Soybean HPPD Downregulation via dsRNA for Herbicide Tolerance
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Solution Overview
Problem
Current methods for conferring tolerance to HPPD inhibitor herbicides in plants are inadequate, particularly for newer herbicides like triketones, pyrazolinates, and N-(1,2,5-oxadiazol-3-yl)benzamides, as existing strategies do not provide sufficient agronomic tolerance levels.
Innovation Solution
The use of double-stranded ribonucleic acid (dsRNA) targeting endogenous HPPD genes, combined with expression of mutant HPPD enzymes derived from Pseudomonas fluorescens, to downregulate HPPD activity in soybeans, thereby enhancing tolerance to HPPD inhibitor herbicides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HPPD enzyme activity is increased to compensate for herbicide inhibition, then plant growth and photosynthesis are maintained, but the plant becomes more sensitive to HPPD inhibitor herbicides
Solution Approach 1:
Instead of overexpressing HPPD to increase tolerance (conventional approach), the patent downregulates HPPD expression using RNAi technology. This inverse strategy reduces the enzyme's vulnerability to herbicide inhibition while maintaining sufficient activity through alternative pathways, thereby achieving herbicide tolerance.
Solution Approach 2:
The patent changes the expression level parameter of HPPD from high/normal to reduced levels. By modulating the expression quantity of HPPD gene through RNAi, the plant achieves a new balance where herbicide tolerance is improved without compromising essential physiological functions.
2Reliability
If HPPD expression is downregulated to confer herbicide tolerance, then herbicide resistance is improved, but photosynthetic function may be compromised
Solution Approach 1:
The patent introduces alternative metabolic pathways as intermediaries to compensate for reduced HPPD activity. These alternative pathways provide sufficient homogentisate production to maintain photosynthetic function while the primary HPPD pathway remains downregulated for herbicide tolerance.
Solution Approach 2:
The patent applies partial downregulation of HPPD expression rather than complete knockout. This partial action maintains sufficient enzyme activity for essential physiological functions while achieving adequate herbicide tolerance, avoiding the excessive reduction that would compromise photosynthesis.
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
This approach significantly improves soybean tolerance to HPPD inhibitor herbicides, allowing for increased resistance and reduced damage from herbicide applications, enhancing agronomic performance.
Implementation Method 1
The use of double-stranded ribonucleic acid (dsRNA) targeting endogenous HPPD genes, combined with expression of mutant HPPD enzymes derived from Pseudomonas fluorescens, to downregulate HPPD activity in soybeans
Implementation Method 2
The 4-hydroxyphenylpyruvate dioxygenases (HPPDs) are enzymes which catalyze the reaction in which para-hydroxyphenylpyruvate (abbreviated herein as HPP), a tyrosine degradation product, is transformed into homogentisate (abbreviated herein as HG)
Data Source
AI summary
A method for conferring tolerance to a 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor herbicide in a plant includes reducing expression of at least one HPPD enzyme in the plant.