1291. Abscisic acid-regulated water channels and their role in plant acclimation and tolerance to water stressChristina Paparokidou, 2014, magistrsko delo Opis: The yield of worldwide crop production has already been negatively affected by high salinity and water deficiency prevailing in many of the cultivated lands (Yan et al., 2013; Serraj et al., 2011; Golldack et al., 2011). Consequently, reduced crop production is a major problem in terms of food sustainability world-wide (Spiertz, 2013). Plants as sessile organisms have to dynamically and constantly cope with various types of stress in their environment. Although stress perception by plants remains elusive (Gan et al., 2010; Shachar-Hill et al., 2013; Wu et al., 2012), the stress-responsive mechanisms that follow are starting to be better understood (Wasilewska et al., 2008; Kohli et al., 2013; Osakabe et al., 2013).
Abscisic acid (ABA) is a central plant hormone produced in response to abiotic stress and has been shown to play important roles in plant acclimation and tolerance towards stress (Nakashima and Yamaguchi-Shinozaki, 2013; Osakabe et al., 2014). ABA accumulation triggers the expression of a plethora of genes within the plant cell (Liu et al., 2013). The ABA-regulated genes are various in nature, including enzymes involved in osmolyte and cell wall biosynthesis, detoxifying enzymes, enzymes for fatty acid metabolism, proteinase inhibitors, macromolecule protective proteins, lipid transfer proteins, ion transporters and water channels, transcription factors (TFs), protein kinases, protein phosphatases and proteinases (Roychoudhury et al., 2013; Rock, 2000).
In this literature review the role of water channel-encoding genes, namely aquaporins (AQPs), in plant water stress will be discussed. The aim of this study is to understand how ABA-regulated AQPs are able to contribute to the plant’s tolerance and acclimation during water stress. The knowledge gained from this study is important for the engineering of salt and drought resistant crops within the modern agricultural context, thus contributing to world’s crop sustainable production (Jacobs et al., 2011; Park et al., 2005; Kujur et al., 2013).
Ključne besede: Abscisic acid (ABA), ABA-regulated genes, aquaporins (AQPs), ABA-regulated AQPs, ABA-dependent water stress, root hydraulic conductance (Lpr), leaf hydraulic conductance (Kleaf), stomatal conductance (gs), AQP bioengineering
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1292. Phosphate availability and ectomycorrhizal symbiosis with Pinus sylvestris have independent effects on the Paxillus involutus transcriptomeChristina Paparokidou, Jonathan R. Leake, David J. Beerling, Stephen A. Rolfe, 2021, izvirni znanstveni članek Opis: Many plant species form symbioses with ectomycorrhizal fungi, which help them forage for limiting nutrients in the soil such as inorganic phosphate (Pi). The transcriptional responses to symbiosis and nutrient-limiting conditions in ectomycorrhizal fungal hyphae, however, are largely unknown. An artificial system was developed to study ectomycorrhizal basidiomycete Paxillus involutus growth in symbiosis with its host tree Pinus sylvestris at different Pi concentrations. RNA-seq analysis was performed on P. involutus hyphae growing under Pi-limiting conditions, either in symbiosis or alone. We show that Pi starvation and ectomycorrhizal symbiosis have an independent effect on the P. involutus transcriptome. Notably, low Pi availability induces expression of newly identified putative high-affinity Pi transporter genes, while reducing the expression of putative organic acid transporters. Additionally, low Pi availability induces a close transcriptional interplay between P and N metabolism. GTP-related signalling was found to have a positive effect in the maintenance of ectomycorrhizal symbiosis, whereas multiple putative cytochrome P450 genes were found to be downregulated, unlike arbuscular mycorrhizal fungi. We provide the first evidence of global transcriptional changes induced by low Pi availability and ectomycorrhizal symbiosis in the hyphae of P. involutus, revealing both similarities and differences with better-characterized arbuscular mycorrhizal fungi.
Ključne besede: Ectomycorrhizal symbiosis, Paxillus involutus, Pi transporters, Pi-starvation, Pinus sylvestris, RNA-seq.
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1293. Unravelling the molecular basis of hydroxyapatite weathering driven by the ectomycorrhizal fungus Paxillus involutusChristina Paparokidou, 2018, doktorska disertacija Opis: Ectomycorrhizal fungi (EMF) form symbiotic partnerships with tree roots and are able to chemically weather inorganic phosphorus (Pi)-rich minerals, supplying Pi to their host in return for photosynthates. The fungal-driven nutrient cycling from mineral weathering plays a pivotal role in ecosystems and crops productivity, as well as geochemical cycles. The aim of the study presented in this thesis is to unravel the molecular mechanisms by which the EM fungus Paxillus involutus weathers the Pi-rich mineral hydroxyapatite (HAP), either non-symbiotically or in symbiosis with its host tree Pinus sylvestris. Development of an artificial system to study P. involutus responses to varying concentration of Pi led to the identification of five high-affinity Pi transporter genes, of which the expression varies in an inversely proportional manner to Pi availability. Using the same system, whole-transcriptomic data from fungal hyphae unravelled the molecular basis of the EMF ability in Pi uptake at the global gene scale, revealing that EM symbiosis can directly affect Pi-responsive fungal genes such as the Pi transporter PiPT4. A second artificial system was used to study HAP solubilisation driven by P. involutus, which was confirmed by EDX spectroscopy data showing depletion of Pi from the HAP crystals, along with secondary minerals formation. Whole-transcriptomic analysis revealed that EM symbiosis induces a different set of HAP weathering genes in P. involutus hyphae, compared to the fungus growing non-symbiotically, including the specific expression of organic acid metabolic genes, which resulted in enhanced HAP solubilisation. Metabolomic analysis led to the identification of multiple secreted metabolites enriched in the presence of HAP in P. involutus systems grown non-symbiotically or in symbiosis with P. sylvestris seedlings. The analysis also led to the identification of putative novel fungal weathering agents. Results from transcriptomic and metabolomic analyses were ultimately combined in a model of HAP weathering by P. involutus.
Ključne besede: Paxillus involutus, Pinus sylvestris, ectomycorrhizal symbiosis, hydroxyapatite, SEM-EDX, fungal mineral weathering, fungal weathering metabolites, RNA-seq, UPLC-Q-TOF-MS
Objavljeno v RUNG: 03.05.2022; Ogledov: 1438; Prenosov: 0
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1295. The impact of temperature inversions on black carbon and particle mass concentrations in a mountainous areaKristina Glojek, Griša Močnik, Honey Dawn C. Alas, Andrea Cuesta-Mosquera, Luka Drinovec, Asta Gregorič, Matej Ogrin, Kay Weinhold, Irena Ježek, Martin Rigler, Maja Remškar, Miha Markelj, 2022, izvirni znanstveni članek Opis: Residential wood combustion is a widespread practice in Europe with a serious impact on air quality, especially in mountainous areas. While there is a significant number of studies conducted in deep urbanized valleys and basins, little is known about the air pollution processes in rural shallow hollows, where around 30 % of the people in mountainous areas across Europe live. We aim to determine the influence of ground temperature inversions on wood combustion aerosol pollution in hilly, rural areas. The study uses Retje karst hollow (Loški Potok, Slovenia) as a representative site for mountainous and hilly rural areas in central and south-eastern Europe with residential wood combustion. Sampling with a mobile monitoring platform along the hollow was performed in December 2017 and January 2018. The backpack mobile monitoring platform was used for the determination of equivalent black carbon (eBC) and particulate matter (PM) mass concentrations along the hollow. To ensure high quality of mobile measurement data, intercomparisons of mobile instruments with reference instruments were performed at two air quality stations during every run. Our study showed that aerosol pollution events in the relief depression were associated with high local emission intensities originating almost entirely from residential wood burning and shallow temperature inversions (58 m on average). The eBC and PM mass concentrations showed stronger associations with the potential temperature gradient (R2=0.8) than with any other meteorological parameters taken into account (ambient temperature, relative humidity, wind speed, wind direction, and precipitation). The strong association between the potential temperature gradient and pollutant concentrations suggests that even a small number of emission sources (total 243 households in the studied hollow) in similar hilly and mountainous rural areas with frequent temperature inversions can significantly increase the levels of eBC and PM and deteriorate local air quality. During temperature inversions the measured mean eBC and PM2.5 mass concentrations in the whole hollow were as high as 4.5±2.6 and 48.0 ± 27.7 µg m−3, respectively, which is comparable to larger European urban centres.
Ključne besede: air pollution, black carbon, sources, temperature inversion, mountainous area
Objavljeno v RUNG: 03.05.2022; Ogledov: 1355; Prenosov: 0
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