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1.
Phosphate availability and ectomycorrhizal symbiosis with Pinus sylvestris have independent effects on the Paxillus involutus transcriptome
Stephen A. Rolfe, Jonathan R. Leake, David J. Beerling, Christina Paparokidou, 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.
Najdeno v: osebi
Ključne besede: Ectomycorrhizal symbiosis, Paxillus involutus, Pi transporters, Pi-starvation, Pinus sylvestris, RNA-seq.
Objavljeno: 03.05.2022; Ogledov: 270; Prenosov: 0
.pdf Polno besedilo (1,37 MB)

2.
Unraveling the Role of Major Facilitator Superfamily (MFS) Transporters in Plant Abiotic Stress Tolerance
Christina Paparokidou, 2014, končno poročilo o rezultatih raziskav

Opis: The yields of worldwide crop production are negatively affected by adverse environmental conditions, such as drought, salinity, heavy metal contamination and nutrient depletion in cultivated soils (Yan et al., 2013; Golldack et al., 2011; Yadav, 2010; Kobayashi and Nishizawa, 2012). This reduced crop production constitutes a major problem for food sustainability world-wide (Spiertz, 2013). Indeed, one of the major challenges for plant biotechnology will be to satisfy the increased demand for food on one hand, and to compensate for the loss of crop production on the other. Thus, the discovery of new plant genes that are able to cope with these conditions is critical and expected not only to elucidate the molecular mechanisms underlying crop abiotic stress, but also to pioneer genetic engineering strategies for improved crop productivity. The goal of this project was to identify novel genes belonging to the Major Facilitator Superfamily (MFS) of plant membrane transporters with potential major roles in conferring abiotic stress tolerance, namely to heavy metal, osmotic and iron deficiency stress. We selected three Arabidopsis thaliana MFS transporter genes, provisionally called MFS10, MFS11 and MFS12, which based on publicly available microarray data display specific expression patterns suggesting roles in plant tolerance to different abiotic stresses. RT-PCR analyses showed that in fact the MFS10 gene is highly induced by cadmium (Cd), selenium (Se), salt and mannitol, while the MFS11 gene is upregulated by abscisic acid (ABA) and glucose, and the MFS12 gene by iron (Fe) deficiency, ABA and glucose. Furthermore, subcellular localization of fluorescent reporter fusions indicated that the MFS10 and MFS11 gene products are both plasma membrane localized transporters, while the encoded product of the MFS12 gene appears to be an endoplasmic reticulum localized transporter. Finally, reverse genetics using a null mutant allele for the MFS10 gene demonstrated that it functions as a regulator of plant responses to hyperosmotic (drought and salt) stress.
Najdeno v: osebi
Ključne besede: Major Facilitator Superfamily (MFS), abiotic stress tolerance, heavy metals, osmotic stress, ABA stress, iron deficiency, T-DNA insertion lines, RT-PCR, confocal microscopy.
Objavljeno: 03.05.2022; Ogledov: 284; Prenosov: 0
.pdf Polno besedilo (1,54 MB)

3.
Abscisic acid-regulated water channels and their role in plant acclimation and tolerance to water stress
Christina 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).
Najdeno v: osebi
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
Objavljeno: 03.05.2022; Ogledov: 275; Prenosov: 0
.pdf Polno besedilo (1,06 MB)

4.
Identification of putative anthocyanin transporters in Petunia hybrida
Christina Paparokidou, 2013, končno poročilo o rezultatih raziskav

Najdeno v: osebi
Ključne besede: knock out transposon-generated mutants, dTPH1 transposable element, MATE family, MRP transporters, RT-PCR, confocal microscopy.
Objavljeno: 03.05.2022; Ogledov: 277; Prenosov: 0
.pdf Polno besedilo (4,62 MB)

5.
Unravelling the molecular basis of hydroxyapatite weathering driven by the ectomycorrhizal fungus Paxillus involutus
Christina 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.
Najdeno v: osebi
Ključne besede: Paxillus involutus, Pinus sylvestris, ectomycorrhizal symbiosis, hydroxyapatite, SEM-EDX, fungal mineral weathering, fungal weathering metabolites, RNA-seq, UPLC-Q-TOF-MS
Objavljeno: 03.05.2022; Ogledov: 249; Prenosov: 0
.pdf Polno besedilo (33,58 MB)

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