Author
Charles L. Armstrong
Other affiliations: University of Minnesota
Bio: Charles L. Armstrong is an academic researcher from Monsanto. The author has contributed to research in topics: Transformation (genetics) & Callus. The author has an hindex of 21, co-authored 36 publications receiving 3768 citations. Previous affiliations of Charles L. Armstrong include University of Minnesota.
Papers
More filters
••
TL;DR: Frequentencies of friable-callus initiation and somatic-embryoid formation increased linearly with addition to N6 medium, and L-Glutamine was not a satisfactory substitute for L-proline.
Abstract: Friable, embryogenic maize (Zea mays L.), inbred line A188, callus was established and maintained for more than one year without apparent loss of friability or embryogenic potential. Embryoid development was abundant in these cultures and plants were easily regenerated. Frequencies of friable-callus initiation and somatic-embryoid formation increased linearly with addition to N6 medium (C.C. Chu et al. 1975, Sci. Sin. [Peking] 18, 659–668) of up to 25 mM L-proline. Proline additions up to 9 mM to MS medium (inorganic elements of T. Murashige and F. Skoog 1962, Physiol. Plant. 15, 473–497, plus 0.5 mg 1-1 thiamine hydrochloride and 150 mg 1-1
L-asparagine monohydrate) did not stimulate embryoid formation. A major part of the difference between MS and N6 media could be attributed to their respective inorganic nitrogen components. L-Glutamine was not a satisfactory substitute for L-proline. Of 111 regenerated plants grown to maturity from three independent friable, embryogenic cell lines ranging in age from three to seven months, only four plants were abnormal based on morphology and pollen sterility. Seed was produced by 77% of the regenerated plants.
1,148 citations
••
TL;DR: Two selectable genes were used to confer resistance to either chlorsulfuron or phosphinothricin, and genes encoding either E. coli β-glucuronidase or firefly luciferase were used as markers to provide convenient assays for transformation.
Abstract: We obtained transgenic maize plants by using high-velocity microprojectiles to transfer genes into embryongenic cells. Two selectable genes were used to confer resistance to either chlorsulfuron or phosphinothricin, and genes encoding either E. coli beta-glucuronidase or firefly luciferase were used as markers to provide convenient assays for transformation. When regenerated without selection, only two of the eight transformed embryogenic calli obtained produced transgenic maize plants. With selection, transgenic plants were obtained from three of the other eight calli. One of the two initial lines produced 15 fertile transgenic plants. The progeny of these plants contained and expressed the foreign genes. Luciferase expression could be visualized, in the presence of added luciferin, by overlaying leaf sections with color film.
649 citations
••
TL;DR: Extension of transformation protocols to elite genotypes and to more readily available explants in agronomically important crop species will be the challenge of the future.
Abstract: Since the success of Agrobacterium-mediated transformation of rice in the early 1990s, significant advances in Agrobacterium-mediated transformation of monocotyledonous plant species have been achieved. Transgenic plants obtained via Agrobacterium-mediated transformation have been regenerated in more than a dozen monocotyledonous species, ranging from the most important cereal crops to ornamental plant species. Efficient transformation protocols for agronomically important cereal crops such as rice, wheat, maize, barley, and sorghum have been developed and transformation for some of these species has become routine. Many factors influencing Agrobacterium-mediated transformation of monocotyledonous plants have been investigated and elucidated. These factors include plant genotype, explant type, Agrobacterium strain, and binary vector. In addition, a wide variety of inoculation and co-culture conditions have been shown to be important for the transformation of monocots. For example, antinecrotic tr...
290 citations
••
TL;DR: A synthetic green fluorescent protein (GFP) gene (pgfp) was constructed to improve GFP expression in plants and produced green fluorescence that was readily detectable by eye using a hand-held, long-wave ultraviolet lamp and/or a black-light source.
Abstract: A synthetic green fluorescent protein (GFP) gene (pgfp) was constructed to improve GFP expression in plants. Corn and tobacco protoplast transient assays showed that pgfp gave about 20-fold brighter fluorescence than the wild-type gene (gfp). Replacement of the serine at position 65 with a threonine (S65Tpgfp) or a cysteine (S65Cpgfp) yielded 100- to 120-fold brighter fluorescence than wild-type gfp upon excitation with 490-nm light. Incorporation of a plant intron into the coding region yielded an additional 1.4-fold improvement, for a cumulative improvement of about 150-fold in fluorescence at 490-nm excitation. Various versions of pgfp were also stably introduced into corn, wheat, tobacco, and Arabidopsis plants. Bright-green fluorescence was observed with a fluorescence microscope in virtually all examined tissues of transgenic monocots and dicots. In the case of Arabidopsis, expression of the pgfp gene under the enhanced 355 promoter of the cauliflower mosaic virus produced green fluorescence that was readily detectable by eye using a hand-held, long-wave ultraviolet lamp and/or a black-light source.
239 citations
••
TL;DR: In this study, microprojectile bombardment was used to introduce synthetic versions of cryIA insecticidal protein genes from Bacillus thuringiensis subsp.
Abstract: The European corn borer [ECB; Ostrinia nubilalis (Hubner)] is an economically significant pest of corn (Zea mays L.). The ability to routinely transform corn has broadened the control options available to include the introduction of resistance genes from sexually incompatible species. In this study, microprojectile bombardment was used to introduce synthetic versions of cryIA insecticidal protein genes from Bacillus thuringiensis subsp. kurstaki (Btk) into embryogenic tissue of the Hi-II (A188/B73 derivative) genotype of corn. Of 715 independent transgenic calli produced, 314 (44%) had insecticidal activity against tobacco hornworm (Manduca sexta L.) larvae. Plants were regenerated, self-pollinated when possible, and crossed to B73. First-generation progeny of 173 independent Btk-protein expressing calli were evaluated under field conditions with artificial ECB infestations in 1992 or 1993. Approximately half (89/173) segregated in a single-gene manner for resistance to first-generation ECB leaf-feeding damage. All of the 89 lines evaluated in 1992 or 1993 for resistance to second-generation ECB exhibited less stalk tunneling damage then the non-transgenic controls. In 1993, 44% (37/77) of the lines tested had ≤ 2.5 cm of tunneling, compared to severe damage (mean = 45.7 cm) in the B73 × Hi-II controls. Experiments are in progress to evaluate the effect of the introduced genes on yield and other agronomic properties
207 citations
Cited by
More filters
••
TL;DR: Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species within normal ranges, thus preventing oxidative burst in plants.
Abstract: When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst ...
1,777 citations
•
08 Jan 2001
TL;DR: In this article, the authors provided an inbred corn plant designated 89AHD12, which was used to produce corn seeds and plants produced by crossing the inbred plant with another corn plant, such as another inbred, and to crosses with related species.
Abstract: According to the invention, there is provided an inbred corn plant designated 89AHD12. This invention thus relates to the plants, seeds and tissue cultures of the inbred corn plant 89AHD12, and to methods for producing a corn plant produced by crossing the inbred corn plant 89AHD12 with itself or with another corn plant, such as another inbred. This invention further relates to corn seeds and plants produced by crossing the inbred plant 89AHD12 with another corn plant, such as another inbred, and to crosses with related species. This invention further relates to the inbred and hybrid genetic complements of the inbred corn plant 89AHD12, and also to the SSR and genetic isozyme typing profiles of inbred corn plant 89AHD12.
1,737 citations
•
21 May 2002
TL;DR: An inbred corn line, designated LH283BtMON810, is disclosed in this paper, which relates to the seeds of the inbred line and to the plants of the line.
Abstract: An inbred corn line, designated LH283BtMON810, is disclosed. The invention relates to the seeds of inbred corn line LH283BtMON810, to the plants of inbred corn line LH283BtMON810 and to methods for producing a corn plant, either inbred or hybrid, by crossing the inbred line LH283BtMON810 with itself or another corn line. The invention further relates to methods for producing a corn plant containing in its genetic material one or more transgenes and to the transgenic plants produced by that method and to methods for producing other inbred corn lines derived from the inbred LH283BtMON810.
1,667 citations
••
TL;DR: It is demonstrated that ingestion of double-stranded (ds)RNAs supplied in an artificial diet triggers RNA interference in several coleopteran species, most notably the western corn rootworm Diabrotica virgifera virgifiera LeConte, suggesting that the RNAi pathway can be exploited to control insect pests via in planta expression of a dsRNA.
Abstract: Commercial biotechnology solutions for controlling lepidopteran and coleopteran insect pests on crops depend on the expression of Bacillus thuringiensis insecticidal proteins1,2, most of which permeabilize the membranes of gut epithelial cells of susceptible insects3 However, insect control strategies involving a different mode of action would be valuable for managing the emergence of insect resistance Toward this end, we demonstrate that ingestion of double-stranded (ds)RNAs supplied in an artificial diet triggers RNA interference in several coleopteran species, most notably the western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte This may result in larval stunting and mortality Transgenic corn plants engineered to express WCR dsRNAs show a significant reduction in WCR feeding damage in a growth chamber assay, suggesting that the RNAi pathway can be exploited to control insect pests via in planta expression of a dsRNA
1,545 citations
••
TL;DR: A set of plasmids has been constructed utilizing the promoter, 5′ untranslated exon, and first intron of the maize ubiquitin (Ubi-1) gene to drive expression of protein coding sequences of choice to provide expression of biotechnologically important protein products in transgenic plants.
Abstract: A set of plasmids has been constructed utilizing the promoter, 5' untranslated exon, and first intron of the maize ubiquitin (Ubi-1) gene to drive expression of protein coding sequences of choice. Plasmids containing chimaeric genes for ubiquitin-luciferase (Ubi-Luc), ubiquitin-beta-glucuronidase (Ubi-GUS), and ubiquitin-phosphinothricin acetyl transferase (Ubi-bar) have been generated, as well as a construct containing chimaeric genes for both Ubi-GUS and Ubi-bar in a single plasmid. Another construct was generated to allow cloning of protein coding sequences of choice on Bam HI and Bam HI-compatible restriction fragments downstream of the Ubi-1 gene fragment. Because the Ubi-1 promoter has been shown to be highly active in monocots, these constructs may be useful for generating high-level gene expression of selectable markers to facilitate efficient transformation of monocots, to drive expression of reference reporter genes in studies of gene expression, and to provide expression of biotechnologically important protein products in transgenic plants.
1,224 citations