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Abstract: Ethylene response factors (ERFs) have been associated with biotic stress in Arabidopsis, while their function in non-model plants is still poorly understood. Here we investigated the role of potato ERF StPti5 in plant immunity. We show that StPti5 acts as a susceptibility factor. It negatively regulates potato immunity against potato virus Y and Ralstonia solanacearum, pathogens with completely different modes of action, and thereby has a different role than its orthologue in tomato. Remarkably, StPti5 is destabilised in healthy plants via the autophagy pathway and accumulates exclusively in the nucleus upon infection. We demonstrate that StEIN3 and StEIL1 directly bind the StPti5 promoter and activate its expression, while synergistic activity of the ethylene and salicylic acid pathways is required for regulated StPti expression. To gain further insight into the mode of StPti5 action in attenuating potato defence responses, we investigated transcriptional changes in salicylic acid deficient potato lines with silenced StPti5 expression. We show that StPti5 regulates the expression of other ERFs and downregulates the ubiquitin-proteasome pathway as well as several proteases involved in directed proteolysis. This study adds a novel element to the complex puzzle of immune regulation, by deciphering a two-level regulation of ERF transcription factor activity in response to pathogens.
Keywords: ethylene response factor, immune signalling, potato virus Y, Pti5, Ralstonia solanacearum, Solanum tuberosum, susceptibility factor
Published in DiRROS: 29.08.2024; Views: 323; Downloads: 705
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Abstract: Rivers are spatially and temporally heterogeneous systems that are susceptible to changes due to anthropogenic influences. These can significantly alter water quality and river communities, including macrophytes, which are involved in nutrient cycling, energy flow and sedimentation processes, and provide habitats for other organisms. The presence, abundance, and distribution of macrophytes can thus serve as indicators of the state of aquatic ecosystems. Rivers that flow (partially) underground are particularly susceptible to (human) impacts from the hinterland due to their lower self-purification capacity. Using a modified RCE (a Riparian, Channel, and Environmental Inventory) method, we classified the Rak River as first or second RCE quality class, and the Obrh River as second or third RCE quality class. According to the River Macrophyte Index (RMI), the ecological status of both rivers was moderate, good or very good, except for the first section of the Obrh, the status of which was assessed as poor. The ecomorphological preservation of both rivers and suitable conditions for macrophyte growth contribute to the high species diversity observed in both rivers: a total of 36 taxa were recorded in the Obrh and 38 in the Rak. In the latter, the presence of Myriophyllum verticillatum L. was recorded for the first time at the time of our sampling. Almost one third of the species in each of the rivers are listed on the Slovenian Red list of threatened pteridophytes and seed plants, supporting the evidence of their high naturalness and emphasizing the importance of appropriate management of karst watercourses.
Keywords: karst, macrophytes, RCE method
Published in DiRROS: 29.08.2024; Views: 301; Downloads: 237
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Abstract: Aim: Marginal tree populations, either those located at the edges of the species' rangeor in suboptimal environments, are often a valuable genetic resource for biologicalconservation. However, there is a lack of knowledge about the genetic consequencesof population marginality, estimated across entire species' ranges. Our study ad-dresses this gap by providing information about several genetic indicators and theirvariability in marginal and core populations identified using quantitative marginalityindices.Location: Southwestern Europe and North Africa.Methods: Using 10,185 SNPs across 82 populations of maritime pine (Pinus pinasterAit.), a widespread conifer characterised by a fragmented range, we modelled therelationship of seven genetic indicators potentially related to population evolution-ary resilience, namely genetic diversity (based on both all SNPs and outlier SNPs),inbreeding, genetic differentiation, recessive genetic load and genomic offset, withpopulation geographical, demo-historical and ecological marginality (as estimated bynine quantitative indices). Models were constructed for both regional (introducinggene pool as a random factor) and range-wide spatial scales.Results: We showed a trend towards decreasing overall genetic diversity and increas-ing differentiation with geographic marginality, supporting the centre-periphery hy-pothesis (CPH). However, we found no correlation between population inbreedingand marginality, while geographically marginal populations had a lower recessive ge-netic load (only models without the gene pool effect). Ecologically marginal popula-tions had a higher genomic offset, suggesting higher maladaptation to future climate,albeit some of these populations also had high genetic diversity for climate outliers.Main Conclusions: Overall genetic diversity (but not outlier-based estimates) and dif-ferentiation patterns support the CPH. Ecologically marginal populations and those atthe southern edge could be more vulnerable to climate change due to higher climate maladaptation, as predicted by genomic offsets, and/or lower potentially adaptive ge-netic diversity. This risk is exacerbated by typically small effective population sizesand increasing human impact in marginal populations.
Keywords: population genetics, conservation genetics, marginal populations, Pinus pinaster, genetic indicators
Published in DiRROS: 29.08.2024; Views: 327; Downloads: 516
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Abstract: The systemic toxicity of cyclic peptides produced by cyanobacteria (CCPs) is not yet completely understood. Apart from the most known damages to the liver and kidneys, symptoms of their neurotoxicity have also been reported. Hepatotoxic CCPs, like microcystins, as well as non-hepatotoxic anabaenopeptins and planktopeptins, all exhibit cytotoxic and cytostatic effects on mammalian cells. However, responses of different cell types to CCPs depend on their specific modes of interaction with cell membranes. This study demonstrates that non-hepatotoxic planktopeptin BL1125 and anabaenopeptins B and F, at concentrations up to 10 µM, affect normal and tumor human astrocytes (NHA and U87-GM) in vitro by their almost immediate insertion into the lipid monolayer. Like microcystin-LR (up to 1 µM), they inhibit Ser/Thr phosphatases and reorganize cytoskeletal elements, with modest effects on their gene expression. Based on the observed effects on intermediate filaments and intermediate filament linkage elements, their direct or indirect influence on tubulin cytoskeletons via post-translational modifications, we conclude that the basic mechanism of CCP toxicities is the induction of inter- and intracellular communication failure. The assessed inhibitory activity on Ser/Thr phosphatases is also crucial since the signal transduction cascades are modulated by phosphorylation/dephosphorylation processes.
Keywords: astrocytes, cyclic cyanobacterial peptides, cytoskeletal organization, Ser/Thr phosphatases, systemic toxicity, cyanobacteria
Published in DiRROS: 28.08.2024; Views: 416; Downloads: 361
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Published in DiRROS: 28.08.2024; Views: 321; Downloads: 449
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