Modified Class I EPSPS Genes Glyphosate Tolerance
Solution Overview
Problem
There is a need for diverse genes that provide herbicide resistance in plants, particularly for glyphosate, to enable effective weed control with minimal crop damage, and existing technologies lack sufficient selectable marker phenotypes for plant molecular biology applications.
Innovation Solution
Development of modified Class I EPSPS genes with specific amino acid substitutions, such as aspartic acid at position 68 and isoleucine or leucine at position 102, or glutamic acid at position 68 and cysteine at position 101, which confer glyphosate tolerance, allowing for the creation of transgenic plants resistant to glyphosate herbicide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type EPSPS genes are used in plants, then the plants can perform normal shikimate pathway function, but the plants are highly sensitive to glyphosate and cannot survive herbicide applications
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of the EPSPS protein at specific positions (such as replacing threonine with isoleucine or leucine at position 102, and proline with alanine or threonine at position 106). These parameter changes in the protein structure alter the binding affinity for glyphosate, reducing inhibition while maintaining catalytic activity, thereby conferring glyphosate tolerance to the plant.
Solution Approach 2:
The patent applies local quality by making specific localized modifications at particular amino acid positions within the EPSPS protein sequence rather than altering the entire protein. The modifications are focused on specific residues (e.g., positions 102, 106, 68, 167) that are critical for glyphosate binding, allowing the rest of the protein to maintain its native function while the modified local regions provide resistance.
2Reliability
If modified EPSPS genes with amino acid substitutions are introduced to provide glyphosate tolerance, then the plants can withstand glyphosate applications, but the genetic diversity of selectable marker phenotypes remains limited
Solution Approach 1:
The patent applies universality by developing a family of EPSPS variants with different amino acid substitutions at multiple positions that all confer glyphosate tolerance. These variants can be used across different plant species and transformation systems, providing a universal selectable marker system. The modified genes can be combined with various promoters and expression cassettes, making them broadly applicable for plant molecular biology applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified EPSPS genes enable the production of glyphosate-tolerant plants, serving as selectable markers and facilitating effective weed control by allowing crop plants to withstand glyphosate applications without damage.
Implementation Method 1
EPSPS enzymes are broadly categorized into three groups: Class I, Class II and Class Ill. Mutations in Class I EPSPS genes are known that provide tolerance to glyphosate's inhibitory activity. For example, Glyphosate tolerance in plants can be achieved by the expression of a modified Class I EPSPS that has lower affinity for glyphosate, yet still retains its catalytic activity in the presence of glyphosate
Implementation Method 2
The present invention provides DNA and protein compositions of a glyphosate tolerant variant Class I EPSPS enzyme. The present invention also provides DNA constructs useful in plants and transgenic plants that exhibit glyphosate tolerance.
Data Source
AI summary
The present invention relates to DNA molecules encoding glyphosate tolerant mutant EPSPS enzymes as well as constructs and plants comprising said enzymes. Also included are methods of using said enzymes, including use as a selectable marker, use to make transgenic plants resistant to glyphosate containing herbicides and methods of controlling weeds.