Plant Herbicide Tolerance via Prephenate Dehydrogenase and HPPD Overexpression
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Solution Overview
Problem
Current methods for making plants tolerant to HPPD-inhibiting herbicides are limited in their ability to increase prenylquinone biosynthesis and herbicide tolerance, as they primarily focus on detoxification or mutation of target enzymes, without effectively leveraging the shikimate pathway for enhanced precursor flux.
Innovation Solution
The transformation of plants with a gene encoding a prephenate dehydrogenase (PDH) enzyme, which connects the prenylquinone biosynthesis to the shikimate pathway, combined with overexpression of an HPPD enzyme, significantly increases the flux of HPP precursor and tolerance to HPPD inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plants are transformed with HPPD-inhibiting herbicides for tolerance, then herbicide tolerance is improved, but prenymlquinone biosynthesis is limited
Solution Approach 1:
The patent introduces a PDH gene before HPPD inhibition occurs, establishing an alternative pathway that preps HPP precursor availability in advance. This preliminary genetic modification ensures that when HPPD is inhibited by herbicides, the plant already has accumulated precursors and alternative routes to maintain prenylquinone biosynthesis, thus resolving the contradiction between herbicide tolerance and biosynthesis productivity
Solution Approach 2:
The PDH enzyme acts as an intermediary that bridges the shikimate pathway and prenymlquinone biosynthesis. By introducing PDH from yeast or bacteria, the patent creates a mediating enzyme that converts prephenate to HPP, bypassing the blocked HPPD step and maintaining flux through the pathway even when HPPD is inhibited by herbicides
2Object-affected harmful factors
If detoxification methods are used for herbicide tolerance, then herbicide sensitivity is reduced, but precursor flux through shikimate pathway is not enhanced
Solution Approach 1:
Instead of waiting for herbicide detoxification after damage occurs, the patent preliminarily introduces PDH to establish an alternative biosynthetic route before herbicide exposure. This proactive approach not only reduces herbicide sensitivity but also preliminarily enhances precursor flux by creating an additional pathway that operates independently of HPPD
Solution Approach 2:
The patent segments the prenymlquinone biosynthesis pathway by introducing PDH as a separate, independent enzymatic step that bypasses the HPPD blockage. This segmentation allows the pathway to be divided into two independent routes: one through HPPD (blocked by herbicides) and one through PDH (unaffected), thereby maintaining overall pathway productivity while reducing herbicide sensitivity
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 results in plants that produce significantly higher levels of prenylquinones, such as tocopherols and tocotrienols, and exhibit enhanced tolerance to HPPD-inhibiting herbicides, making them more resistant to herbicides like isoxazoles and triketones.
Implementation Method 1
prephenate dehydrogenase (hereinafter referred to as PDH), which converts prephenate to HPP
Implementation Method 2
HPPD enzyme, which converts HPP to homogentisate
Implementation Method 3
transformed plants producing larger amounts of plastoquinones, tocotrienols and tocopherols
Data Source
AI summary
The present invention relates to transformed plants, in particular transformed plants producing larger amounts of plastoquinones, tocotrienols and tocopherols than non-transformed identical plants. This invention also relates to a method for producing these plants, and to a method for cultivating these plants. The plants according to the invention also have the property of being tolerant to herbicides that are inhibitors of the p-hydroxyphenylpyruvate dioxygenase enzyme.