| 1. |
- Aliasgharzad, Nasser, et al.
(författare)
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Lack of arbuscular mycorrhizal colonisation in tea (Camellia sinensis L.) plants cultivated in Northern Iran
- 2011
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 55:2, s. 91-95
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Tidskriftsartikel (refereegranskat)abstract
- Soil and roots associated with different tea clones and nearby weeds (Veronica sp., Setaria sp., Salvia sp., Senecio sp. and Tripogon sp.) were sampled for arbuscular mycorrhizal fungi (AMF) in the tea gardens of Northern Iran. Spores were searched for in the soil and AMF colonisation determined microscopically and fatty acid signatures in roots was determined. Root samples from mycorrhizal and non-mycorrhizal clover were used as positive and negative controls. AMF spores were abundant in the tea garden soils; the genera Glomus and Acaulospora dominated. Microscopic observations of stained tea roots showed no sign of AMF. To confirm this, the roots were analysed for fatty acid signature compounds. The average level of PLFA 16:1 omega 5 as signature molecule for AMF in tea roots was 2 nmol g(-1) dry root, while the NLFA 16: 1 omega 5 was not detectable. In mycorrhizal and non-mycorrhizal clover roots, the PLFA 16:1 omega 5 was 141 and 5.74 nmol g(-1) dry root, respectively. In roots of weeds in tea plantations, the amount of PLFA 16:1 omega 5 was in the range 4.9 to 31.1 nmol g(-1) dry root. Thus, there was no evidence for AMF association in tea roots and weeds are thought to be the source of the spores in the soils. Finally, no mycorrhizal colonisation was found when tea plant seedlings were inoculated with AMF in pot cultures.
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| 2. |
- Ampomah, Osei Y., et al.
(författare)
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Nodulation and ecological significance of indigenous legumes in Scotland and Sweden
- 2012
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Ingår i: Symbiosis. - : Springer Nature. - 0334-5114 .- 1878-7665. ; 57:3, s. 133-148
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Tidskriftsartikel (refereegranskat)abstract
- The ability of wild indigenous legumes to form root nodules capable of biological nitrogen (N 2) fixation has rarely been demonstrated for species in natural ecosystems in large parts of Europe. In order to understand and manage these ecosystems, it is important to demonstrate nodulation across a diverse range of environments, sites and climates. This study surveyed nodulation at a number of sites in Scotland and Sweden. Presence of nodules was noted and nodule structure and indicators of nitrogen fixation capacity were assessed using light and transmission electron microscopy. Soils from several sites were also sampled for carbon and nitrogen analysis. The collections comprised 24 species in Scotland, and 30 taxa in Sweden; 17 of these in common for both countries. Highest species numbers occurred in meadows, farmland margins, hedgerows, roadsides and wasteland. Coastal sites and sites in the mountainous region above the Arctic Circle hosted several rare species. All sampled species had features of N 2-fixing nodules such as pink colour (leghaemoglobin) when dissected and bacteroids. Nodule structure for a number of species is here reported for the first time and presence of the N 2-fixing enzyme nitrogenase is demonstrated in three previously not studied Swedish legume species. North European legumes may make significant contributions to the N-budgets of their ecosystems. Such species (and their symbionts) represent unique germplasm that may be adopted to empower advances in agriculture and conservation aimed at mitigation and adaptation to the effects of climate change.
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| 3. |
- Bargaz, Adnane
(författare)
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Genotypic variation of nodules' enzymatic activities in symbiotic nitrogen fixation among common bean (Phaseolus vulgaris L.) genotypes grown under salinity constraint
- 2013
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 60, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- The effect of salt stress, under glasshouse conditions, was studied on plant biomass, nodulation, and activities of acid phosphatases (APase, EC 3.1.3.2) and trehalose 6-phosphate phosphatase (TPP, EC 3.1.3.12) in the symbiosis common bean (Phaseolus vulgaris L.)-rhizobia nodules. Four common bean recombinant inbred lines (147, 115, 104 and 83) were separately inoculated, with CIAT 899 or RhM11 strains and grown in hydroaeroponic culture. Two NaCl levels (0 and 25 mM NaCl plant(-1) week(-1) corresponding, respectively, to the control and the salt treatment) were applied and the culture was assessed during 42 days after their transplantation. The results showed that the nodulation of these lines was not affected by salinity except for the line 83 inoculated with CIAT 899, whose nodule dry weight decreased by 48.24 % compared with the corresponding controls. For the other symbiotic combinations, shoot and root biomasses were not significantly affected by salt constraint. Salinity stress generally reduced acid phosphatise and trehalose phosphate phosphatase activities in nodules that were less affected in plants inoculated with RhM11. Based on our data, it appears that nodule phosphatase activity may be involved in salinity tolerance in common beans and the levels of salt tolerance depend principally on specific combination of the rhizobial strain and the host cultivar.
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| 4. |
- Carro, Lorena, et al.
(författare)
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Organic acids metabolism in Frankia alni
- 2016
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 70:1, s. 37-48
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Tidskriftsartikel (refereegranskat)abstract
- Trophic exchanges constitute the bases of the symbiosis between the nitrogen-fixing actinomycete Frankia and its host plant Alnus, but the identity of the compounds exchanged is still poorly known. In the current work, previously published transcriptomic studies of Alnus nodules and of symbiotic Frankia were reexamined for TCA cycle related genes. The bacterial TCA enzyme genes were all upregulated, especially the succinyl-CoA synthase and the citrate synthase while on the plant side, none was significantly modified in nodules relative to non-inoculated roots. A preliminary metabolomics approach permitted to see that citrate, 2-oxoglutarate, succinate, malate and fumarate were all more abundant (FC (Fold change) = 5-70) in mature nitrogen-fixing nodules than in roots. In the evaluation of the uptake and metabolism of these organic acids, a significant change was observed in the morphology of nitrogen fixing vesicles in vitro: the dicarboxylates malate, succinate and fumarate induced the formation of larger vesicles than was the case with propionate. Moreover, the production of spores was also modified depending on the organic acid present. The assays showed that most C4 dicarboxylates were taken up while C6 tricarboxylates were not and citrate even partially blocked catabolism of reserve carbon. Tests were performed to determine if the change in membrane permeability induced by Ag5, a peptide previously shown to modify the membranes of Frankia, increased the uptake of specific organic acids. No effect was observed with citrate while an increase in nitrogen fixation was seen with propionate.
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| 5. |
- Chu, Dinh-Toi, et al.
(författare)
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An update on obesity : Mental consequences and psychological interventions
- 2019
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Ingår i: Diabetes & Metabolic syndrome. - : Elsevier. - 1871-4021 .- 1878-0334. ; 13:1, s. 155-160
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Forskningsöversikt (refereegranskat)abstract
- Besides physical consequences, obesity has negative psychological effects, thereby lowering human life quality. Major psychological consequences of this disorder includes depression, impaired body image, low self-esteem, eating disorders, stress and poor quality of life, which are correlated with age and gender. Physical interventions, mainly diet control and energy balance, have been widely applied to treat obesity; and some psychological interventions including behavioral therapy, cognitive behavioral therapy and hypnotherapy have showed some effects on obesity treatment. Other psychological therapies, such as relaxation and psychodynamic therapies, are paid less attention. This review aims to update scientific evidence regarding the mental consequences and psychological interventions for obesity. (c) 2018 Diabetes India. Published by Elsevier Ltd. All rights reserved.
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| 6. |
- Gentili, Francesco
(författare)
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Phosphorus, nitrogen and their interactions affect N-2 fixation, N isotope fractionation and N partitioning in Hippophae rhamnoides
- 2006
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Ingår i: Symbiosis. - 0334-5114 .- 1878-7665. ; 41:1, s. 39-45
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Tidskriftsartikel (refereegranskat)abstract
- The interactive effects of varying phosphorus and nitrogen supplies on N-2 fixation, N isotope fractionation during N uptake, and N partitioning among plant parts were studied in the actinorhizal plant Hippophae rhamnoides L. (sea buckthorn). Plants were grown for six weeks after inoculation with the N-2-fixing actinomycete Frankia and differences in N accumulation were used to quantify N-2 fixation. N-15 natural abundance was analysed to study N isotope fractionation in specific plant parts in plants receiving different levels of N and P. Furthermore, the root system was split to study N isotope fractionation in roots supplied with different levels of N and P. Phosphorus stimulated N-2 fixation by direct effects on nodule dry matter and nodule function, rather than indirectly via plant growth. Phosphorus also stimulated N uptake from solution and influenced N isotope fractionation during N uptake. The inclusion of N-15 natural abundance analyses made it possible to detect P effects on N uptake, fractionation and N-2 fixation even though the plants used both N-2 fixation and combined N as N sources.
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| 7. |
- Gentili, Francesco, et al.
(författare)
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The delta N-15 value of N-2 fixing actinorhizal plants and legumes grown with N-2 as the only nitrogen source
- 2019
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 79, s. 213-219
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the effects of different plant parts and the age of plants at harvest as well as N-2 fixing bacterial strains on the N concentration in symbiotic plant parts, especially on the delta N-15 signature of the actinorhizal plants and legumes. The N-15 natural abundance method was used. Two actinorhizal plants were studied: Alnus incana (L.) infected with the Frankia strains ArI3 or "lsF" (local source of Frankia) and Hippophae rhamnoides (L.) infected with the Frankia strains T1 or E15b. Two legume species were studied: Hedysarum coronarium (L.), infected with a soil suspension, and Robinia pseudoacacia (L.), infected with a crushed nodule suspension. It was particularly interesting that in A. incana, the two Frankia strains affected not only N concentration and delta N-15 signature of leaves and roots, but also had an impact on plant growth at first harvest. In Hippophae rhamnoides plants inoculated with the Frankia strains T1 and E15b, N concentrations and delta N-15 values did not differ at any harvest time. However, plants nodulated by the Frankia strain T1 showed a higher nitrogen fixation rate and higher plant dry matter at all harvesting times. Based on our results for the quantification of N-2 fixation with the "B" value, that is the delta N-15 value of the N-2 fixing plants relying only on N-2 fixation, plant parts, ages and strains should be carefully considered.
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| 8. |
- Huss-Danell, Kerstin
(författare)
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Life in soil by the actinorhizal root nodule endophyte Frankia. A review
- 2010
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 51, s. 201-226
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Forskningsöversikt (refereegranskat)abstract
- Frankia is a genus of soil actinomycetes famous for its ability to form N-2-fixing root nodule symbioses with actinorhizal plants. Although Frankia strains display a high diversity in terms of ecological niches in soil, current knowledge about Frankia is dominated by its life as an endophyte in root nodules. Increased use of molecular methods has refined and expanded insights into endophyte-host specificities and Frankia phylogeny. This review has focus on Frankia as a soil organism, including its part of microbial consortia, and how to study Frankia in soil. We highlight the use of nodulation tests and molecular methods to reveal population size and genetic diversity of Frankia in soil and discuss how autoregulation of nodulation and interactions with other soil microorganisms may influence the results. A comprehensive record of published interactions between Frankia and other soil microbes is summarized.
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| 9. |
- Huss-Danell, Kerstin
(författare)
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Nitrogen fixation by riparian plants belonging to Coriariaceae, Rhamnaceae, and Gunneraceae in Northwest Patagonia
- 2019
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Ingår i: Symbiosis. - : Springer Science and Business Media LLC. - 0334-5114 .- 1878-7665. ; 77, s. 237-247
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen fixation by symbiotic bacteria associated with different plant species is a key process of natural ecosystems. To better understand the role of native N-2-fixing species in the N economy of riparian ecosystems in northwest Patagonia (Argentina), we evaluated: 1) foliar N-15 and N concentrations of actinorhizal Coriaria ruscifolia, Discaria chacaye, and Colletia hystrix, several non-actinorhizal plants (including Gunnera chilensis), and associated soils in riparian forest sites; 2) the proportion of N derived from the atmosphere (Ndfa) of the actinorhizal plant species from riparian forest and of D. chacaye and Ochetophila trinervis from steppe sites; and 3) trends of foliar and soil N-15 and N concentration with mean annual precipitation (MAP). Although soil N concentrations and N-15 did not vary among plant species within any of the sites, foliar N concentration and N-15 differed among species. In general, N-2-fixing species had higher foliar N concentrations and N-15 values closer to 0, the atmospheric value. Both variables separated the groups of N-2-fixing and non-N-2-fixing plant species. Foliar and soil N-15 correlated positively for non-N-2-fixing species but not for N-2-fixing species. Across all sites, the Ndfa of C. ruscifolia and C. hystrix was similar to 100%, similar to 75% for D. chacaye, and similar to 50% for G. chilensis. For all species, foliar N concentration and soil N-15 was negatively correlated with MAP, but only non-N-2-fixing species showed a significant correlation of foliar N-15 with MAP. These data suggest that plant available N decreases as MAP increases but with no effect on N-2-fixing species.
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| 10. |
- Jandér, K. Charlotte
(författare)
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Fitness costs for fig wasps that fail to pollinate their host Ficus perforata
- 2021
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Ingår i: Symbiosis. - : Springer. - 0334-5114 .- 1878-7665. ; 84:2, s. 171-178
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Tidskriftsartikel (refereegranskat)abstract
- Mutualisms are of fundamental ecological importance, but risk breaking down if one partner stops paying the costs yet still takes the benefits of the interaction. To prevent such cheating, many mutualisms have mechanisms that lower the fitness of uncooperative symbionts, often termed host sanctions. In mutualisms where the interacting partners are species-specific, we would expect to see coevolution of the levels of host sanctions and partner cooperation across species-pairs. In the mutualism between fig trees and their species-specific pollinating fig wasps, host sanctions vary greatly in strength, and wasp cooperation levels vary accordingly. Here I show experimentally that in Panamanian Ficus perforata (section Urostigma, Americana) there are fitness costs for wasps that do not pollinate. These fitness costs are caused by a combination of abortions of unpollinated figs and reduced proportion of wasp larvae that successfully develop to adults. The relative fitness of wasps that do not pollinate compared to wasps that pollinate is 0.59, leading to the intermediate sanction strength 0.41. Next, by screening pollinators of F. perforata I found that 1.9% of wasp individuals in natural populations failed to carry pollen. Across five actively pollinated Neotropical fig species and their pollinators, fig species with stronger host sanctions had fewer uncooperative wasps, as would be expected if sanctions promote cooperation.
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