Production of transgenic maize plants and progeny by bombardment of hi-II immature embryos

Songstad, D. D.; Armstrong, Charles; Petersen, William L.; Hairston, B.; Hinchee, Maud A. W.

doi:10.1007/bf02822763

Cited by 79 publications

(44 citation statements)

References 21 publications

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“…Here, using the transcription factors Bbm and Wus2, we demonstrated that cells in the exposed embryo axis of mature maize seed can reproducibly produce transgenic callus and regenerate healthy, fertile T0 plants. In contrast to scutellum transformation typically observed for immature embryo transformation (Songstad et al, 1996), we never observed transgenic events originating from the mature scutellum of maize embryos. The simplest explanation for this difference is that the Agrobacterium strain used in our experiments for mature embryo transformation predominantly delivered DNA into cells of the embryo axis and not the scutellum ( Figure 5C).…”

Section: Discussioncontrasting

confidence: 95%

“…For monocots, there has been a progression from particle gun transformation to that mediated by Agrobacterium tumefaciens, as well as refinements in tissue culture protocols and selection strategies (Shrawat and Lörz, 2006). Since the earliest reports of maize protoplast transformation (Rhodes et al, 1988;Shillito et al, 1989;Golovkin et al, 1993), the preferred target cells for transformation have gone from maize cells in liquid suspension (Fromm et al, 1990;Gordon-Kamm et al, 1990;Frame et al, 1994), through embryogenic callus (Walters et al, 1992;Wan et al, 1995), and finally to the transformation of scutellar cells of freshly isolated immature embryos (Ishida et al, 1996;Songstad et al, 1996;Frame et al, 2002). For other monocots such as barley (Hordeum vulgare), wheat, rice, and sorghum, immature embryos remain the predominant transformation target, despite reports over the years of successfully initiating tissue culture responses from explants other than immature embryos.…”

Section: Introductionmentioning

confidence: 99%

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Morphogenic Regulators Baby boom and Wuschel Improve Monocot Transformation

et al. 2016

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While transformation of the major monocot crops is currently possible, the process typically remains confined to one or two genotypes per species, often with poor agronomics, and efficiencies that place these methods beyond the reach of most academic laboratories. Here, we report a transformation approach involving overexpression of the maize (Zea mays) Baby boom (Bbm) and maize Wuschel2 (Wus2) genes, which produced high transformation frequencies in numerous previously nontransformable maize inbred lines. For example, the Pioneer inbred PHH5G is recalcitrant to biolistic and Agrobacterium tumefaciens transformation. However, when Bbm and Wus2 were expressed, transgenic calli were recovered from over 40% of the starting explants, with most producing healthy, fertile plants. Another limitation for many monocots is the intensive labor and greenhouse space required to supply immature embryos for transformation. This problem could be alleviated using alternative target tissues that could be supplied consistently with automated preparation. As a major step toward this objective, we transformed Bbm and Wus2 directly into either embryo slices from mature seed or leaf segments from seedlings in a variety of Pioneer inbred lines, routinely recovering healthy, fertile T0 plants. Finally, we demonstrated that the maize Bbm and Wus2 genes stimulate transformation in sorghum (Sorghum bicolor) immature embryos, sugarcane (Saccharum officinarum) callus, and indica rice (Oryza sativa ssp indica) callus.

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Section: Discussioncontrasting

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Morphogenic Regulators Baby boom and Wuschel Improve Monocot Transformation

et al. 2016

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“…Agrobacterium-mediated transformation with pWY76 and pWY86 was performed as described (7). Biolistic-mediated gene transformation of maize immature embryos was conducted as described (42,43).…”

Section: Methodsmentioning

confidence: 99%

Construction and behavior of engineered minichromosomes in maize

Han

Gao

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

137

138

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Engineered minichromosomes were constructed in maize by modifying natural A and supernumerary B chromosomes. By using telomere-mediated chromosomal truncation, it was demonstrated that such an approach is feasible for the generation of minichromosomes of normal A chromosomes by selection of spontaneous polyploid events that compensate for the deficiencies produced. B chromosomes are readily fractionated by biolistic transformation of truncating plasmids. Foreign genes were faithfully expressed from integrations into normal B chromosomes and from truncated miniB chromosomes. Site-specific recombination between the terminal transgene on a miniA chromosome and a terminal site on a normal chromosome was demonstrated. It was also found that the miniA chromosome did not pair with its progenitor chromosomes during meiosis, indicating a useful property for such constructs. The miniB chromosomes are faithfully transmitted from one generation to the next but can be changed in dosage in the presence of normal B chromosomes. This approach for construction of engineered chromosomes can be easily extended to other plant species because it does not rely on cloned centromere sequences, which are species-specific. These platforms will provide avenues for studies on plant chromosome structure and function and for future developments in biotechnology and agriculture.artificial chromosomes ͉ FISH ͉ genetic engineering ͉ telomere truncation A rtificial chromosomes involving de novo centromere formation on an independently assembled unit and engineered minichromosomes produced by telomere truncation provide striking advantages over traditional methods of gene transformation in yeast and mammalian cells (1-5). The development of such chromosomes in plants would provide these advantages for many applications in basic studies, biotechnology, and agriculture. These chromosomes could be used as independent platforms for foreign gene expression without random integration into the normal chromosomes. Further additions of unlimited amounts of DNA could be added to these platforms in a sequential manner via different site-specific recombination cassettes. Genes introduced in this way would be present in a defined context and thus could be expressed at a more predictable level than through random integration (6). Hence, additional genes, multigene complexes, or even whole metabolic pathways could potentially be added to a genotype. Moreover, engineered or artificial chromosomes could be easily introduced or removed from a genotype by genetic crosses and would facilitate introgression of transgenes to different genetic backgrounds.To extend engineered chromosome technology to plants, we developed a method of telomere-mediated chromosomal truncation in maize by Agrobacterium-mediated transformation of constructs with multiple copies of the telomere sequence (7). Here, we report the use of this technology to produce minichromosome platforms by truncating both normal A and supernumerary B maize chromosomes and at the same time introducing site-spe...

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“…Particle-mediated transformation was performed as described by Songstad et al (1996). After incubating the embryos on 560P medium in the dark at 28°C for 4 or 5 d, they were transferred onto 560Y medium and subcultured scutellum side up for 3 h before transformation.…”

mentioning

confidence: 99%

Cyclin-Dependent Kinase Inhibitors in Maize Endosperm and Their Potential Role in Endoreduplication

et al. 2005

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Two maize (Zea mays) cyclin-dependent kinase (CDK) inhibitors, Zeama;KRP;1 and Zeama;KRP;2, were characterized and shown to be expressed in developing endosperm. Similar to the CDK inhibitors in Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum), the maize proteins contain a carboxy-terminal region related to the inhibitory domain of the mammalian Cip/Kip inhibitors. Zeama;KRP;1 is present in the endosperm between 7 and 21 d after pollination, a period that encompasses the onset of endoreduplication, while the Zeama;KRP;2 protein declines during this time. Nevertheless, Zeama;KRP;1 accounts for only part of the CDK inhibitory activity that peaks coincident with the endoreduplication phase of endosperm development. In vitro assays showed that Zeama;KRP;1 and Zeama;KRP;2 are able to inhibit endosperm Cdc2-related CKD activity that associates with p13Suc1. They were also shown to specifically inhibit cyclin A1;3- and cyclin D5;1-associated CDK activities, but not cyclin B1;3/CDK. Overexpression of Zeama;KRP;1 in maize embryonic calli that ectopically expressed the wheat dwarf virus RepA protein, which counteracts retinoblastoma-related protein function, led to an additional round of DNA replication without nuclear division.

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Production of transgenic maize plants and progeny by bombardment of hi-II immature embryos

Cited by 79 publications

References 21 publications

Morphogenic Regulators Baby boom and Wuschel Improve Monocot Transformation

Morphogenic Regulators Baby boom and Wuschel Improve Monocot Transformation

Construction and behavior of engineered minichromosomes in maize

Cyclin-Dependent Kinase Inhibitors in Maize Endosperm and Their Potential Role in Endoreduplication

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