Selectable Markers and Promoters for Environmentally Friendly Plant Tissue Culture Transformation
- Detailed Technology Description
- This DNA-based technology provides a novel, selectable marker gene and promoter for producing transgenic plants with heightened levels of tryptophan (Trp). Specifically, it includes a tobacco-derived gene for a variant of the enzyme anthranilate synthase (AS). This technology encompasses the gene (ASA2) and its promoter, and is capable of directing tissue culture-specific transcription of a downstream structural gene in plant cells. Relevant methods and transformed, regenerated plants are included in the technology.
- Countries
- United States
- Application No.
- 6563025
- *Abstract
-
This DNA-based technology provides a novel, selectable marker gene and promoter for producing transgenic plants with heightened levels of tryptophan (Trp). Specifically, it includes a tobacco-derived gene for a variant of the enzyme anthranilate synthase (AS). This technology encompasses the gene (ASA2) and its promoter, and is capable of directing tissue culture-specific transcription of a downstream structural gene in plant cells. Relevant methods and transformed, regenerated plants are included in the technology.
DESCRIPTION/DETAILS
A goal of plant genetic engineering has been the creation of nutritionally superior food crops for humans and domestic animals. Improvement in amino acid composition of seed proteins is a major target, since neither animals nor humans can synthesize certain amino acids (e.g., Trp) needed for protein synthesis and must obtain them from the diet. Advances in plant tissue culture techniques and gene transfer technology provide opportunities to modify plant amino acid content.
This technology enables genetic modification of plants for nutritional purposes, provides new expression vehicles for additional plant genes, and negates expression of a transformation marker gene product in transformed plants an environmentally friendly characteristic.
How It Works
The gene for AS, a crucial enzyme in Trp biosynthesis, has been used as a selectable marker for amino acid analog-resistance in transformed plants. This novel DNA construct technology uses an AS-based marker to select for transformed (versus nontransformed) plant cells following transformation experiments, based on their newly obtained resistance to a growth inhibitor, 5-methyltryptophan (5MT).
Transformed cells generate elevated levels of Trp and survive, a capacity they would lack without expression of the marker a feedback-insensitive gene for AS (the tobacco-derived ASA2 gene). An additional plant gene, (i.e., one encoding a valuable trait) can be engineered into the DNA construct (a plasmid) containing the marker gene in close enough proximity to virtually ensure their simultaneous integration into plant cell DNA.
Both the marker gene and the desired gene may have their own promoters, and their linear order on the construct is not expected to be relevant since each gene is controlled by its own promoter and terminator. Specifically, this technology provides DNA contructs containing the ASA2 promoter and the ASA2 structural gene. Accommodation of another gene, one not operatively associated with the ASA2 promoter, is feasible, as mentioned above. The novel, engineered promoter sequences of these constructs have the ability to preferentially express the marker gene (ASA2) only in tissue culture and not in any resultant, regenerated plants. An additional feature of this technology is the ability to identify and manipulate any plants regenerated from transformed cells. It applies a method for altering the Trp content of a plant by transforming the plant cells with an expression cassette containing the ASA2 structural gene and a method for producing AS.
The technology also includes a method for selecting transformed plant cells by use of the expression cassette. Finally, regenerated, transformed plants and plant cells derived from use of these DNA constructs are also included.
Why It Is Better
With prior DNA constructs, the selectable marker gene would be expressed in all cultured, transformed plant cells, as well as any regenerated plants arising from them. Much environmental concern has arisen over this property because most selectable markers are constitutively expressed in all tissues of the plant and do not originate from plants. However, the promoter sequences of these constructs not only arise from plants but have the ability to preferentially express genes only in tissue culture, and not in any resultant, regenerated plants.
This novel and improved method for enhancing plant nutritional value will allay environmental concerns associated with genetically engineered plants. This new approach presents a valuable method for increased control over environmental impacts, and offers a simple solution to concerns of both the government and the general public.
APPLICATIONS
- Plant biotechnology research (e.g., plant gene expression)
- Agricultural food-crop production (e.g., Trp-supplemented grains)
- Plant husbandry (e.g., genetic enhancement of nonfood crop plants)
BENEFITS
This invention will benefit scientists attempting to improve the nutritional value of plants, as well as allay environmental concerns associated with genetically engineered plants.
- Potentially enhanced nutritional content of grain crops for human (or animal) consumption, via enhanced Trp production
- Diminished environmental concerns regarding constitutive expression of selectable markers in transformed plants, via engineered promoters that provide preferential transcription of associated marker DNA sequences in tissue culture rather than in transformed plants
- Reduced potential for negative environmental impacts from genetically engineered plants transformed with nonplant genes, given the engineered transcription of a plant marker gene.
- Potential environmental superiority due to the plant-derived (versus bacteria-derived) origins of the long-standing AS marker gene and its promoter
For more information about this technology, please contact the University of Illinois at Urbana-Champaign Office of Technology Management at otm@illinois.edu.
- *IP Issue Date
- None
- *IP Type
- Utility
- Country/Region
- USA
