Alopecurus PPO Enzyme Mutations for Herbicide Tolerance
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Solution Overview
Problem
Current methods do not provide crop plants with broad-spectrum tolerance to PPO-inhibiting herbicides, limiting their effectiveness in weed control and crop protection.
Innovation Solution
Transgenic plants are developed by increasing the activity of wildtype or mutant Alopecurus myosuroides PPO polypeptides or their homologs, which confer increased tolerance to a wide variety of PPO-inhibiting herbicides through over-expression or mutation, allowing for the use of these herbicides near crop plants without harming them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional herbicide application methods are used, then weed control effectiveness is achieved, but crop plants are harmed by the herbicides
Solution Approach 1:
The patent applies parameter changes by modifying the PPO enzyme through site-directed mutagenesis at specific amino acid positions (128, 420, and 587). These molecular parameter changes create a herbicide-resistant PPO variant that can withstand PPO-inhibiting herbicides while maintaining catalytic function, thereby protecting crop plants from herbicide harm while preserving weed control effectiveness.
Solution Approach 2:
The patent uses a engineered PPO protein as an intermediary substance that mediates between the herbicide and the plant's metabolic system. This modified PPO enzyme acts as a protective intermediary that binds to herbicides without being inhibited, neutralizing their harmful effects while allowing the plant to maintain normal protoporphyrinogen oxidation function.
2Adaptability or versatility
If herbicide-resistant PPO variants are introduced, then broad-spectrum herbicide tolerance is achieved, but the complexity of plant genetic modification increases
Solution Approach 1:
The patent achieves universality by engineering a PPO variant with broad-spectrum resistance against multiple classes of PPO-inhibiting herbicides (diphenylethers, oxidiazoles, cyclic imides, phenyl pyrazoles, pyridine derivatives, and phenopylate analogs). The single modified PPO protein performs the universal function of catalyzing protoporphyrinogen oxidation while resisting diverse herbicide structures, eliminating the need for multiple different resistance mechanisms.
Solution Approach 2:
The patent applies parameter changes through site-directed mutagenesis at three specific amino acid positions (128, 420, and 587) in the PPO protein sequence. These targeted parameter changes in the enzyme's active site create steric and electronic modifications that provide broad-spectrum herbicide tolerance while maintaining catalytic function, achieving versatility through precise molecular parameter adjustment rather than complex genetic restructuring.
3Reliability
If multiple PPO mutations are introduced, then resistance to multiple herbicide classes is achieved, but the difficulty of developing and regulating transgenic plants increases
Solution Approach 1:
The patent applies preliminary action by pre-engineering the PPO protein with all three necessary mutations (at positions 128, 420, and 587) incorporated into a single gene construct before introduction into the plant. This preliminary genetic modification ensures that the plant receives a complete, pre-assembled resistance mechanism in one transformation event, rather than requiring multiple sequential breeding steps or gene stacking operations to achieve the same multi-class herbicide resistance.
Data Source
AI summary
The invention refers to plants comprising wild-type or mutated Alopecurus PPO enzymes, and methods of obtaining such plants. The present invention further refers to a method for controlling weeds at a plant cultivation site, the method comprising the steps of providing, at said site, a plant that comprises at least one nucleic acid comprising a nucleotide sequence encoding a wild-type or a mutated Alopecurus PPO enzyme which is resistant or tolerant to a PPO-inhibiting herbicide by applying to said site an effective amount of said herbicide.