Author
Krystyna Klimaszewska
Other affiliations: Chalk River Laboratories
Bio: Krystyna Klimaszewska is an academic researcher from Natural Resources Canada. The author has contributed to research in topics: Somatic embryogenesis & Callus. The author has an hindex of 36, co-authored 70 publications receiving 3039 citations. Previous affiliations of Krystyna Klimaszewska include Chalk River Laboratories.
Papers published on a yearly basis
Papers
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TL;DR: It is expected that rapid development in the fields of research areas discussed in this review will over time eliminate the problem of recalcitrance in many instances where it is currently prevalent.
Abstract: Despite major advances in forest biotechnology, clonal regeneration by somatic embryogenesis or organogenesis is still difficult for many woody species and is often limited to the use of juvenile explants. Adventitious regeneration of plants from gymnosperms older than zygotic embryos, and frequently even from highly immature zygotic embryos, is often difficult or has not yet been achieved. A number of experimental approaches that could eventually lead to overcoming recalcitrance are suggested in this review. When cloning trees of various ages, it is important to determine first which part of the individual contains the most responsive cells and at what time of the year these cells are in the most responsive state. This allows selection of the most useful explants. In hardwood trees and a few gymnosperms, responsive tissues are found in root or stump sprouts and in tissues near the site of meiosis at about the time that meiosis takes place. Another potentially active area is the shoot apex with most or all of its leaf or needle primordia removed. Apomixis is a natural form of clonal regeneration but occurs naturally in only one gymnosperm species. As the genetic mechanism of apomixis has been in part elucidated, the induction of apomixis by experimental means may soon be possible. The cytoplasm plays a major role in the expression or repression of nuclear genes that control embryogenesis. Expression of nuclear genes can be manipulated by nuclear transfer into de-nucleated cells (e.g., the cytoplasm of egg cells). Cytoplasmic control also plays a role in regeneration by androgenesis, asymmetric cell division and cell isolation. A short overview is presented of the genetic mechanisms involved in embryo initiation, maturation and germination and how manipulation of these mechanisms by genetic transformation could help in overcoming recalcitrance. It is expected that rapid development in the fields of research areas discussed in this review will over time eliminate the problem of recalcitrance in many instances where it is currently prevalent.
188 citations
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TL;DR: Results indicate that in Pinus strobus the water status and possibly other medium characteristics that are influenced by increased concentration of gelling agent have stimulatory effects on maturation of somatic embryos.
Abstract: Application of somatic embryogenesis to Pinus strobus clonal propagation and genetic improvement was hampered by the difficulty in achieving synchronous maturation of a large number of somatic embryos that would germinate and produce plants. Media containing abscisic acid (80 μM) and osmotic agents such as sucrose, polyethylene glycol and/or dextran did not sustain development of mature somatic embryos from plated embryonal masses. This indicated that factors other than osmotic agents might be involved in sustaining development of Pinus strobus somatic embryos to maturity. It was subsequently found that media lacking osmotica but containing a high concentration of gellan gum (1%) induced significant improvement in the development of mature somatic embryos in the presence of 80 or 120 μM abscisic acid. This positive effect was independent of the genotype and all four tested lines displayed similar responses. Media containing gellan gum at concentrations from 0.4 to 1.2% formed gels that varied in their strength. Gel strength was proportional to the concentration of gellan gum in the specific medium but varied depending on the medium formulation. Gel strength increased with the duration of storage of the culture medium by 46% (sD 14) after 14 days of storage. Preliminary results showed that embryos matured on high gellan gum media displayed improved germination frequencies. These results indicate that in Pinus strobus the water status and possibly other medium characteristics that are influenced by increased concentration of gelling agent have stimulatory effects on maturation of somatic embryos.
137 citations
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TL;DR: In both species, maturation of a large number of somatic embryos was greatly improved on medium containing high concentration of gellan gum (Gelrite 10 g l−1) and abscisic acid (60 μM) and this represents a significant improvement in plantlet recovery from somatics embryos of both species.
Abstract: To initiate somatic embryogenesis in Pinus sylvestris and Pinus pinaster, immature seeds were collected from June to August and the developmental stage of the zygotic embryos was determined. Four developmental stages were distinguished and the response of the zygotic embryos at each of the four developmental stages was compared intra- and inter-species. For this study, modified Litvay's medium (LM), with or without growth regulators, was chosen. Somatic embryogenesis was initiated and maintained on both media but the two species displayed different propensities. In P. sylvestris, the highest initiation frequency was obtained with intact megagametophytes containing embryos at the four-cell stage to the stage of cleavage polyembryony (up to 22 and 9%, respectively). The culture medium had no significant effect on the initiation and proliferation of embryogenic cultures. In P. pinaster, however, the best response occurred from excised zygotic embryos at the stage prior to elongation of cotyledon primordia (up to 40% explants responded), on medium with growth regulators. Another characteristic distinguishing the two species in culture was that in some embryogenic cell lines of P. sylvestris, somatic embryos matured spontaneously when initiated and maintained on medium without growth regulators. Some of these embryos developed into plantlets on the same medium at the frequency of 40%. Therefore, in P. sylvestris all the stages of somatic embryogenesis were achieved on the medium without growth regulators. However, in both species, maturation of a large number of somatic embryos was greatly improved on medium containing high concentration of gellan gum (Gelrite 10 g l−1) and abscisic acid (60 μM). Cotyledonary somatic embryos subsequently germinated (72 and 80% for P. sylvestris and P. pinaster, respectively) and developed into plantlets (48 and 29%, for P. sylvestris and P. pinaster, respectively). This represents a significant improvement in plantlet recovery from somatic embryos of both species.
135 citations
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TL;DR: Somatic embryogenesis (SE) initiation in Pinus strobus was optimized by the manipulation of plant growth regulator (PGR) concentrations in the culture medium, indicating that optimized initiation protocol also enhanced somatic embryo production.
Abstract: Somatic embryogenesis (SE) initiation in Pinus strobus was optimized by the manipulation of plant growth regulator (PGR) concentrations in the culture medium. Modified Litvay medium (MLV) of Litvay et al. (1985) supplemented with lower than routinely used PGR concentration increased initiation of established embryogenic cultures from approximately 20 to 53%. The original developmental stage of zygotic embryos had a pronounced effect on the SE response. The optimum stage was the pre- to shortly post-cleavage stage. A substantial genetic influence on initiation of SE was indicated by a significant variance component due to families. Genotype X collection date and genotype X media interactions had large effects on initiation of SE. The PGR levels in the culture medium prior to maturation had a significant effect on subsequent production of mature somatic embryos. Embryogenic tissue initiated and proliferated on medium with a low level of PGR consistently produced a high number of somatic embryos, indicating that optimized initiation protocol also enhanced somatic embryo production. Somatic embryos of 93 embryogenic lines (representing five families) that were initiated on media with different PGR concentrations were converted to plants at an overall frequency of 76%, and grown in the greenhouse. With these improved protocols, application of P. strobus SE in commercial clonal forestry is feasible as an alternative to traditional breeding and reforestation.
116 citations
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TL;DR: Improvements and simplifications of SE protocols in Pinus pinaster (Ait), a species of economic importance in the regions of Western Europe, are described including high initiation frequencies in eight control pollinated seed families, relatively high somatic embryo maturation yield when cells were coated with particles of activated charcoal and a rapid production of plants directly in a shade house.
Abstract: In this study, several improvements and simplifications of SE protocols in Pinus pinaster (Ait.), a species of economic importance in the regions of Western Europe, are described. These improvements pertained to all stages of SE including high initiation frequencies in eight control pollinated seed families, relatively high somatic embryo maturation yield when cells were coated with particles of activated charcoal and a rapid production of plants directly in a shade house. The SE initiation frequency from isolated zygotic embryos was high (up to 100%) and plants were produced from 11 embryogenic lines representing all crosses. Based on these results, the estimated number of somatic embryos required to produce 1,000 plants varied from slightly more than the required number of plants to more than double this number depending on the line. Such an estimate is critical in developing plant production strategy when a number of embryogenic lines are considered for production of clonal plants.
111 citations
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TL;DR: Knowledge of fundamental biological principles embracing both the host and the pathogen have been and will continue to be key to extending the utility of Agrobacterium for genetic engineering purposes.
Abstract: Agrobacterium tumefaciens and related Agrobacterium species have been known as plant pathogens since the beginning of the 20th century. However, only in the past two decades has the ability of Agrobacterium to transfer DNA to plant cells been harnessed for the purposes of plant genetic engineering. Since the initial reports in the early 1980s using Agrobacterium to generate transgenic plants, scientists have attempted to improve this “natural genetic engineer” for biotechnology purposes. Some of these modifications have resulted in extending the host range of the bacterium to economically important crop species. However, in most instances, major improvements involved alterations in plant tissue culture transformation and regeneration conditions rather than manipulation of bacterial or host genes. Agrobacterium-mediated plant transformation is a highly complex and evolved process involving genetic determinants of both the bacterium and the host plant cell. In this article, I review some of the basic biology concerned with Agrobacterium-mediated genetic transformation. Knowledge of fundamental biological principles embracing both the host and the pathogen have been and will continue to be key to extending the utility of Agrobacterium for genetic engineering purposes.
1,269 citations
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01 Jan 1995
TL;DR: This work focuses on Somatic Embryogenesis in African Cycads (Encephalartos) and its application to Clonal Forestry, as well asCryopreservation of Embryogenic Cultures of Conifers and Its Application toclonal Forestry.
Abstract: Section A 1 Somatic Embryogenesis in White Spruce: Studies of Embryo Development and Cell Biology L Kong, et al 2 Proliferative Somatic Embryogenesis in Woody Species K Raemakers, et al 3 Somatic Embryo Germination and Desiccation Tolerance in Conifers EI Hay, PJ Charest 4 Performance of Conifer Stock Produced Through Somatic Embryogenesis SC Grossnickle 5 Apoptosis During Early Somatic Embryogenesis in Picea spp L Havel, DJ Durzan 6 Water Relation Parameters in Conifer Embryos: Methods and Results N Dumont-Beboux, et al 7 Image Analysis for Sorting Somatic Embryos Y Ibaraki 8 Somatic Embryogenesis in Woody Legumes RN Trigiano, et al 9 Cold Storage and Cryopreservation of Camellia Embryogenic Cultures AM Vieitez, A Ballester 10 Cryopreservation of Embryogenic Cultures of Conifers and Its Application to Clonal Forestry DR Cyr 11 Commercialization of Plant Somatic Embryogenesis BCS Sutton, DR Polonenko Section B 12 Somatic Embryogenesis in Myrtaceous Plants JM Canhoto, et al 13 Somatic Embryogenesis Induction in Bay Laurel (Laurus nobilis L) JM Canhoto, et al 14 Somatic Embryogenesis in Simarouba glauca Linn GR Rout, P Das 15 Somatic Embryogenesis in Magnolia spp SA Merkle 16 Somatic Embryogenesis and Evaluation of Variability in Somatic Seedlings of Quercus serata by RAPD Markers K Ishii, et al 17 Somatic Embryogenesis from Immature Fruit of Juglans cinerea PM Pijut Section C 18 Somatic Embrygonesis in Pinus patula Scheide et Deppe NB Jones, J van Staden 19 Somatic Embryogenesis in African Cycads (Encephalartos) AK Jager, J van Staden 20 Somatic Embryogenesis in Picea wilsonii Y Yang, Z Guo 21 Somatic Embryogenesis in Jack Pine (Pinus banksiana Lamb) YS Park, et al 22 Somatic Embryogenesis in Hybrid Firs J Jasik, et al 23 Somatic Embryogenesis in Taxus SR Wann, et al
491 citations
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TL;DR: The effect of AC on growth regulator uptake is still unclear but some workers believe that AC may gradually release certain adsorbed products, such as nutrients and growth regulators which become available to plants.
403 citations
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18 Sep 2003TL;DR: In this paper, a transgenic plant overexpressing a recombinant polynucleotide, wherein the poynucleotide encodes recombinant encodes a polypeptide having at least 95% identity in amino acid sequence over the entire length of SEQ ID nO: 328, was shown to provide improved compared to a non-transgenic plant that does not over-express the poly peptide production.
Abstract: transgenic plant overexpressing a recombinant polynucleotide, wherein said transgenic plant has improved compared production with a non-transgenic plant or wild type plant, wherein the polynucleotide encodes recombinant encodes a polypeptide having at least 95% identity in amino acid sequence over the entire length of SEQ ID nO: 328, said polypeptide providing improved compared to a non-transgenic plant that does not overexpress the polypeptide production.
369 citations