Mutant HPPD Polypeptides for Broad-Spectrum Herbicide Resistance
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Solution Overview
Problem
Current methods for conferring herbicide tolerance to plants using mutant hydroxyphenyl pyruvate dioxygenase (HPPD) enzymes are inadequate for providing commercial levels of resistance to different classes of HPPD-inhibiting herbicides, as they often fail to offer sufficient tolerance across various herbicides, affecting weed control, manufacturing costs, and environmental impact.
Innovation Solution
Development of mutant HPPD polypeptides with specific amino acid substitutions and deletions that maintain enzymatic activity, allowing plants to be less sensitive to HPPD-inhibiting herbicides, thereby conferring resistance or tolerance by introducing nucleotide sequences encoding these mutant polypeptides into plants through expression cassettes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mutant HPPD enzymes are used to confer herbicide tolerance, then resistance to some HPPD-inhibitor herbicides is achieved, but tolerance to different, more desirable HPPD-inhibitor herbicides is inadequate
Solution Approach 1:
The patent applies parameter changes by creating multiple variants of the HPPD enzyme with different amino acid sequences (e.g., L254F, L254S, L254A, L254V, L254T, L254G, L254P, L254H, L254R, L254K, L254Q, L254E, L254D, L254C, L254M, L254I, L254L, L254N, L254W, L254Y, L254X, L254Z, L254O, L254U, L254J, L254B, L254A, L254G, L254P, L254H, L254R, L254K, L254Q, L254E, L254D, L254C, L254M, L254I, L254L, L254N, L254W, L254Y, L254X, L254Z, L254O, L254U, L254J, L254B) to achieve varying degrees of tolerance across different herbicide classes. This allows the enzyme to adapt its binding characteristics to different herbicide molecules, thereby expanding the spectrum of effective weed control while maintaining crop safety.
2Quantity of substance
If HPPD enzyme is overexpressed to produce sufficient quantities, then functional enzyme availability is increased, but the approach is inadequate for commercial levels of tolerance to different herbicide classes
Solution Approach 1:
Instead of merely increasing enzyme quantity through overexpression, the patent changes the enzyme's molecular parameters by introducing specific amino acid substitutions at critical positions (such as L254F, L254S, L254A, etc.). These parameter changes alter the enzyme's binding affinity and catalytic properties, enabling it to maintain effective function even in the presence of higher concentrations of diverse HPPD-inhibiting herbicides, thereby achieving reliable commercial-level tolerance.
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 mutant HPPD polypeptides provide enhanced tolerance to specific classes of HPPD-inhibiting herbicides, enabling plants to require higher herbicide doses for damage, thus reducing yield impact and increasing herbicide resistance, effectively addressing the limitations of existing tolerance methods.
Implementation Method 1
The hydroxyphenylpyruvate dioxygenases (HPPDs) are enzymes that catalyze the reaction in which para-hydroxyphenylpyruvate (HPP) is transformed into homogentisate
Implementation Method 2
This reaction takes place in the presence of enzyme-bound iron (Fe 2+via the photo-generation of singlet oxygen
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Compositions and methods for conferring hydroxyphenyl pyruvate dioxygenase (HPPD) herbicide resistance or tolerance to plants are provided. Compositions include amino acid sequences, and variants and fragments thereof, for mutant HPPD polypeptides. Nucleic acids that encode the mutant HPPD polypeptides are also provided. Methods for conferring herbicide resistance or tolerance, particularly resistance or tolerance to certain classes of herbicides that inhibit HPPD, in plants are further provided. Methods are also provided for selectively controlling weeds in a field at a crop locus and for the assay, characterization, identification and selection of the mutant HPPDs of the current invention that provide herbicide tolerance.