HCEM485 Cisgenic Maize Event for Stable Glyphosate Tolerance
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Solution Overview
Problem
The challenge lies in developing glyphosate-tolerant maize plants with stable and optimal expression of transgenes, as existing methods face variability in expression levels and patterns, affecting breeding efficiency and the need for extensive screening to identify desirable traits.
Innovation Solution
The development of cisgenic glyphosate-tolerant maize plants, specifically the HCEM485 event, which includes a maize genomic DNA fragment with an EPSPS 5' regulatory sequence and a coding sequence encoding a glyphosate-resistant EPSPS, introduced into the chloroplast, providing tolerance through specific mutations, and utilizing molecular markers for tracking and breeding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recombinant DNA technology is used to introduce glyphosate-resistant EPSPS genes into maize, then glyphosate tolerance is achieved, but expression levels and patterns vary significantly across different events
Solution Approach 1:
The patent applies parameter changes by modifying the EPSPS gene sequence to create specific mutations (such as Pro198Ser and Thr102Ile) that alter the enzyme's properties. These parameter changes in the gene sequence result in an EPSPS variant with increased glyphosate resistance while maintaining stable and predictable expression levels across different transformation events, resolving the contradiction between achieving tolerance and maintaining expression precision.
2Manufacturing precision
If multiple transformation events are screened to identify optimal expression, then desirable transgene expression is achieved, but breeding efficiency decreases and time increases
Solution Approach 1:
The patent applies preliminary action by pre-selecting and characterizing specific EPSPS mutation events (such as the double mutant with Pro198Ser and Thr102Ile) that have been proven to exhibit stable and optimal expression patterns. By establishing these pre-characterized events, the patent eliminates the need for extensive screening of multiple transformation events, thereby improving breeding efficiency while ensuring desirable expression levels are achieved.
3Adaptability or versatility
If transgenes are introduced at different genomic locations, then integration variability occurs, but expression consistency is compromised
Solution Approach 1:
The patent applies parameter changes by introducing specific mutations in the EPSPS gene (such as Pro198Ser and Thr102Ile) that fundamentally alter the enzyme's properties. These parameter changes result in an EPSPS variant whose expression is less sensitive to genomic location variations, thereby maintaining stable expression patterns even when integrated at different chromosomal sites, thus resolving the contradiction between integration variability and expression consistency.
Data Source
AI summary
Maize event HCEM485 is provided, in which plants comprising the event are tolerant to exposure to a glyphosate herbicide. Maize genomic polynucleotides flanking the insert DNA providing glyphosate tolerance are provided. The plant or part thereof having the event comprises a junction region of the insert DNA and maize plant genomic sequences. Methods and primers and probes to detect the presence of the event are provided, as well as kits which employ such primers and probes.