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Munzi S, Sheppard LJ, Leith ID, Cruz C, Branquinho C, Bini L, Gagliardi A, Cai G, Parrotta L. The cost of surviving nitrogen excess: energy and protein demand in the lichen Cladonia portentosa as revealed by proteomic analysis. PLANTA 2017; 245:819-833. [PMID: 28054148 DOI: 10.1007/s00425-017-2647-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/01/2017] [Indexed: 05/10/2023]
Abstract
Different nitrogen forms affect different metabolic pathways in lichens. In particular, the most relevant changes in protein expression were observed in the fungal partner, with NO 3- mostly affecting the energetic metabolism and NH 4+ affecting transport and regulation of proteins and the energetic metabolism much more than NO 3- did. Excess deposition of reactive nitrogen is a well-known agent of stress for lichens, but which symbiont is most affected and how, remains a mystery. Using proteomics can expand our understanding of stress effects on lichens. We investigated the effects of different doses and forms of reactive nitrogen, with and without supplementary phosphorus and potassium, on the proteome of the lichen Cladonia portentosa growing in a 'real-world' simulation of nitrogen deposition. Protein expression changed with the nitrogen treatments but mostly in the fungal partner, with NO3- mainly affecting the energetic metabolism and NH4+ also affecting the protein synthesis machinery. The photobiont mainly responded overexpressing proteins involved in energy production. This suggests that in response to nitrogen stress, the photobiont mainly supports the defensive mechanisms initiated by the mycobiont with an increased energy production. Such surplus energy is then used by the cell to maintain functionality in the presence of NO3-, while a futile cycle of protein production can be hypothesized to be induced by NH4+ excess. External supply of potassium and phosphorus influenced differently the responses of particular enzymes, likely reflecting the many processes in which potassium exerts a regulatory function.
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Affiliation(s)
- Silvana Munzi
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Bloco C2, 1749-016, Lisbon, Portugal.
| | - Lucy J Sheppard
- Centre for Ecology and Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - Ian D Leith
- Centre for Ecology and Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, EH26 0QB, UK
| | - Cristina Cruz
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Bloco C2, 1749-016, Lisbon, Portugal
| | - Cristina Branquinho
- Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Bloco C2, 1749-016, Lisbon, Portugal
| | - Luca Bini
- Department of Life Sciences, University of Siena, Via Aldo Moro, 2, 53100, Siena, Italy
| | - Assunta Gagliardi
- Department of Life Sciences, University of Siena, Via Aldo Moro, 2, 53100, Siena, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, Via Pier Andrea Mattioli, 4, 53100, Siena, Italy
| | - Luigi Parrotta
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio, 42, 40126, Bologna, Italy
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Freitag S, Feldmann J, Raab A, Crittenden PD, Hogan EJ, Squier AH, Boyd KG, Thain S. Metabolite profile shifts in the heathland lichen Cladonia portentosa in response to N deposition reveal novel biomarkers. PHYSIOLOGIA PLANTARUM 2012; 146:160-172. [PMID: 22324764 DOI: 10.1111/j.1399-3054.2012.01593.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The heathland lichen Cladonia portentosa was collected from sites in mainland Britain differing either in rates of wet N deposition or in annual mean N concentration in rainfall based on a modelled data set. Methanolic extracts of thalli were analyzed by liquid chromatography time-of-flight mass spectrometry to yield metabolic profiles. Differences between sites in metabolite concentration were quantified using multivariate statistical tools and used to identify potential biomarker molecules. The abundances of three structurally related betaine lipids showed an increase with increasing modelled N deposition to a threshold of 22.3 kg ha(-1) year(-1) after which they remained constant. In contrast, the abundance of a phosphatidylcholine (PC) lipid showed concomitant decrease. Correlations of the identified biomarkers with N deposition and precipitation were stronger than those with N concentrations. The results presented in this study clearly show that N enrichment associated with tissue P limitation changes lipid composition, leading to shifts from PCs to betaine lipids, and that these lipids identified have the potential to be used as biomarkers for nitrogen enrichment.
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Affiliation(s)
- Sabine Freitag
- Environmental Research Institute, University of the Highlands and Islands, Castle Street, Thurso, KW14 7JD, Scotland, UK
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