AO2 Gene Mutation for Low Alkaloid Tobacco
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Solution Overview
Problem
Current methods for producing tobacco with extremely low nicotine content require mutation or suppressed expression of a large number of genes, leading to undesired characters such as malformation and early senescence. There is no example of a tobacco plant with extremely low nicotine content achieved by mutating only one or two enzyme genes.
Innovation Solution
A tobacco plant is developed where the function of a single AO2 gene, which is root-specific aspartate oxidase, is suppressed by a mutation inherent in the AO2 gene, resulting in a significantly reduced alkaloid content. This is achieved by introducing a mutation in the AO2 gene in diploid tobacco plants or in both AO2-S and AO2-T genes in amphidiploid tobacco plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large number of genes are mutated or suppressed to achieve extremely low nicotine content, then nicotine content is reduced, but the plant exhibits undesired characters such as malformation and early senescence
Solution Approach 1:
The invention extracts and targets only the essential enzyme genes required for nicotine biosynthesis (AO, PMT, BBL) for mutation, rather than mutating a large number of genes. This selective approach removes only the necessary components for nicotine production while preserving the rest of the plant's genetic integrity and health.
Solution Approach 2:
The invention applies mutation specifically to localized enzyme genes involved in nicotine biosynthesis pathways (AO, PMT, BBL) rather than throughout the entire genome. This localized genetic modification achieves nicotine reduction while maintaining normal plant development and preventing system-wide adverse effects.
2Quantity of substance
If multiple enzyme genes are mutated to achieve low nicotine content, then nicotine biosynthesis is suppressed, but the breeding process becomes complex and difficult to implement
Solution Approach 1:
The invention identifies a small set of universal key enzyme genes (AO, PMT, BBL) that are essential for nicotine biosynthesis. By targeting these few multi-functional genes that control the entire nicotine production pathway, the invention simplifies the breeding process while achieving effective nicotine reduction.
Solution Approach 2:
The invention changes the genetic parameters by mutating specific enzyme genes (AO, PMT, BBL) involved in nicotine biosynthesis. This targeted parameter change approach reduces nicotine content through controlled genetic modification of key pathway enzymes, making the breeding process more manageable and predictable.
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 approach results in an extremely low alkaloid content, with nicotine levels reduced to half or less of the control levels, without causing malformation or early senescence, thus overcoming the limitations of previous methods.
Implementation Method 1
AO is an enzyme that produces iminoaspartic acid by catalyzing oxidation of aspartic acid
Data Source
AI summary
An embodiment of the present invention provides a tobacco plant having a low alkaloid content. In the tobacco plant, a function of a gene encoding aspartate oxidase AO2 is suppressed.