Non-Transgenic SBEII Mutations for Wheat Resistant Starch
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Solution Overview
Problem
Current wheat cultivars lack commercially available lines with increased amylose and resistant starch levels, hindered by limited genetic diversity, polyploid nature, and close chromosomal location of SBEIIa and SBEIIb genes, making it difficult to achieve significant phenotypic changes through single gene alterations.
Innovation Solution
Introduction of non-transgenic mutations in one or more SBEII genes, specifically targeting SBEIIa and/or SBEIIb, to reduce enzyme activity and increase amylose and resistant starch levels, utilizing a method that involves mutagenesis and selective breeding to combine mutations across homoeologous genes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If single gene alterations are made in SBEIIa or SBEIIb, then amylose and resistant starch levels increase, but phenotypic changes are limited due to polyploid nature and gene redundancy
Solution Approach 1:
The patent combines mutations in multiple homoeologous SBEII genes (SBEIIa, SBEIIb, and their duplicates in different genomes) to achieve significant phenotypic changes. By merging effects from multiple gene copies, the invention overcomes the redundancy problem in hexaploid wheat and achieves substantial increases in amylose and resistant starch levels that cannot be obtained through single gene alteration alone.
Solution Approach 2:
The patent utilizes mutagenesis to create specific parameter changes in the SBEII genes, including point mutations, insertions, and deletions that alter enzyme activity. By changing the genetic parameters of multiple homoeologous genes simultaneously, the invention achieves the desired phenotypic changes in starch composition while maintaining viability and productivity.
2Quantity of substance
If mutations are introduced in SBEII genes to increase amylose content, then resistant starch levels increase, but genetic diversity is limited and commercial availability is restricted
Solution Approach 1:
The patent employs self-service mutagenesis techniques that allow the wheat plants to undergo spontaneous mutations in their SBEII genes through exposure to mutagens. This self-service approach, combined with selective breeding, enables the creation of commercially viable lines with increased resistant starch content without requiring complex external genetic modification systems.
Solution Approach 2:
The patent performs preliminary mutagenesis on wheat lines before they are released for commercial use. By pre-introducing and stabilizing the desired mutations in controlled breeding programs, the invention ensures that commercially available wheat varieties will have the desired increased amylose and resistant starch levels, overcoming the barrier of limited genetic diversity in existing cultivars.
3Quantity of substance
If SBEIIa and SBEIIb genes are altered to reduce enzyme activity, then amylose levels increase, but close chromosomal location makes independent alteration difficult
Solution Approach 1:
The patent segments the wheat genome into different homoeologous groups (A, B, and D genomes) and targets specific SBEII genes within each group independently. By treating the six copies of SBEII genes as separate target segments, the invention can apply mutagenesis and selective breeding to each segment independently, overcoming the physical proximity problem on chromosomes and enabling cumulative effects on amylose content.
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
Results in wheat plants and derived products with enhanced amylose and resistant starch content, providing healthier food options by managing blood sugar levels and promoting colon health without the use of genetic modification.
Implementation Method 1
a method that involves mutagenesis and selective breeding to combine mutations across homoeologous genes
Implementation Method 2
resistant starch is defined as starch that is not digested in the small intestine of healthy individuals but is fermented in the large intestine
Data Source
AI summary
A series of independent human-induced non-transgenic mutations found at one or more of the SBEII genes of wheat; wheat plants having these mutations in one or more of their SBEII genes; and a method of creating and finding similar and/or additional mutations of SBEII by screening pooled and/or individual wheat plants. The seeds and flour from the wheat plants of the present invention exhibit an increase in amylose and resistant starch without having the inclusion of foreign nucleic acids in their genomes. Additionally, the wheat plants of the present invention exhibit altered SBEII activity without having the inclusion of foreign nucleic acids in their genomes.