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.

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Agrobacterium-Mediated Plant Transformation: the Biology behind the “Gene-Jockeying” Tool

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

Somatic embryogenesis in woody plants

Terpenoid biomaterials

The role of activated charcoal in plant tissue culture.

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.

Polynucleotides and polypeptides in plants

Pinus pinea L. (stone pine) is one of the major plantation species in Iberian Peninsula, being Portugal the largest edible seed producer in the world. The induction and improvement of in vitro rhizogenesis of microshoots of Pinus pinea was developed in our laboratory using a co-culture system with ECM fungi. In the acclimation phase in mixed substrates, or in rhizotrons, anatomical and morphological studies were done to observe the evolution of the root system in microshoots from the co-culture system vs. control plants. Extensive dichotomous and coralloid branching of lateral roots occurred spontaneously in inoculated and control plants as well. Moreover, similar branching occurred in liquid culture of excised seedling roots without the presence of ECM fungi. The striking similarity of these organs with pine ectomycorrhizas prompted their anatomical analysis; however the presence of Hartig net was not confirmed. These results suggested that the development of ECM-like structures might have occurred spontaneously.

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Mycorrhiza-like Structures in Rooted Microshoots of Pinus pinea L.

Biotization of the mediterranean stone pine (Pinus pinea L.)

Introduction




Basic Techniques




Basal Media




Plant Material




Surface disinfection, Excision of Explants and Culture




Incubation Environment






Clonal Propagation




General Considerations




Organogenesis and Embryogenesis




Strategies for applying SE in Industry




Haploid Culture and Somatic Hybridization




Genetic Engineering






Conclusion




Bibliography





Keywords:

embryogensis;
growth promoters;
culture medium

Cell Procedures, Culture of Conifers

The Genetic Engineering program at Genomica Forestal SA, Chile (GFSA) has a goal of generating stably transformed radiata pine for in planta evaluation of candidate genes. Regeneration of transgenic plants depends mainly on two factors: regeneration ability of transformed cells and stable transgene integration and expression.

In several conifer species, including radiata pine, transgenics have been regenerated through cocultivation of Agrobacterium tumefaciens with embryogenic cells [1-3]. However, in our first experiments using MSG [4] culture medium we found that radiata pine embryonal masses did not recover easily after co cultivation and that there was an excessive overgrowth of bacterial cells in spite of using bacteriostatics in the medium. This impediment prompted our study on testing other culture medium formulations, routinely used in conifer somatic embryogenesis, on the growth of A. tumefaciens GV3101. The tested media were: MSG, DCR [5], and modified Litvay [6] MLV. Of the three media MSG supported significantly higher bacterial growth than the other two media. One of the major differences in the composition of these media is inorganic nitrogen concentration (NH4NO3 and KNO3). Compared with MLV and DCR, MSG has the lowest concentration of inorganic nitrogen (100 mgl-1 compared with 340 in DCR and 950 mgl-l in MLV) provided in the sole form of KNO3. Based on our results and the work of others, we concluded that low nitrate concentration in MSG medium promoted A. tumefaciens growth and this had a deleterious influence on the viability of radiata pine cells during co cultivation, and also rendered eradication of bacterial cells difficult. Comparison of growth of radiata pine embryonal mass on the three media did not show statistically significant differences. A strategy for producing transgenic radiata pine for in planta transgene expression and stability study will be presented.

https://link.springer.com/content/pdf/10.1186/1753-6561-5-S7-P141.pdf

Effect of inorganic nitrogen concentration in co-culture and regeneration media on Agrobacterium tumefaciens growth and on the regenerative capacity of transformed Pinus radiata embryonal mass.

Background Modern forest management relies on extensive breeding and reforestation programs to sustain forest productivity and conservation of natural forests. Plantation forestry, with its increased productivity and improved wood quality, is likely to become an important source of wood products in the future. Vegetative propagation of superior coniferous forest trees through tissue culture has the potential to deliver a stable supply of superior seedlings for forest plantation. To clone adult (mature) conifer trees by means of tissue culture has been a cherished goal for the last several decades. The benefits derived from improving the genetic make-up of planting stock would be significant if such clonal propagation could be achieved at a high efficiency and without growth abnormalities of regenerated plants. Although, somatic embryogenesis (SE) technology has worked well for many conifer species using zygotic embryos as starting material, attempts to achieve the same in adult conifers have failed. The basis of this failure is not exactly understood.

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Krystyna Klimaszewska

Papers

Mycorrhiza-like Structures in Rooted Microshoots of Pinus pinea L.

Biotization of the mediterranean stone pine (Pinus pinea L.)

Cell Procedures, Culture of Conifers

Effect of inorganic nitrogen concentration in co-culture and regeneration media on Agrobacterium tumefaciens growth and on the regenerative capacity of transformed Pinus radiata embryonal mass.

Gene expression in cultured primordial shoots of adult white spruce (Picea glauca) in somatic embryogenesis responsive and non responsive genotypes