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| 2. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Abrahamsson, Malin, et al.
(författare)
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Patterning during somatic embryogenesis in Scots pine in relation to polar auxin transport and programmed cell death
- 2012
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Ingår i: Plant Cell, Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 109, s. 391-400
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Tidskriftsartikel (refereegranskat)abstract
- Somatic embryogenesis is a useful tool to propagate conifers vegetatively. However, a major limitation in many pine species is the low quality of cotyledonary somatic embryos. The aim of this study has been to elucidate the developmental pathway of somatic embryos in Scots pine (Pinus sylvestris), to identify deviations from the normal pathway and to identify processes that might disturb normal development. Initially we compared the developmental pathway of somatic embryogenesis in representative cell lines yielding cotyledonary embryos with normal and abnormal morphology. Early embryos carrying suspensor cells in excess of the normal number (supernumerary) were more frequent in cell lines giving rise to abnormal cotyledonary embryos. In this study we show that the frequency of early somatic embryos with supernumerary suspensor cells increased after treatment with the auxin transport inhibitor 1-N-naphtylphthalamic acid (NPA). Furthermore, the yield of developing embryos increased significantly after treatment with the antiauxin 2-(4-chlorophenoxy)-2-methylpropionic acid (PCIB), but the morphology of the embryos was not affected. The number of cells undergoing PCD was analyzed using a TUNEL-assay. The frequency of TUNEL-positive cells was high both in proliferating cultures and during differentiation of early somatic embryos. However, the pattern of TUNEL-positive cells was similar in normal somatic embryos and in embryos with supernumerary suspensor cells. Together our results suggest that the presence of supernumerary suspensor cells in early somatic embryos of Scots pine is caused by disturbed polar auxin transport and results in aberrant embryo development.
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| 4. |
- Abrahamsson, Malin, et al.
(författare)
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Somatic Embryogenesis in Scots Pine (Pinus sylvestris L.)
- 2018
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Ingår i: STEP WISE PROTOCOLS FOR SOMATIC EMBRYOGENESIS OF IMPORTANT WOODY PLANTS, VOL I, 2ND EDITION. - Cham : Springer International Publishing. - 9783319894829 ; 84:84, s. 123-133
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Bokkapitel (refereegranskat)abstract
- Scots pine (Pinus sylvestris L.) can be propagated via somatic embryogenesis. However, the protocols available today are not sufficient for large-scale propagation. The method needs to be optimized in order to increase the initiation frequency of embryogenic cell lines giving rise to high quality cotyledonary embryos, and to improve somatic embryo germination. Protocols presented in this chapter have been used to carry out fundamental research, where the resulting knowledge will be valuable for improving culture conditions for large scale propagation of Pinus species via somatic embryogenesis.
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| 5. |
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| 6. |
- Dahrendorf, Julia, et al.
(författare)
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Analysis of Nitrogen Utilization Capability during the Proliferation and Maturation Phases of Norway Spruce (Picea abies (L.) H.Karst.) Somatic Embryogenesis
- 2018
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Somatic embryogenesis (SE) is a laboratory-based method that allows for cost-effective production of large numbers of clonal copies of plants, of particular interest for conifers where other clonal propagation methods are mostly unavailable. In this study, the effect of l-glutamine as an organic nitrogen source was evaluated for three contrasted media (containing NH4 + NO3 without glutamine, or glutamine + NO3, or glutamine without inorganic nitrogen) during proliferation and maturation of Norway spruce somatic embryos through analyses of activities of the key enzymes of nitrogen metabolism: nitrate reductase (NR), glutamine synthetase (GS) and arginase. A major change in nitrogen metabolism was indicated by the increased activity of GS from zero in the proliferation stage through maturation to high activity in somatic embryo-derived plantlets; furthermore, NR activity increased from zero at the proliferation stage to high activity in maturing embryos and somatic-embryo derived plantlets. In contrast, arginase activity was high at all stages. In accordance with the GS and NR data, proliferation was fastest on the glutamine media, the largest number of mature embryos developed on the glutamine medium without inorganic nitrogen, and the ammonium content of proliferating cultures was much higher than that of mature somatic embryos. The best developed embryos, judged by germination, were from the glutamine + NO3 medium. These insights into nitrogen utilization will help to improve culture medium composition.
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| 7. |
- Dobrowolska, Izabela, et al.
(författare)
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Histological analysis reveals the formation of shoots rather than embryos in regenerating cultures of Eucalyptus globulus
- 2017
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Ingår i: Plant Cell, Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 128, s. 319-326
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Tidskriftsartikel (refereegranskat)abstract
- Eucalyptus globulus is an important species in international forestry in regions with Mediterranean climates and comprises 65 % of the plantation hardwood in Australia. Propagation by somatic embryogenesis would offer many advantages and its development has received much attention. Structures regenerating on explants from hypocotyls of mature zygotic embryos of E. globulus cultured on medium with NAA, reported previously to be effective for embryogenic regeneration, were analyzed morphologically and histologically to clarify their pathway of development. Analysis of series of sections revealed organogenic, rather than embryogenic, pathways of regeneration in this system. We show that protocols for propagation of E. globulus must be carefully evaluated by microscopic examination of adequate numbers of serial sections.
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| 8. |
- Egertsdotter, Ulrika, et al.
(författare)
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Automation and Scale Up of Somatic Embryogenesis for Commercial Plant Production, With Emphasis on Conifers
- 2019
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 10
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Forskningsöversikt (refereegranskat)abstract
- For large scale production of clonal plants, somatic embryogenesis (SE) has many advantages over other clonal propagation methods such as the rooting of cuttings. In particular, the SE process is more suited to scale up and automation, thereby reducing labor costs and increasing the reliability of the production process. Furthermore, the plants resulting from SE closely resemble those from seeds, as somatic embryos, like zygotic (seed) embryos, develop with good connection between root and shoot, and without the plagiotropism often associated with propagation by cuttings. For practical purposes in breeding programs and for deployment of elite clones, it is valuable that a virtually unlimited number of SE plants can be generated from one original seed embryo; and SE cultures (clones) can be cryostored for at least 20 years, allowing long-term testing of clones. To date, there has however been limited use of SE for large-scale plant production mainly because without automation it is labor-intensive. Development of automation is particularly attractive in countries with high labor costs, where conifer forestry is often of great economic importance. Various approaches for automating SE processes are under investigation and the progress is reviewed here, with emphasis on conifers. These approaches include simplification of culture routines with preference for liquid rather than solid cultures, use of robotics and automation for the harvest of selected individual mature embryos, followed by automated handling of germination and subsequent planting. Different approaches to handle the processes of somatic embryogenesis in conifers are outlined below, followed by an update on efforts to automate the different steps, which are nearing an operational stage.
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| 9. |
- Eriksson, Gösta, et al.
(författare)
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Genetics Applied to Forestry : an introduction
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This book is a follow-up of An Introduction to Forest Genetics. It is somewhat expanded compared to the book printed in 2007. We were encouraged to "publish" the revised version of the textbook on the internet. Undergraduate students are the target group as well as graduate students with limited experience of forest genetics. Without the advice and help from Kjell Lännerholm, Björn Nicander, Johan Samuelsson and Hartmut Weichelt the editing would have been more troublesome. We express our sincere thanks to them. A generous grant from Föreningen Skogsträdsförädling, The Tree Breeding Association in Sweden, made this printing possible. A web version of this book may be found under http://vaxt2.vbsg.slu.se/forgen/Forestry_Genetics.pdf
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| 10. |
- Grander, Martin
(författare)
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For the Benefit of Everyone? : Explaining the Significance of Swedish Public Housing for Urban Housing Inequality
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Housing has a special place in the Swedish welfare state. Ever since Gustav Möller, Minister for Social Affairs, in 1945 was handed the result of Bostadssociala utredningen, a state investigation on housing from a social perspective, housing has been a bearing pillar in the Swedish ‘Folkhem’. Since the post-war period, Swedish housing policy has been universal in the sense that housing consumers have not been categorized by income or living conditions. Instead, the policy has had the aim of ‘good housing for all’. The main instrument for achieving this goal—the figurehead of the universal housing policy—has been allmännyttan, the national model of public housing, constituted by municipal housing companies with the task of offering rental housing of high quality, for the benefit of everyone. This PhD thesis analyzes allmännyttan based on the observation that the contemporary housing situation is largely characterized by inequality. The housing consumer is to a lesser extent independent from inherited conditions: Access to housing and the characteristics of housing are increasingly dependent on economic resources. The dissertation highlights the role of public housing in this development. The municipal housing companies and the context they exist in have changed over the past decades through gradual political reforms and alignment with European competition law. Such a development might influence the ability of allmännyttan to contribute to keeping housing inequality at bay. The purpose of the thesis is thus to study the potential and actual significance of allmännyttan for housing inequality in Swedish cities. The thesis is grounded in critical realist ontology and analyzes how and why (or why not) allmännyttan’s latent mechanisms to counteract inequality are actualized. Through studies of municipal housing companies throughout Sweden, including eleven in-depth case studies, the thesis seeks to answer whether the contemporary allmännytta counteracts housing inequality, or if it rather contributes to a more unequal housing provision. The dissertation consists of three peer-reviewed papers. Together with the framing chapter of the dissertation, the papers highlight how housing inequality could be understood from a national context and in terms of multidimensionality; how events triggered by allmännyttan counteracts or contributes to housing inequality; and how allmännyttan’s discretion to counteract housing inequality is identified and used by the municipal housing companies. The results indicate that, despite a gradual shift towards businesslike conditions and demands on return on investment, allmännyttan still has a latent and potential ability to counteract housing inequality. The core of universalism consists, so do the expectations of social benefit. However, the contextual conditions have changed: The state-organized housing provision has gone from state-financed to financialized, i.e., dependent on financial motives, institutions, tools and financial capital. Allmännyttan exists in a state of financialized universalism. In spite of this development, the thesis identifies ample discretion for municipal housing companies to actualize underlying mechanisms which contribute to counteracting housing inequality. However, how this discretion is perceived and used varies from city to city. The discretion is interpreted—consciously or unconsciously— in different ways, depending on the local political governance, but also on the local institutional path-dependence, i.e., its past decisions, its culture and traditions. How the discretion is identified has implications on the events that affect housing inequality. The conclusion is that public housing is more than ever locally diversified. An imaginary of financialized economy has been adopted by many municipal housing companies, but this imaginary is challenged and negotiated by other companies. Given this variation, allmännyttan simultaneously—and contradictory—contributes to both reduced and increased housing inequality. The character of the ambiguous allmännytta is thus determined at local scale, a conclusion which stands in contrast with national objectives of a state-organized housing provision based on good housing, for the benefit of everyone.
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