Mutant Acetolactate Synthase G95A Selection Marker
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Solution Overview
Problem
Current methods lack a specific mutant ALS gene conferring high resistance to pyrimidinyl carboxy (PC) herbicides, which is essential for efficient selection and transformation of plants resistant to these herbicides.
Innovation Solution
A transformation method involving a recombination vector with a gene coding for a mutant acetolactate synthase protein, specifically with a glycine to alanine mutation at position 95, is used as a selection marker to cultivate plants resistant to PC herbicides by culturing transformed cells in the presence of pyrimidinyl carboxy herbicides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wild-type ALS gene is used as a selection marker, then transformed cells can be selected using herbicides, but the selection is not specific to PC herbicides and lacks high resistance
Solution Approach 1:
The invention applies local quality by introducing a specific point mutation (Glycine to Alanine at position 95) in the ALS protein sequence. This localized amino acid substitution at a specific position confers high resistance specifically to PC herbicides while maintaining sensitivity to other herbicide types, thereby achieving selective adaptation rather than broad-spectrum resistance.
2Adaptability or versatility
If multiple herbicide resistance genes are introduced to achieve broad resistance, then plants can resist multiple herbicide types, but the transformation complexity and selection difficulty increase
Solution Approach 1:
The mutant ALS gene serves multiple functions: it acts as both a selectable marker for transformed cells and confers herbicide resistance to the plant. By using a single gene that provides both selection capability and resistance function, the invention avoids the complexity of introducing multiple separate resistance genes while still achieving practical herbicide resistance.
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 method enables efficient selection and transformation of plants with high resistance specifically to PC herbicides, demonstrated by the G95A mutant ALS protein showing significant resistance to bispyribac-sodium and other PC herbicides, while maintaining low resistance to sulfonylurea and imidazolinone herbicides.
Implementation Method 1
Acetolactate synthase (hereinafter referred to as 'ALS') is a rate-limiting enzyme in the biosynthetic pathway of branched chain amino acids
Implementation Method 2
Plants with one or two nucleotide substitutions in a gene coding for ALS, which induce one or two amino acid substitutions in a region conserved among different species, are known as plants having resistance to these herbicides
Data Source
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AI summary
Transformed cells are efficiently selected using a mutant ALS gene having high specificity to PC herbicides. The transformation method comprises the steps of: transforming a host cell with a recombination vector containing a gene of interest and a gene coding for a mutant acetolactate synthase having mutation of glycine corresponds to position 95 of the amino acid sequence of a wild-type acetolactate synthase derived from rice to alanine; culturing the transformed cell obtained in the former step in the presence of a pyrimidinyl carboxy herbicide; and wherein the gene coding for the mutant acetolactate synthase is used as a selection marker.