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Abstract: Functional genomics offers a powerful, unbiased approach to elucidating the molecular mechanisms underlying the toxicity of environmental pollutants. In this study, we applied genome-wide screening in Chlamydomonas reinhardtii to investigate two classical herbicides: paraquat and diuron. Our screen successfully uncovered critical nuclear-encoded pathways that govern susceptibility. For both herbicides, we identified genes regulating the assembly and maintenance of the photosynthetic machinery, highlighting the central role of nuclear control over these chloroplast-localized targets. Beyond these target-related factors, we discovered novel nontarget-site resistance mechanisms. For paraquat, we identified intracellular trafficking as the central determinant of toxicity, experimentally characterizing a P5B ATPase transporter and a fatty acid elongation pathway whose disruption, we propose, converges on the same endomembrane delivery route through sphingolipid depletion. In contrast, our screening data suggest that diuron tolerance may be associated with a metabolic strategy focused on energy conservation, where the inactivation of specific NADPH-consuming enzymes could preserve reducing power for essential antioxidant defense. Collectively, these findings demonstrate that functional genomics can reveal novel, complex modes of action even for well-characterized chemicals, providing the mechanistic resolution required to advance modern ecotoxicological risk assessments.
Keywords: paraquat, diuron
Published in DiRROS: 09.06.2026; Views: 321; Downloads: 369
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Keywords: potato virus Y, coat protein, viral movement, point mutations, Solanum tuberosum
Published in DiRROS: 31.03.2026; Views: 446; Downloads: 494
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Abstract: Potato virus Y (PVY) is one of the top 10 economically most important plant viruses and responsible for major yield losses. We previously suggested the involvement of the N-terminal region of PVY coat protein (CP) in PVY spread. By constructing different N-terminal deletion mutants of the PVY N605 strain, we here show that deletions of 40 or more amino acid residues from the N-terminal region of the CP resulted in the PVY multiplication limited to primary infected cells in Nicotiana clevelandii plants. Deletion of 26 residues profoundly impaired PVY cell-to-cell movement and prevented systemic PVY spread, while deletions of 19-23 residues allowed delayed systemic PVY spread. Introduced point mutations in the identified region prevent (S21G) or delay (G20P) PVY movement. In summary, this work shows the significance of the CP N-terminus for movement of the PVY.
Keywords: potato virus Y, potato, coat proteins, viral movement, point mutations
Published in DiRROS: 18.12.2025; Views: 1236; Downloads: 654
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Abstract: To investigate the dynamics of the potato – Potato virus Y (PVY) compatible interaction in relation to salicylic acid - controlled pathways we performed experiments using non-transgenic potato cv. Désirée, transgenic NahG-Désirée, cv. Igor and PVYNTN, the most aggressive strain of PVY. The importance of salicylic acid in viral multiplication and symptom development was confirmed by pronounced symptom development in NahG-Désirée, depleted in salicylic acid, and reversion of the effect after spraying with 2,6-dichloroisonicotinic acid (a salicylic acid - analogue). We have employed quantitative PCR for monitoring virus multiplication, as well as plant responses through expression of selected marker genes of photosynthetic activity, carbohydrate metabolism and the defence response. Viral multiplication was the slowest in inoculated potato of cv. Désirée, the only asymptomatic genotype in the study. The intensity of defence-related gene expression was much stronger in both sensitive genotypes (NahG-Désirée and cv. Igor) at the site of inoculation than in asymptomatic plants (cv. Désirée). Photosynthesis and carbohydrate metabolism gene expression differed between the symptomatic and asymptomatic phenotypes. The differential gene expression pattern of the two sensitive genotypes indicates that the outcome of the interaction does not rely simply on one regulatory component, but similar phenotypical features can result from distinct responses at the molecular level.
Keywords: plant viruses, plant diseases
Published in DiRROS: 04.03.2025; Views: 1177; Downloads: 713
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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: 1640; Downloads: 1543
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