TY - CONF AU - Francis, Michel AU - Müller, Brigitta AU - Gracheva, Maria AU - Sági-Kazár, Máté AU - Solymosi, Katalin AU - Colocho, Hurtarte Luis Carlos AU - Castillo-Michel, Hiram AU - Pongrac, Paula AU - Vogel-Mikuš, Katarina AU - Bonanni, Valentina AU - Žižić, Milan AU - Gianoncelli, Alexandra AU - Solti, Ádám TI - The impact of nitric oxide signal on the intracellular iron distribution T2 - Plant Biology Europe 2025 SN - 9786156833020 PY - 2025 SP - O-105 UR - https://m2.mtmt.hu/api/publication/36322372 ID - 36322372 AB - The photosynthetic apparatus requires the incorporation of a significant amount of transition metal cofactors, among others Fe containing FeS clusters and heme groups. Despite the importance of Fe loading into chloroplasts, transition metal allocation in cells is not a unidirectional process, since eukaryotic cells perform a dynamic structural reorganisation in order to adapt to the challenges of the environment. Nevertheless, the control over Fe allocation to the cell compartment in the mesophyll remained poorly known. Since nitric oxide (NO) has been found to be an important factor in the coordination of the root Fe uptake and homeostasis, its role in the mesophyll cell Fe homeostasis is also proposed. Cryosectioned mesophyll cells of early senescent Arabidopsis thaliana lines affected in the NO homeostasis by defects of NO biosynthesis (noa1) and affected in the S-nitrosoglutathione reductase enzyme (GSNOR, deficient and overexpressing) were to particle induced X-ray emission (μPIXE), low energy X-ray fluorescence microscopy (LEXRF), and high energy (HE) XRF microscopy. The HEXRF dataset is accessible at Solti et al. (2025). K-means clustering of the Fe signal distribution approved that perturbed NO signaling resulted in a lowered plastidial Fe allocation in the early senescent stage that underlines impact and the pro-senescence property of the NO signaling nature on the plastidial Fe accumulation. Reference Solti Á & al. (2025). ESRF. doi.org/10.15151/ESRF-ES-790328283 [Dataset]. This work was supported by the grant K-135607 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities under proposal number LS-3039. Instrument center access was financed under ReMade@ARI PID 34653 (financed as part of HORIZON-INFRA-2021-SERV-01, 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste, Italy for the beam time access (20245567). LA - English DB - MTMT ER - TY - CONF AU - Müller, Brigitta AU - Francis, Michel AU - Pongrac, Paula AU - Vogel-Mikuš, Katarina AU - Bonanni, Valentina AU - Žižić, Milan AU - Gianoncelli, Alexandra AU - Thomine, Sébastien AU - Solti, Ádám TI - Regulation effect of PH domain containing proteins on Mn transport and distribution T2 - Plant Biology Europe 2025 SN - 9786156833020 PY - 2025 SP - O-108 UR - https://m2.mtmt.hu/api/publication/36322415 ID - 36322415 AB - Manganese (Mn) is essential for various plant processes, including lignin biosynthesis, cell wall formation, and enzyme activities, among others the function of the water splitting complex in photosystem II of the thylakoid membranes of chloroplasts. Although Mn homeostasis plays a pivotal role in plant cells, the regulation of Mn distribution at the cellular level is still poorly understood. Mn transporters in the plant membranes, among others NATURAL RESISTANCE-ASSOCIATED MACROPHAGE PROTEIN 1 (NRAMP1) channel the Mn content of the cell towards the site of incorporation to enzyme proteins. Localization of NRAMP1 is regulated by PH DOMAIN CONTAINING 1 (PH1), determining the trafficking of NRAMP1. Unlike PH1, the role of PH2 in Mn transport remained unclear. Applying Arabidopsis thaliana ph1ph2 double mutant lacking functional PH1 and PH2 proteins, we aimed to explore whether PH2 influences NRAMP1 localization and, consequently, Mn allocation in plant cells, and whether PH proteins are responsible for pleiotropic effects in Mn distribution. On cryosectioned, lyophilized samples we employed particle induced X-ray fluorescence microscopy (µPIXE) and low-energy X-ray fluorescence (LEXRF) microspectroscopy to map Mn distribution at tissue and cell levels, respectively. Comparing wild type and ph1ph2 lines grown under Mn containing and Mn deprived conditions, ph1ph2 line indicated a perturbed plastidial Mn accumulation resulted in a failures to respond the altered Mn nutrition. Along with the altered Mn distribution, we also observed minor shifts in the Fe distribution within the cells, with a noticeable shift towards the plastids. This work was supported by the grant K-146865 of NKFIH, Hungary, and by the Bilateral Research Agreement of Centre National de la Recherche Scientifique and Hungarian Academy of Sciences (HAS). Á.S. was supported by the János Bolyai Scholarship of HAS (BO-00113-23-8). Instrument center access was financed under ReMade@ARI PID 34653 (financed as part of HORIZON-INFRA-2021-SERV-01, agreement No. 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste, Italy for the beam time access (20245567). LA - English DB - MTMT ER - TY - CONF AU - Radics, Nóra AU - Gracheva, Maria AU - Marzougui, Linda AU - Putra, Budi AU - Kovács, Veronika AU - Francis, Michel AU - Sági-Kazár, Máté AU - Müller, Brigitta AU - Solti, Ádám TI - Exploring essential and contaminant distribution in plants: X-ray fluorescence imaging T2 - Plant Biology Europe 2025 SN - 9786156833020 PY - 2025 SP - P-223 UR - https://m2.mtmt.hu/api/publication/36322421 ID - 36322421 AB - Concentrations of essential heavy metals, like all environmental factors, have to be kept within an optimal range to avoid plant stress. Low concentrations may induce deficiency, whereas toxicity arise at high concentrations. Non-essential metals might be toxic as well. The control over their distribution in plant tissues is vital to avoid both deficiency of essential elements, and accumulation induced toxicity. Thus, understanding lateral distribution, compartmentalization, that support the understanding of the underlying transport processes has a prime importance. X-ray fluorescence (XRF) imaging is a powerful non-destructive technique that provides high-resolution elemental maps of flat surfaces such as leaves, enabling the visualization of Fe distribution at organ, and tissues levels. In the current study we applied a Horiba XGT-7200 desktop imaging system for the study of organ-level distributions of essential macro- and microelements. The system enables to reach resolutions down to 2 μm pixel width, depending on the resolution and area settings (Gracheva et al. 2022). However, signal intensity obtained from the K emission of essential and trace elements generally does not support the imaging of their distribution. Indeed, obtained X-ray fluorescence still bear valuable information. Accurate data handling is critical for precise interpretation, and strategies for minimizing artifacts, optimizing signal-to-noise ratios, and employing advanced image analysis methods must be used to generate qualitative and semi-quantitative distribution profiles. XRF-based techniques are versatile and can be used to study diverse plant species, providing a comprehensive understanding of Fe metabolism throughout the plant kingdom. We have tested multiple plant models, including Arabidopsis thaliana, Triticum aestivum, and Ginkgo biloba to how essential and non-essential metals can be detected. Using elemental profiling by comparing the natural distribution of essential and trace elements, we can identify potential interactions and co-localization patterns for a deeper understanding of plant physiology. We highlight the key role of XRF imaging and careful data handling in advancing knowledge of essential and trace metals in plants. This knowledge could be used to address of tolerance to environmental stresses. Reference Gracheva et al. (2022). Photochem. Photobiol. Sci. 21: 983. This work was supported by the grant K-146865 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). XRF imaging facility was granted by the European Structural and Investment Funds (VEKOP-2.3.3-15-2016-00008). LA - English DB - MTMT ER - TY - CONF AU - Marzougui, Linda AU - Krett, Gergely AU - M Tóth, Erika AU - Solti, Ádám TI - Phytotoxicity of two crystalline forms of titanium dioxide nanoparticles T2 - Plant Biology Europe 2025 SN - 9786156833020 PY - 2025 SP - P-149 UR - https://m2.mtmt.hu/api/publication/36322430 ID - 36322430 AB - Nano scale particles are receiving increasing attention worldwide due to the properties that might be fundamentally distinct of dissolved materials or microscopic particles for many applications. Nano scale particles are characterized by size ranging from 1 to 100 nm extent at least in one dimension. Nano scale particles of titanium dioxide (nTiO₂) are becoming more prevalent in the environment as a consequence of their large-scale industrial utilization. The nTiO₂ particles are known in two crystalline form: rutil and anatase, where rutile is a nanoparticle in two dimensions, whereas anatase is in all three dimensions. Although the European Food Safety Authority (EFSA) has updated the safety assessment of titanium dioxide (E 171) in the past years that nTiO₂ as a food additive colourant is not considered being safe. In spite, data are scarce on the environmentel effect and phytotoxicity of nTiO₂ crystalline forms. This study aims to evaluate the potential phytotoxicity of TiO₂ nanoparticles specifically the anatase and rutile crystalline form, on bread wheat (Triticum aestivum). Since accumulation of nTiO₂ particles in a high density means an additional risk, we were also aimed to model the effect of accumulation. Manufactured nTiO₂ particles (anatase and rutile; NTA-20-S25-01 and NTR-20-02, respectively) were applied on wheat seedlings at three leaves stage in a concentration range from 50 to 3000 ppm. Experiments were performed in hydroponics as short (1-2 days) and long term (14 days) exposure. Physiological responses: status of the photosynthetic apparatus, malondialdehyde (MDA) content, activity of antioxidative enzymes (ascorbate peroxidase activity; catalase) were analyzed together with element mapping by X-ray fluorescence (XRF) imaging. Data emphasize that anatase was nottoxic, while rutile showed toxic effects only at higher concentrations, connected with the increase in the Ti-Kα XFR signal. Importantly, high MDA levels and reduced photosynthetic efficiency were shown under high rutile exposure, pointing to oxidative damage and reduced photosynthetic efficiency. These outcomes illustrate the need to differentiate between nanoparticle types in assessing environmental impacts. Follow-up studies can highlight the ecological impacts of nTiO₂ particles through the investigation of long-term exposure effects linked to those nanoparticles, molecular responses, and soil-plant interactions. This work was supported by the grant K-135607 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). XRF imaging facility was granted by the European Structural and Investment Funds (VEKOP-2.3.3-15-2016-00008). We kindly thank the technical support of Sándorné Pardi LA - English DB - MTMT ER - TY - CONF AU - Putra, Budi AU - Petrovicz, Lili AU - Müller, Brigitta AU - Francis, Michel AU - Sági-Kazár, Máté AU - Gracheva, Maria AU - Bonanni, Valentina AU - Žižić, Milan AU - Gianoncelli, Alexandra AU - Pongrac, Paula AU - Vogel-Mikuš, Katarina AU - Solti, Ádám ED - Connolly, Erin ED - Bartnikas, Tom TI - The role of the ATG7 mediated autophagy pathway in the plastidial Fe homeostasis T2 - Cell Biology of Metals - Gordon Research Conference 2025 PY - 2025 SP - P29 UR - https://m2.mtmt.hu/api/publication/36322459 ID - 36322459 AB - Iron (Fe) is an essential metal cofactor. Since the operation of the photosynthetic electron transport chain of plants relies on Fe containing cofactors, chloroplasts are primary sites of Fe allocation in the mesophyll cells performing photosynthesis. Although the Fe uptake into chloroplasts and the incorporation of Fe into cofactors of photosynthesis has been extensively studied in the past decades, pieces of information how essential metals, among others Fe is removed from these incorporation sites. Among the few pieces of information on the removal of plastidial Fe, results of Pottier et al. (2019; DOI: 10.1093/jxb/ery388) indicated that autophagosome dependent chloroplast degradation is crucial in the process. Autophagy related Gene 7 protein (ATG7) is an E1-like enzyme that takes part both in the first and second conjugation system, conjugating phosphatidylethanolamine to ATG8 and ATG5 to ATG12, respectively that are fundamental steps in autophagosome formation. ATG7 is encoded by a single gene (At5g45900) in the Arabidopsis genome. Since cargo recruitment is based on receptors interact with ATG8, ATG7 is an upstream element that also impacts the size of the autophagosome. Two Col-0 based T-DNA insertion lines, atg7.1 and atg7.2 were involved to the current analysis. Mature rosette leaves at flowering initiation were samples. By physiological performance and chloroplast Fe content, the leaves of ATG7 affected lines segregated from that of the Col-0 plants, were Fe content in the chloroplasts of ATG7 affected lines was significantly higher. In contrast, Fe content in the chloroplasts of Col-0 leaves negatively correlated to the senescence status. Accumulation of Fe was also confirmed by X-ray fluorescence emission (PIXE) mapping, and low energy X-ray fluorescence (LEXRF) on cryosectioned samples. In ATG7 affected lines the relative transcript abundance of Atg7 drastically increased whereas in Col-0, it correlated positively to the senescence status. In ATG7 affected lines, relative transcript abundance of Atg5 also increased, in function of the senescence status. Thus we confirm that the pathway in ATG7 function as upstream element is a key mechanism in the removal of Fe from chloroplasts. This work was supported by the grant K-146865 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). Instrument center access was financed under ReMade@ARI PIDs 27548 & 34653 (financed as part of HORIZON-INFRA-2021-SERV-01, 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste, Italy for the beam time accesses (20235332 & 20245567). LA - English DB - MTMT ER - TY - CONF AU - Müller, Brigitta AU - Francis, Michel AU - Gracheva, Maria AU - Petrovecz, Lili AU - Putra, Budi AU - Bonanni, Valentina AU - Gianoncelli, Alexandra AU - Pongrac, Paula AU - Vogel-Mikuš, Katarina AU - Solti, Ádám ED - Connolly, Erin ED - Bartnikas, Tom TI - S-nitrosoglutathione reductase activity modulates the plastidial iron homeostasis in Arabidopsis thaliana T2 - Cell Biology of Metals - Gordon Research Conference 2025 PY - 2025 SP - P40 UR - https://m2.mtmt.hu/api/publication/36322471 ID - 36322471 AB - Photosynthesis requires the incorporation of iron (Fe) into enzyme complexes. Nitric oxide (NO) is confirmed to impact the Fe homeostasis of mesophyll cells. High expression of the NO production elements precedes developmental senescence, and plastidial NO production is enhanced under Fe limited conditions. Nevertheless, the role of NO induced regulation in plastidial Fe homeostasis remained poorly known. S-nitrosoglutathione (GSNO) is a key transmitter of NO signal that is eliminated by GSNO reductase (GSNOR). Cryosectioned mesophyll cells of early senescent Arabidopsis thaliana line leaves affected in GSNOR (deficient: gsnor1-3; and overexpressing: 35::FLAG::GSNOR) and in NO biosynthesis (noa1) were analysed using particle induced X-ray emission (μPIXE), and low energy X-ray fluorescence microscopy (LEXRF). K-means clustering of the Fe signal distribution revealed that perturbed both GSNOR overexpression and its defect resulted in a lowered plastidial Fe accumulation in the early senescent stage, also confirmed by the Fe content of isolated chloroplasts and the lowered expression of plastidial Fe acquisition elements indicating that NO signaling has a dose dependent, Janus-faced impact on the plastidial Fe accumulation. This work was supported by the grant K-135607 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). Instrument center access was financed under ReMade@ARI PID 34653 (financed as part of HORIZON-INFRA-2021-SERV-01, 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste, Italy for the beam time access (20245567). LA - English DB - MTMT ER - TY - CONF AU - Francis, Michel AU - Gracheva, Maria AU - Sági-Kazár, Máté AU - Solymosi, Katalin AU - Colocho, Hurtarte Luis Carlos AU - Castillo-Michel, Hiram AU - Solti, Ádám ED - Küpper, H TI - Unraveling the role nitric oxide in plastidial iron allocation using bioinfirmatics and multielement clustering T2 - Book of Abstracts PLANTMETALS - TRACE METAL METABOLISM IN PLANTS Conference 2025 PY - 2025 SP - 16 UR - https://m2.mtmt.hu/api/publication/36332642 ID - 36332642 AB - Understanding essential transition metal allocation in plants cells is pivotal to decode metal homeostasis in organelles. In that revealing microscopy X-Ray Fluorescence (μXRF) is a powerful technique, yet indeed generates a massive amount of data, requiring appropriate bioinformatics in dataset handling. To understand intracellular Fe allocation in nitric oxide signaling and autophagy compromised Arabidopsis thaliana mesophyll cells, we applied 20 μm thick cryosection samples. Dataset on the K edge signal of transition metal distribution were gained at ID21, European Synchrotron Radiation Facility, and analyzed using two computational approaches. First, sample was analyzed as composed of foreground and background layers, differentiated by intensity thresholds computing, and morphological operations were applied to improve the clarity of segmented regions. Focusing on background layer, away from organelles overlapping or noise, provided detailed structural interpretation of Fe-rich zones. The second approach applied k-means clustering, treating each pixel as a point in multidimensional element space, where each organelle occupied a distinct region in this space region based on its characteristic elemental composition and corresponding to its specific functions. Both approaches independently indicated that compromised lines show altered plastidial Fe allocation at senescence initiation. This agreement increases the confidence in the biological findings and in the robustness of each method. This work was supported by the grant K-146865 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities under proposal number LS-3039. LA - English DB - MTMT ER - TY - CONF AU - Müller, Brigitta AU - Gracheva, Maria AU - Sági-Kazár, Máté AU - Francis, Michel AU - Bonanni, Valentina AU - Žižić, Milan AU - Gianoncelli, Alexandra AU - Pongrac, Paula AU - Kelemen, Mitja AU - Vogel-Mikuš, Katarina AU - Solti, Ádám ED - Küpper, H TI - Is the way of Fe removal from chloroplasts a form of ferritinophagy? T2 - Book of Abstracts PLANTMETALS - TRACE METAL METABOLISM IN PLANTS Conference 2025 PY - 2025 SP - 58 UR - https://m2.mtmt.hu/api/publication/36332646 ID - 36332646 AB - Autophagy is essential in the turnover of cell components. In animals, ferritinophagy, targeting ferritins an important way for intracellular iron mobilization. In plants, ferritins are targeting chloroplasts and mitochondria, whereas the majority of cellular iron is found in chloroplasts. Little is known, however, on the iron recycling from chloroplasts. Accumulation of ferritins under developmental senescence has been long described, the connection between ferritins and iron remobilization has not been fully revealed. In Arabidopsis thaliana Col-0 leaves iron content of chloroplasts, and the iron peak at plastidial loci gained by low energy X-ray fluorescence microscopy (LEXRF) indicated strong coincidences: a peak accumulation occurred at early senescence that disappeared in later stages. Appearance of ferritins is, however, a rare event found exclusively at early senescence. Expression and protein amount of of FERs also indicated the same pattern. In autophagosome defective (atg5.2, atg7.2, ati1) lines, iron accumulation was revealed at plastidial locations associated increased plastidial Fe content, FER expression and protein amount. Although we have no data on any co-localization of ferritins to autophagosomes, data at the current stage suggest that ferritinophagy might be the way of iron recycling from plastids during developmental senescence. This work was supported by the grant K-146865 of NKFIH, Hungary. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). Instrument center access was financed under ReMade@ARI PIDs 27548 & 34653 (financed as part of HORIZON-INFRA-2021-SERV- 01, 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste, Italy for the beam time accesses (20235332 & 20245567). LA - English DB - MTMT ER - TY - DATA AU - Solti, Ádám AU - Solymosi, K AU - Gracheva, Maria AU - Sági-Kazár, M TI - Senescence and iron release from plastids: ways of iron remodelling [Dataset] PY - 2025 DO - 10.15151/ESRF-ES-790328283 UR - https://m2.mtmt.hu/api/publication/36337818 ID - 36337818 AB - Iron (Fe) is essential cofactor in various physiological processes such as the operation of the photosynthetic functions. In Planta, Fe content of leaves also serves as Fe source during senescence processes. Retranslocation of Fe is connected to the alteration in the regulation of chloroplast Fe homeostasis. Our data (Pham et al, 2020, Sági-Kazár et al, under peer-review) indicate that regulation of the chloroplast Fe homeostasis and senescence processes are in a close interaction. The understanding they way and reasons of Fe remodelling may provide a basis for the development of better foliar Fe application and biofortification techniques. With the help of single point μXANES we could determine any possible chemical modifications in the Fe content of chloroplasts as well as that of mesophyll cells in the areas of interest. Data are essential for the proper interpretation of ou molecular biological information. LA - English DB - MTMT ER - TY - CONF AU - Keresztes, Á AU - Müller, B AU - Sárvári, Éva AU - Nyitrai, P AU - Pham, H-D AU - Mihailova, G AU - Szalai, G AU - Sas, L AU - Georgieva, K AU - Vass, I AU - Solti, Ádám TI - Mitophagy in resurrection plant Haberlea rhodopensis: Vacuolar intrusion of mitochondria responds to chilling stress T2 - Book of Abstracts - 1st First International Conference on Functional Biology PY - 2025 SP - OP–07 UR - https://m2.mtmt.hu/api/publication/36340368 ID - 36340368 AB - Haberlea rhodopensis is a homoiochlorophyllous resurrection plant with remarkable tolerance to both desiccation and sub-zero temperatures. While the overlap between drought and freezing tolerance has been previously established, specific mitochondrial responses to chilling stress remained poorly understood. This study elucidates the chilling tolerance mechanisms of H. rhodopensis, focusing on mitochondrial behaviour and alternative oxidase (AOX)-mediated respiration. Under chilling conditions (above-freezing low temperatures), HrAOX2 transcript abundance, AOX protein levels and AOX-dependent respiration significantly increased—up to four-fold—compared to control plants. This shift in mitochondrial activity occurred alongside localized warming in the leaves, as detected by thermal imaging, suggesting that AOX activity contributes to cellular heat generation even in non-thermogenic plant tissues. Crucially, ultrastructural analysis revealed the unusual relocation of mitochondria into the central vacuole, where they appeared to undergo a slow and spatially controlled degradation process. This "delayed mitophagy" likely enables mitochondria to maintain AOX activity and contribute to thermogenesis and redox homeostasis before their eventual breakdown. The vacuolar sequestration of mitochondria may also protect the cytoplasm from excessive reactive oxygen species production during stress. Upon prolonged exposure or sub-zero temperatures, these mitochondria disintegrated, correlating with reduced AOX activity and loss of thermal buffering capacity. Our findings reveal a sophisticated, multi-level adaptive strategy in H. rhodopensis, where coordinated AOX-driven respiration and regulated mitophagy support metabolic stability and thermal protection during chilling stress. This mechanism likely co-evolved with desiccation tolerance and may inform future approaches for improving cold resilience in crop species under climate change. Keywords: Haberlea rhodopensis; mitophagy; alternative oxidase; thermogenesis, chilling stress Acknowledgements: This work was supported by the grant K-146865 of NKFIH, Hungary, and by the bilateral mobility grant between the Hungarian and the Bulgarian Academies of Sciences. Á.S. was supported by the János Bolyai Scholarship of the Hungarian Academy of Sciences under grant number BO-00113-23-8. LA - English DB - MTMT ER -