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Magnesium (Mg) is the ubiquitous metal ion present in chlorophyll and bacteriochlorophyll (BChl), involved in photosystems in photosynthetic organisms. In the present study we investigated targets of toxic copper binding to the photosynthetic apparatus of the anoxygenic purple bacterium Rhodospirillum rubrum. This was done by a combination of in vivo measurements of flash photolysis and fast fluorescence kinetics combined with the analysis of metal binding to pigments and pigment-protein complexes isolated from Cu-stressed cells by HPLC-ICPMS (ICP-sfMS). This work concludes that R. rubrum is highly sensitive to Cu, with a strong inhibition of the photosynthetic reaction centres (RCs) already at 2 μM Cu. The inhibition of growth and of RC activity was related to the formation of Cu-containing BChl degradation products that occurred much more in the RC than in LH1. These results suggest that the shift of metal centres in BChl from Mg to Cu can occur in vivo in the RCs of R. rubrum under environmentally realistic Cu concentrations, leading to a strong inhibition of the function of these RCs.
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http://dx.doi.org/10.1016/j.bbabio.2019.06.004 | DOI Listing |
bioRxiv
August 2025
Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Chloroplasts play a central role in plant responses to environmental stress. Little is known, however, about how chloroplast homeostasis is maintained during stress responses that place high metabolic and bioenergetic demands on the cell. As a chloroplast-derived retrograde signal, jasmonate (JA) promotes broad-spectrum immunity by triggering the degradation of JAZ transcriptional repressors that act in the nucleus to control chloroplast metabolism.
View Article and Find Full Text PDFPlant J
September 2025
Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas (CSIC), Seville, 41012, Spain.
Despite being an essential micronutrient and its recent classification as a beneficial macronutrient, chloride (Cl) has traditionally been considered of limited agricultural relevance and a potentially toxic saline ion. This study provides the first comprehensive demonstration of the quantitative and qualitative importance of Cl during early vegetative development (EVD) of tobacco and Arabidopsis thaliana plants. During this developmental stage, these and other species (including celery, lettuce, Swiss chard, spinach, squash, tomato, chili pepper, eggplant, and perennial ryegrass) exhibit the highest demand and transport rate of this non-assimilable mineral nutrient to maximise growth of these herbaceous and also woody (such as citrus and olive) species.
View Article and Find Full Text PDFPlants (Basel)
August 2025
Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University in Poznań, ul Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland.
High light intensity constitutes a critical abiotic stress factor that profoundly affects the structural and functional integrity of the photosynthetic apparatus. Excessive irradiance triggers accelerated degradation of the PsbA polypeptide, increases susceptibility to photoinhibition, and promotes overproduction of reactive oxygen species (ROS), thereby inducing oxidative damage to proteins, lipids, and nucleic acids. Among the chloroplast-localized site-2 proteases of , remains the least characterized.
View Article and Find Full Text PDFFront Plant Sci
August 2025
National Key Laboratory of Clean Coal Grading Conservation, Shaaxi Coal and Chemical Industry Group Co., Xi'an, China.
Understanding plants responses to drought stress is crucial for selecting appropriate species for shelter-forest construction in arid and semi-arid regions. , one of the most planted shrubs along the Taklimakan Desert Highway Shelterbelt (TDHS), contributes significantly to maintaining the highway's ecological stability. This study aimed to investigate the physiological responses of biennial seedlings to drought stress by monitoring changes in soil moisture and chlorophyll fluorescence parameters [actual photo chemical efficiency of PSII (Y), unregulated energy dissipation quantum yield (Y), non-photochemical quenching coefficient (NPQ), and regulatory energy dissipation quantum yield (Y] under controlled conditions.
View Article and Find Full Text PDFJ Environ Sci (China)
December 2025
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
The sensitivity of phytoplankton growth to chemical stressors influences the composition and function of phytoplankton communities. In this study, we compared the growth, photosynthetic, and metabolic responses of the cyanobacterium Microcystis aeruginosa FACHB-469 and the green alga Raphidocelis subcapitata FACHB-271 to herbicide diuron. The 5-day growth inhibition test showed the M.
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