promotion varied depending on root type, timing, and temperature. The root length and distribution per depth and according to time was also influenced by bacterization and the temperature. The shoot biomass increased at the later stages under ambient temperature in the bacterized plants. The study offers insights into the timing of the tissue-specific, PsJN-induced morphological changes and should facilitate future molecular and biochemical studies on plant-microbe-environment interactions.
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    Rapid and Inexpensive Assay for Testing the Efficiency of Potential New Synthetic Nitrification Inhibitors
    Yildirim, SC ; Walker, RM ; Roessner, U ; Wille, U (AMER CHEMICAL SOC, 2023-03-20)
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    Root Growth and Architecture of Wheat and Brachypodium Vary in Response to Algal Fertilizer in Soil and Solution
    Mau, L ; Junker, S ; Bochmann, H ; Mihiret, YE ; Kelm, JM ; Schrey, SD ; Roessner, U ; Schaaf, G ; Watt, M ; Kant, J ; Arsova, B (MDPI, 2022-02)
    Alternative, recycled sources for mined phosphorus (P) fertilizers are needed to sustain future crop growth. Quantification of phenotypic adaptations and performance of plants with a recycled nutrient source is required to identify breeding targets and agronomy practices for new fertilization strategies. In this study, we tested the phenotypic responses of wheat (Triticum aestivum) and its genetic model, Brachypodium (Brachypodium distachyon), to dried algal biomass (with algae or high or low mineral P) under three growing conditions (fabricated ecosystems (EcoFABs), hydroponics, and sand). For both species, algal-grown plants had similar shoot biomass to mineral-grown plants, taking up more P than the low mineral P plants. Root phenotypes however were strongly influenced by nutrient form, especially in soilless conditions. Algae promoted the development of shorter and thicker roots, notably first and second order lateral roots. Root hairs were 21% shorter in Brachypodium, but 24% longer in wheat with algae compared to mineral high P. Our results are encouraging to new recycled fertilization strategies, showing algae is a nutrient source to wheat and Brachypodium. Variation in root phenotypes showed algal biomass is sensed by roots and is taken up at a higher amount per root length than mineral P. These phenotypes can be selected and further adapted in phenotype-based breeding for future renewal agriculture systems.
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    Editorial: Salinity tolerance: From model or wild plants to adapted crops
    Qiu, Q-S ; Melino, VJ ; Zhao, Z ; Qi, Z ; Sweetman, C ; Roessner, U (FRONTIERS MEDIA SA, 2022-07-27)
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    Biochemical Changes in Two Barley Genotypes Inoculated With a Beneficial Fungus Trichoderma harzianum Rifai T-22 Grown in Saline Soil
    Gupta, SVK ; Smith, PMC ; Natera, SHA ; Roessner, U (FRONTIERS MEDIA SA, 2022-08-02)
    One of the most important environmental factors impacting crop plant productivity is soil salinity. Fungal endophytes have been characterised as biocontrol agents that help in plant productivity and induce resistance responses to several abiotic stresses, including salinity. In the salt-tolerant cereal crop barley (Hordeum vulgare L.), there is limited information about the metabolites and lipids that change in response to inoculation with fungal endophytes in saline conditions. In this study, gas chromatography coupled to mass spectrometry (GC-MS) and LC-electrospray ionisation (ESI)-quadrupole-quadrupole time of flight (QqTOF)-MS were used to determine the metabolite and lipid changes in two fungal inoculated barley genotypes with differing tolerance levels to saline conditions. The more salt-tolerant cultivar was Vlamingh and less salt tolerant was Gairdner. Trichoderma harzianum strain T-22 was used to treat these plants grown in soil under control and saline (200 mM NaCl) conditions. For both genotypes, fungus-colonised plants exposed to NaCl had greater root and shoot biomass, and better chlorophyll content than non-colonised plants, with colonised-Vlamingh performing better than uninoculated control plants. The metabolome dataset using GC-MS consisted of a total of 93 metabolites of which 74 were identified in roots of both barley genotypes as organic acids, sugars, sugar acids, sugar alcohols, amino acids, amines, and a small number of fatty acids. LC-QqTOF-MS analysis resulted in the detection of 186 lipid molecular species, classified into three major lipid classes-glycerophospholipids, glycerolipids, and sphingolipids, from roots of both genotypes. In Cultivar Vlamingh both metabolites and lipids increased with fungus and salt treatment while in Gairdner they decreased. The results from this study suggest that the metabolic pathways by which the fungus imparts salt tolerance is different for the different genotypes.
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    Measures of insulin sensitivity, leptin, and adiponectin concentrations in cats in diabetic remission compared to healthy control cats
    Gottlieb, S ; Rand, JS ; Ishioka, K ; Dias, DA ; Boughton, BA ; Roessner, U ; Ramadan, Z ; Anderson, ST (FRONTIERS MEDIA SA, 2022-07-29)
    OBJECTIVES: Firstly, to compare differences in insulin, adiponectin, leptin, and measures of insulin sensitivity between diabetic cats in remission and healthy control cats, and determine whether these are predictors of diabetic relapse. Secondly, to determine if these hormones are associated with serum metabolites known to differ between groups. Thirdly, if any of the hormonal or identified metabolites are associated with measures of insulin sensitivity. ANIMALS: Twenty cats in diabetic remission for a median of 101 days, and 21 healthy matched control cats. METHODS: A casual blood glucose measured on admission to the clinic. Following a 24 h fast, a fasted blood glucose was measured, and blood sample taken for hormone (i.e., insulin, leptin, and adiponectin) and untargeted metabolomic (GC-MS and LC-MS) analysis. A simplified IVGGT (1 g glucose/kg) was performed 3 h later. Cats were monitored for diabetes relapse for at least 9 months (270 days). RESULTS: Cats in diabetic remission had significantly higher serum glucose and insulin concentrations, and decreased insulin sensitivity as indicated by an increase in HOMA and decrease in QUICKI and Bennett indices. Leptin was significantly increased, but there was no difference in adiponectin (or body condition score). Several significant correlations were found between insulin sensitivity indices, leptin, and serum metabolites identified as significantly different between remission and control cats. No metabolites were significantly correlated with adiponectin. No predictors of relapse were identified in this study. CONCLUSION AND CLINICAL IMPORTANCE: Insulin resistance, an underlying factor in diabetic cats, persists in diabetic remission. Cats in remission should be managed to avoid further exacerbating insulin resistance.