| 1. |
- Batista-Santos, Paula, et al.
(författare)
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Is salt stress tolerance in Casuarina glauca Sieb. ex Spreng. associated with its nitrogen-fixing root-nodule symbiosis? An analysis at the photosynthetic level
- 2015
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 96, s. 97-109
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Tidskriftsartikel (refereegranskat)abstract
- Casuarina glauca is an actinorhizal tree which establishes root-nodule symbiosis with N-2-fixing Frankia bacteria. This plant is commonly found in saline zones and is widely used to remediate marginal soils and prevent desertification. The nature of its ability to survive in extreme environments and the extent of Frankia contribution to stress tolerance remain unknown. Thus, we evaluated the ability of C. glauca to cope with salt stress and the influence of the symbiosis on this trait. To this end, we analysed the impact of salt on plant growth, mineral contents, water relations, photosynthetic-related parameters and nonstructural sugars in nodulated vs. non-nodulated plants. Although the effects on photosynthesis and stomatal conductance started to become measurable in the presence of 200 mM NaCl, photochemical (e.g., photosynthetic electron flow) and biochemical (e.g., activity of photosynthetic enzymes) parameters were only strongly impaired when NaCl levels reached 600 mM. These results indicate the maintenance of high tissue hydration under salt stress, probably associated with enhanced osmotic potential. Furthermore, the maintenance of photosynthetic assimilation potential (A(max)), together with the increase in the quantum yield of down-regulated energy dissipation of PSII (Y-NPQ), suggested a down-regulation of photosynthesis instead of photo-damaging effects. A comparison of the impact of increasing NaCl levels on the activities of photosynthetic (RubisCO and ribulose-5 phosphate kinase) and respiratory (pyruvate kinase and NADH-dependent malate dehydrogenase) enzymes vs. photosynthetic electron flow and fluorescence parameters, revealed that biochemical impairments are more limiting than photochemical damage. Altogether, these results indicate that, under controlled conditions, C glauca tolerates high NaCl levels and that this capacity is linked to photosynthetic adjustments.
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| 2. |
- Fernandes, Isabel, et al.
(författare)
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Salt Stress Tolerance in Casuarina glauca : Insights from the Branchlets Transcriptome
- 2022
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Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 11:21
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and the accelerated rate of population growth are imposing a progressive degradation of natural ecosystems worldwide. In this context, the use of pioneer trees represents a powerful approach to reverse the situation. Among others, N2-fixing actinorhizal trees constitute important elements of plant communities and have been successfully used in land reclamation at a global scale. In this study, we have analyzed the transcriptome of the photosynthetic organs of Casuarina glauca (branchlets) to unravel the molecular mechanisms underlying salt stress tolerance. For that, C. glauca plants supplied either with chemical nitrogen (KNO3+) or nodulated by Frankia (NOD+) were exposed to a gradient of salt concentrations (200, 400, and 600 mM NaCl) and RNA-Seq was performed. An average of ca. 25 million clean reads was obtained for each group of plants, corresponding to 86,202 unigenes. The patterns of differentially expressed genes (DEGs) clearly separate two groups: (i) control- and 200 mM NaCl-treated plants, and (ii) 400 and 600 mM NaCl-treated plants. Additionally, although the number of total transcripts was relatively high in both plant groups, the percentage of significant DEGs was very low, ranging from 6 (200 mM NaCl/NOD+) to 314 (600 mM NaCl/KNO3+), mostly involving down-regulation. The vast majority of up-regulated genes was related to regulatory processes, reinforcing the hypothesis that some ecotypes of C. glauca have a strong stress-responsive system with an extensive set of constitutive defense mechanisms, complemented by a tight mechanism of transcriptional and post-transcriptional regulation. The results suggest that the robustness of the stress response system in C. glauca is regulated by a limited number of genes that tightly regulate detoxification and protein/enzyme stability, highlighting the complexity of the molecular interactions leading to salinity tolerance in this species.
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| 3. |
- Fortunato, Ana, et al.
(författare)
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Isolation and characterization of cgchi3, a nodule-specific gene from Casuarina glauca encoding a class III chitinase
- 2007
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Ingår i: Physiologia Plantarum. - 0031-9317. ; 130:3, s. 418-426
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Tidskriftsartikel (refereegranskat)abstract
- Chitinases (EC 3.2.1.14) catalyse the hydrolysis of chitin, a homopolymer of beta-1,4-linked N-acetyl-D-glucosamine residues. Plant chitinases are involved in a wide variety of processes; in particular, their expression has been found to be enhanced in symbiotic and pathogenic plant-microbe interactions. During this work we have cloned and characterized a gene encoding a class III chitinase from actinorhizal nodules of Casuarina glauca (cgchi3). CGCHI3 was found to be encoded by a single gene that was specifically activated in nodules as compared with uninoculated control roots and leaves. The expression of this gene was further enhanced in nodules after salicylic acid treatment and completely repressed after wounding. In situ hybridisation analysis revealed that cgchi3 is an early nodulin gene, being expressed in the meristem and in the uninfected cortical cells of young nodules. Based on the obtained results we suggest that this gene is involved in nodule development. This is the first report on a class III chitinase coding gene that is specifically activated during actinorhizal symbiosis.
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| 4. |
- Graça, Inês, et al.
(författare)
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Comparative Proteomic Analysis of Nodulated and Non-Nodulated Casuarina glauca Sieb. ex Spreng. Grown under Salinity Conditions Using Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS)
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Casuarina glauca displays high levels of salt tolerance, but very little is known about how this tree adapts to saline conditions. To understand the molecular basis of C. glauca response to salt stress, we have analyzed the proteome from branchlets of plants nodulated by nitrogen-fixing Frankia Thr bacteria (NOD+) and non-nodulated plants supplied with KNO3 (KNO3+), exposed to 0, 200, 400, and 600 mM NaCl. Proteins were identified by Short Gel, Long Gradient Liquid Chromatography coupled to Tandem Mass Spectrometry and quantified by Sequential Window Acquisition of All Theoretical Mass Spectra -Mass Spectrometry. 600 proteins were identified and 357 quantified. Differentially Expressed Proteins (DEPs) were multifunctional and mainly involved in Carbohydrate Metabolism, Cellular Processes, and Environmental Information Processing. The number of DEPs increased gradually with stress severity: (i) from 7 (200 mM NaCl) to 40 (600 mM NaCl) in KNO3+; and (ii) from 6 (200 mM NaCl) to 23 (600 mM NaCl) in NOD+. Protein-protein interaction analysis identified different interacting proteins involved in general metabolic pathways as well as in the biosynthesis of secondary metabolites with different response networks related to salt stress. Salt tolerance in C. glauca is related to a moderate impact on the photosynthetic machinery (one of the first and most important stress targets) as well as to an enhancement of the antioxidant status that maintains cellular homeostasis.
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| 5. |
- Ribeiro, Ana, et al.
(författare)
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Actinorhizal plant defence-related genes in response to symbiotic Frankia
- 2011
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Ingår i: Functional Plant Biology. - 1445-4408 .- 1445-4416. ; 38:8-9, s. 639-644
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Forskningsöversikt (refereegranskat)abstract
- Actinorhizal plants have become increasingly important as climate changes threaten to remake the global landscape over the next decades. These plants are able to grow in nutrient-poor and disturbed soils, and are important elements in plant communities worldwide. Besides that, most actinorhizal plants are capable of high rates of nitrogen fixation due to their capacity to establish root nodule symbiosis with N(2)-fixing Frankia strains. Nodulation is a developmental process that requires a sequence of highly coordinated events. One of these mechanisms is the induction of defence-related events, whose precise role in a symbiotic interaction remains to be elucidated. This review summarises what is known about the induction of actinorhizal defence-related genes in response to symbiotic Frankia and their putative function during symbiosis.
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| 6. |
- Ribeiro-Barros, Ana I., et al.
(författare)
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An integrated approach to understand the mechanisms underlying salt stress tolerance in Casuarina glauca and its relation with nitrogen-fixing Frankia Thr
- 2016
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 70:1, s. 111-116
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Tidskriftsartikel (refereegranskat)abstract
- Salinity is one of the most wide spread abiotic stresses affecting agricultural productivity, with an impact on more than 800 million hectares worldwide. A promising solution for the recovery of saline soils encompasses the use of actinorhizal plants, a group of perennial dicotyledonous angiosperms including species highly resilient to extreme environmental conditions. These plants are able to establish root-nodule symbiosis with N-2-fixing actinobacteria of the genus Frankia. In this review, we discuss the main physiological and biochemical mechanisms underlying salt tolerance in the model Casuarina glauca supplemented with chemical nitrogen or obtaining it from symbiotic Frankia. In the first part, an overview of the impact of increasing NaCl concentrations in photosynthesis, antioxidative system and membrane integrity is presented. The second part addresses the effect of salt stress in the symbiosis between C. glauca and Frankia strain Thr. Preliminary results from analyses of the branchlets proteome and nodule metabolome are presented as well.
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| 7. |
- Santos, Patricia, et al.
(författare)
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Characterization of four defense-related genes up-regulatedin root nodules of Casuarina glauca
- 2010
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Ingår i: Symbiosis. - : Springer. - 0334-5114 .- 1878-7665. ; 50, s. 25-35
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Tidskriftsartikel (refereegranskat)abstract
- Actinorhizal plants are capable of high rates ofnitrogen fixation, due to their capacity to establish a rootnodulesymbiosis with N2-fixing actinomycetes of the genus Frankia. Nodulation is an ontogenic process whichrequires a sequence of highly coordinated events. One of these mechanisms is the induction of defense-relatedevents, whose precise role during nodulation is largelyunknown. In order to contribute to the clarification of the involvement of defense-related genes during actinorhizal root-nodule symbiosis, we have analysed the differential expression of several genes with putative defense-relatedfunctions in Casuarina glauca nodules versus non inoculatedroots. Four genes encoding a chitinase (CgChi1), a glutathione S-transferase (CgGst), a hairpin-inducible protein (CgHin1) and a peroxidase (CgPox4) were found to be up-regulated in mature nodules compared to roots. In order to find out to which extend were the encoded proteins involved in nodule protection, development or both, generegulation studies in response to SA and wounding as wellas phylogenetic analysis of the protein sequences wereperformed. These were further characterized through expression studies after SA-treatment and wounding, and by phylogenetic analysis. We suggest that CgChi1 andCgGst are involved in defense or microsymbiont controland CgPox4 is involved in nodule development. For CgHin1 the question “defense, development or both” remains open.
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