HPPD Enzyme Mutations for Herbicide Tolerance
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Solution Overview
Problem
Current methods for developing plants tolerant to HPPD inhibitor herbicides, particularly those belonging to the triketones and pyrazolinates classes, are inadequate, as existing strategies do not provide sufficient tolerance for post-emergence treatments and lack effective mechanisms for newer herbicides.
Innovation Solution
Generation of transgenic plants containing genes encoding HPPD proteins from Synechococcus species, which exhibit high amino acid sequence identity and specific mutations, conferring reduced sensitivity to HPPD inhibitors, thereby enhancing herbicide tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing HPPD gene strategies are used to confer herbicide tolerance, then some tolerance is achieved, but sufficient tolerance for post-emergence treatments is not provided
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid mutations at positions 145, 169, 170, 172, 181, 184, 186, 187, 244, 281, 327, and 328 in the HPPD protein sequence. These mutations alter the enzymatic parameters and herbicide binding characteristics, conferring reduced sensitivity to HPPD inhibitor herbicides and enabling effective post-emergence treatment tolerance.
2Reliability
If conventional HPPD proteins are expressed in plants, then some enzymatic activity is achieved, but tolerance to newer HPPD inhibitors like triketones and pyrazolinates is insufficient
Solution Approach 1:
The patent achieves universality by creating an HPPD protein variant through multiple amino acid substitutions that provides broad-spectrum tolerance across different herbicide classes including triketones (e.g., tembotrione, mesotrione), pyrazolinates (e.g., topramezone, pyrasulfotole), and other HPPD inhibitors. The mutated protein structure allows it to resist binding by diverse herbicide molecules, enabling a single genetic modification to confer versatility against multiple herbicide types.
3Object-affected harmful factors
If HPPD inhibitor herbicides are applied to conventional plants, then weed control is achieved, but plant growth inhibition and death occur due to lack of tolerance
Solution Approach 1:
The patent converts the harmful effect of HPPD inhibitor herbicides into a beneficial outcome by introducing specific amino acid mutations in the HPPD protein. These mutations alter the enzyme's structure to prevent herbicide binding while maintaining enzymatic function, thereby converting what would be a harmful toxic effect into a selective advantage that protects the plant from growth inhibition and death while allowing effective weed control.
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 transgenic plants demonstrate improved tolerance to HPPD inhibitor herbicides, including triketones and pyrazolinates, particularly tembotrione, mesotrione, and bicyclopyrone, both pre- and post-emergence, by maintaining enzymatic activity and reducing herbicide sensitivity.
Implementation Method 1
The HPPDs are enzymes which catalyse the reaction in which para-hydroxyphenylpyruvate (abbreviated herein as HPP), a tyrosine degradation product, is transformed into homogentisate (abbreviated herein as HG)
Implementation Method 2
Inhibition of HPPD leads to uncoupling of photosynthesis, deficiency in accessory light-harvesting pigments and, most importantly, to destruction of chlorophyll by UV-radiation and reactive oxygen species (bleaching) due to the lack of photo protection normally provided by carotenoids
Data Source
AI summary
The present invention relates to nucleic acid sequences encoding a hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27, abbreviated herein as HPPD) obtained from bacteria belonging to the subfamily Synechococcoideae, as well as the proteins encoded thereby, and to a chimeric gene which comprises such nucleic acid sequence, and to the use of such nucleic acid sequences, proteins or chimeric genes for obtaining plants which are tolerant to HPPD inhibitor herbicides.