| 1. |
- Menkveld, Albert J., et al.
(författare)
-
Nonstandard Errors
- 2024
-
Ingår i: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
-
Tidskriftsartikel (refereegranskat)abstract
- In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
|
|
| 2. |
|
|
| 3. |
- Niemi, MEK, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 4. |
- Abrahamsson, Malin, et al.
(författare)
-
Patterning during somatic embryogenesis in Scots pine in relation to polar auxin transport and programmed cell death
- 2012
-
Ingår i: Plant Cell, Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 109, s. 391-400
-
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.
|
|
| 5. |
- Abrahamsson, Malin, et al.
(författare)
-
Somatic Embryogenesis in Scots Pine (Pinus sylvestris L.)
- 2018
-
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
-
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.
|
|
| 6. |
|
|
| 7. |
- Dahrendorf, Julia, et al.
(författare)
-
Analysis of Nitrogen Utilization Capability during the Proliferation and Maturation Phases of Norway Spruce (Picea abies (L.) H.Karst.) Somatic Embryogenesis
- 2018
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 9
-
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.
|
|
| 8. |
- Dobrowolska, Izabela, et al.
(författare)
-
Histological analysis reveals the formation of shoots rather than embryos in regenerating cultures of Eucalyptus globulus
- 2017
-
Ingår i: Plant Cell, Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 128, s. 319-326
-
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.
|
|
| 9. |
- Egertsdotter, Ulrika, et al.
(författare)
-
Automation and Scale Up of Somatic Embryogenesis for Commercial Plant Production, With Emphasis on Conifers
- 2019
-
Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 10
-
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.
|
|
| 10. |
- Eriksson, Gösta, et al.
(författare)
-
Genetics Applied to Forestry : an introduction
- 2013
-
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
|
|
| 11. |
- Grander, Martin
(författare)
-
For the Benefit of Everyone? : Explaining the Significance of Swedish Public Housing for Urban Housing Inequality
- 2018
-
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.
|
|
| 12. |
- Grönroos, Roland, et al.
(författare)
-
Transgenic rooting in conifers
- 1997
-
Ingår i: Biology of Root Formation and Development. - : Plenum Press New York and London. ; , s. 175-180
-
Bokkapitel (populärvet., debatt m.m.)
|
|
| 13. |
- Gyllenstrand, Niclas, et al.
(författare)
-
A Norway spruce FLOWERING LOCUS T homolog is implicated in control of growth rhythm in conifers
- 2007
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 144:1, s. 248-257
-
Tidskriftsartikel (refereegranskat)abstract
- Growth in perennial plants possesses an annual cycle of active growth and dormancy that is controlled by environmental factors, mainly photoperiod and temperature. In conifers and other nonangiosperm species, the molecular mechanisms behind these responses are currently unknown. In Norway spruce (Picea abies L. Karst.) seedlings, growth cessation and bud set are induced by short days and plants from southern latitudes require at least 7 to 10 h of darkness, whereas plants from northern latitudes need only 2 to 3 h of darkness. Bud burst, on the other hand, is almost exclusively controlled by temperature. To test the possible role of Norway spruce FLOWERING LOCUS T (FT)-like genes in growth rhythm, we have studied expression patterns of four Norway spruce FT family genes in two populations with a divergent bud set response under various photoperiodic conditions. Our data show a significant and tight correlation between growth rhythm (both bud set and bud burst), and expression pattern of one of the four Norway spruce phosphatidylethanolamine-binding protein gene family members (PaFT4) over a variety of experimental conditions. This study strongly suggests that one Norway spruce homolog to the FT gene, which controls flowering in angiosperms, is also a key integrator of photoperiodic and thermal signals in the control of growth rhythms in gymnosperms. The data also indicate that the divergent adaptive bud set responses of northern and southern Norway spruce populations, both to photoperiod and light quality, are mediated through PaFT4. These results provide a major advance in our understanding of the molecular control of a major adaptive trait in conifers and a tool for further molecular studies of adaptive variation in plants.
|
|
| 14. |
|
|
| 15. |
- Karlgren, Anna, et al.
(författare)
-
FLOWERING LOCUS T/TERMINAL FLOWER1-Like Genes Affect Growth Rhythm and Bud Set in Norway Spruce
- 2013
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 163:2, s. 792-803
-
Tidskriftsartikel (refereegranskat)abstract
- The timing of bud set, as one determinant of the annual growth rhythm, is critical for local adaptation of the conifer Norway spruce (Picea abies). Previous gene expression and population genetic studies have suggested a role for P. abies FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (PaFTL2) in the control of growth cessation and bud set in Norway spruce as well as in local adaptation resulting in clinal variation for timing of bud set. Using transgenic plants with PaFTL2 driven by an inducible promoter, we found that PaFTL2 indeed induces bud set and most probably also growth cessation. PaFTL2 shows high expression around the procambium and vascular tissue and in the crown region in buds of both seedlings and older trees. Furthermore, PaFTL2 expression is induced in vegetative shoots and all bud types in late summer, when growth cessation occurs. This supports the notion that PaFTL2 is involved in growth cessation. A close paralog to PaFTL2, PaFTL1, is strongly expressed in meristems during the summer, possibly to repress meristem activity and the formation of needle primordia during this period. The temporal and spatial expression of PaFTL1 and PaFTL2 largely complement each other, which suggests that they act in concert to control perennial growth in Norway spruce.
|
|
| 16. |
- Kien, Nguyen Duc, et al.
(författare)
-
Cellulose content as a selection trait in breeding for kraft pulp yield in Eucalyptus urophylla
- 2009
-
Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 66
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the effectiveness of using cellulose content, measured by the diglyme-HCl method, as a selection trait in breeding programs for kraft pulp yield in Eucalyptus urophylla.A total of 275 trees from sixty-two families were sampled from a thinned progeny trial of E. urophylla in northern Vietnam to evaluate cellulose content from breast-height increment cores. Among those, twenty unrelated trees were felled to evaluate cellulose content and pulp yield from breast-height disk samples.The regression of pulp yield of disk samples on cellulose content was strong either from disks (R(2) = 0.83) or increment cores (R(2) = 0.69). There was no significant difference in cellulose content between the provenances. The narrow-sense within-provenance heritability of cellulose content was 0.50 and the coefficient of additive genetic variation was 3.9%. Genetic correlations between cellulose content and growth (0.28-0.45) or wood basic density (-0.02) were not significantly different from zero.Breast-height increment core cellulose content measured by diglyme-HCl method is under strong genetic control and can be used to rank trees for pulp yield in E. urophylla plantations. Selection for increased cellulose content would have only minor effects on growth and wood basic density.
|
|
| 17. |
- Lindroth, Anders M., et al.
(författare)
-
Two S-adenosylmethionine synthetase-encoding genes that are differentially expressed during adventitious root development in Pinus Contorta
- 2001
-
Ingår i: Plant Molecular Biology. - 0167-4412 .- 1573-5028. ; 46:3, s. 335-346
-
Tidskriftsartikel (refereegranskat)abstract
- Two S-adenosylmethionine synthetase (SAMS) cDNAs, PcSAMS1 and PcSAMS2, have been identified in Pinus contorta. We found that the two genes are differentially expressed during root development. Thus, PcSAMS1 is preferentially expressed in roots and exhibits a specific expression pattern in the meristem at the onset of adventitious root development, whereas PcSAMS2 is expressed in roots as well as in shoots and is down-regulated during adventitious root formation. The expression of the two SAMS genes is different from the SAMS activity levels during adventitious root formation. We conclude that other SAMS genes that remain to be characterized may contribute to the observed SAMS activity, or that the activities of PcSAMS1 and PcSAMS2 are affected by post-transcriptional regulation. The deduced amino acid sequences of PcSAMS1 and PcSAMS2 are highly divergent, suggesting different functional roles. However, both carry the two perfectly conserved motifs that are common to all plant SAMS. At the protein level, PcSAMS2 shares about 90% identity to other isolated eukaryotic SAMS, while PcSAMS1 shares less than 50% identity with other plant SAMS. In a phylogenetic comparison, PcSAMS1 seems to have diverged significantly from all other SAMS genes. Nevertheless, PcSAMS1 was able to complement a Saccharomyces cerevisiae sam1 sam2 double mutant, indicating that it encodes a functional SAMS enzyme.
|
|
| 18. |
|
|
| 19. |
- Minina, Alyona, et al.
(författare)
-
Autophagy and metacaspase determine the mode of cell death in plants
- 2013
-
Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 203, s. 917-927
-
Tidskriftsartikel (refereegranskat)abstract
- Although animals eliminate apoptotic cells using macrophages, plants use cell corpses throughout development and disassemble cells in a cell-autonomous manner by vacuolar cell death. During vacuolar cell death, lytic vacuoles gradually engulf and digest the cytoplasmic content. On the other hand, acute stress triggers an alternative cell death, necrosis, which is characterized by mitochondrial dysfunction, early rupture of the plasma membrane, and disordered cell disassembly. How both types of cell death are regulated remains obscure. In this paper, we show that vacuolar death in the embryo suspensor of Norway spruce requires autophagy. In turn, activation of autophagy lies downstream of metacaspase mcII-Pa, a key protease essential for suspensor cell death. Genetic suppression of the metacaspase-autophagy pathway induced a switch from vacuolar to necrotic death, resulting in failure of suspensor differentiation and embryonic arrest. Our results establish metacaspase-dependent autophagy as a bona fide mechanism that is responsible for cell disassembly during vacuolar cell death and for inhibition of necrosis.
|
|
| 20. |
- Quang, Tran Ho, et al.
(författare)
-
EVALUATING POPULATION STRUCTURE BY NEUTRAL MARKERS AND QUANTITATIVE GENETIC PARAMETERS IN A THINNED PROGENY TRIAL OF EUCALYPTUS UROPHYLLA
- 2013
-
Ingår i: Journal of Tropical Forest Science. - 0128-1283. ; 25, s. 350-360
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to estimate from microsatellite variation the levels of homozygote excess within nine populations comprising a combined population and progeny trial of Eucalyptus urophylla in northern Vietnam and to compare the population differentiation estimated by molecular markers with that estimated from growth traits. The material was thinned in year 2 (removing 75% of the trees) and year 5 (removing 37% of the remaining trees). Microsatellite variation was measured after the second thinning. Homozygote excess (F-IS) among populations ranged from 0.069 to 0.198. Most of the molecular variation was within populations (97.1% of the total variation), in agreement with the low FST value (0.023) of neutral molecular markers (F-ST) (0.023). Estimates of quantitative trait differentiation (Q(ST)) based on a univariate model among populations for height and diameter at breast height were low over the first eight years of the trial, at most 0.21. This presumably reflected selection for the same traits in a common environment. The differences between Q(ST) after the second thinning and F-ST, a measure of the effects of selection, were also small. Prospects for further breeding progress are bright, whether or not crosses are made among populations.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Sriskandarajah, Sridevy, et al.
(författare)
-
Development of a genetic transformation method for seabuckthorn ( Hippophae rhamnoides L.).
- 2014
-
Ingår i: American Journal of Plant Sciences. - : Scientific Research Publishing, Inc.. - 2158-2742 .- 2158-2750. ; 5, s. 528-534
-
Tidskriftsartikel (refereegranskat)abstract
- Seabuckthorn (Hippophae rhamnoides L.) is a dioecious plant with berries containing highamounts of several bioactive compounds with nutritional and medicinal traits. It is also planted tocontrol soil erosion. A genetic transformation procedure will facilitate studies of the control ofplant development and interactions with symbionts and pathogens, and will provide a tool forplant breeding. Here, we present a particle bombardment method for transforming seabuckthorn.The early stages of induced adventitious shoots from roots were chosen as a novel target tissue forthe transformation procedure. The root system was bombarded with gold particles coated withplasmid pRT99gus containing genes for plant kanamycin resistance and for β-glucuronidase expression,and shoots were regenerated under kanamycin selection. PCR analysis of the regeneratedtransformed lines confirmed the presence of a 603 bp gus (uidA) gene fragment and a 1.5 kbfragment from the 35S promoter in three shoots from independent transformation events.
|
|
| 24. |
- Uddenberg, Daniel, et al.
(författare)
-
Early Cone Setting in Picea abies acrocona Is Associated with Increased Transcriptional Activity of a MADS Box Transcription Factor
- 2013
-
Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 161:2, s. 813-823
-
Tidskriftsartikel (refereegranskat)abstract
- Conifers normally go through a long juvenile period, for Norway spruce (Picea abies) around 20 to 25 years, before developing male and female cones. We have grown plants from inbred crosses of a naturally occurring spruce mutant (acrocona). One-fourth of the segregating acrocona plants initiate cones already in their second growth cycle, suggesting control by a single locus. The early cone-setting properties of the acrocona mutant were utilized to identify candidate genes involved in vegetative-to-reproductive phase change in Norway spruce. Poly(A(+)) RNA samples from apical and basal shoots of cone-setting and non-cone-setting plants were subjected to high-throughput sequencing (RNA-seq). We assembled and investigated 33,383 expressed putative protein-coding acrocona transcripts. Eight transcripts were differentially expressed between selected sample pairs. One of these (Acr42124_1) was significantly up-regulated in apical shoot samples from cone-setting acrocona plants, and the encoded protein belongs to the MADS box gene family of transcription factors. Using quantitative real-time polymerase chain reaction with independently derived plant material, we confirmed that the MADS box gene is up-regulated in both needles and buds of cone-inducing shoots when reproductive identity is determined. Our results constitute important steps for the development of a rapid cycling model system that can be used to study gene function in conifers. In addition, our data suggest the involvement of a MADS box transcription factor in the vegetative-to-reproductive phase change in Norway spruce.
|
|
| 25. |
|
|
| 26. |
- Von Arnold, Sara, et al.
(författare)
-
Embryology in conifers
- 2019
-
Ingår i: Advances in Botanical Research. - : Elsevier. - 0065-2296. ; 89, s. 157-184
-
Forskningsöversikt (refereegranskat)abstract
- Conifers, which grow in all climate zones, are important both ecologically and economically. An understanding of the regulation of the development of coniferous trees from single cells to mature trees is critical for scientific and biotechnological applications. Early embryogenesis is a crucial developmental phase during which the basic features of the plant body are established: the apical-basal axis of polarity, the various tissue layers, and the root and the shoot poles. Conifer somatic embryogenesis is of special interest both as a model system for zygotic embryogenesis and because of its potential for mass propagation of selected genotypes. The cell and molecular biology of higher plant embryogenesis has been most studied in the angiosperm Arabidopsis. Like seeds in Arabidopsis, conifer seeds contain a simple mature embryo. However, the patterning of cell division and cell differentiation leading to the final shape are dramatically different in the two groups of species. This is not surprising since the common ancestor of gymnosperms and angiosperms dates from ca. 300Myr ago. The aim of this review is to give an updated survey of the developmental patterning and its regulation during zygotic and somatic embryogenesis in conifers, particularly the genera Picea and Pinus. Somatic embryogenesis biotechnology is much affected by the occurrence of cleavage polyembryony in Pinus and its absence in Picea.
|
|
| 27. |
- Von Arnold, Sara, et al.
(författare)
-
Regulation of Somatic Embryo Development in Norway Spruce
- 2020
-
Ingår i: Plant Embryogenesis : Methods and Protocols. - New York, NY : Springer US. - 9781071603413 ; 2122:2122, s. 241-255
-
Bokkapitel (refereegranskat)abstract
- Somatic embryogenesis in Norway spruce combined with reverse genetics can be used as a model to study the regulation of embryo development in conifers. The somatic embryo system includes a sequence of developmental stages, which are similar in morphology to their zygotic counterparts. The system can be sufficiently synchronized to enable the collection and study of a large number of somatic embryos at each developmental stage. Here we describe a protocol for establishing transgenic cell lines in which genes of interest are upregulated or downregulated. Furthermore, we present methods for comparing embryo morphology and development in transgenic and control cell lines, including phenotyping the embryos, histological analysis, and tracking embryo development. The expression pattern of different genes is determined by GUS reporter assays.
|
|
| 28. |
- Wadenback, Johan, et al.
(författare)
-
Lignin biosynthesis in transgenic Norway spruce plants harboring an antisense construct for cinnamoyl CoA reductase (CCR)
- 2008
-
Ingår i: Transgenic research. - : Springer Science and Business Media LLC. - 0962-8819 .- 1573-9368. ; 17:3, s. 379-392
-
Tidskriftsartikel (refereegranskat)abstract
- An attractive objective in tree breeding is to reduce the content of lignin or alter its composition, in order to facilitate delignification in pulping. This has been achieved in transgenic angiosperm tree species. In this study we show for the first time that changes in lignin content and composition can be achieved in a conifer by taking a transgenic approach. Lignin content and composition have been altered in five-year-old transgenic plants of Norway spruce (Picea abies [L.] Karst) expressing the Norway spruce gene encoding cinnamoyl CoA reductase (CCR) in antisense orientation. The asCCR plants had a normal phenotype but smaller stem widths compared to the transformed control plants. The transcript abundance of the sense CCR gene was reduced up to 35% relative to the transformed control. The corresponding reduction in lignin content was up to 8%, which is at the lower limit of the 90-99% confidence intervals reported for natural variation. The contribution of H-lignin to the non-condensed fraction of lignin, as judged by thioacidolysis, was reduced up to 34%. The H-lignin content was strongly correlated with the total lignin content. Furthermore, the kappa number of small-scale Kraft pulps from one of the most down-regulated lines was reduced 3.5%. The transcript abundances of the various lignin biosynthetic genes were down-regulated indicating co-regulation of the biosynthetic pathway.
|
|
| 29. |
|
|
| 30. |
- Kanai, M, et al.
(författare)
-
- 2023
-
swepub:Mat__t
|
|
