Soybean Genetic Transformation Using PMI Selectable Marker
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Solution Overview
Problem
The use of antibiotic and herbicide resistance genes as selectable markers in genetic transformation of soybeans poses environmental risks and is inefficient, with the 6-phosphomannose isomerase (PMI) gene being ineffective due to high endogenous expression in dicotyledon plants, limiting its application in soybean genetic transformation.
Innovation Solution
A soybean genetic transformation method using PMI as a selectable marker, involving soaking soybean explants in a recombinant Agrobacterium-containing infection suspension, co-culturing, and culturing on a selective medium with mannose to inhibit non-transformed cell growth, allowing transformed cells to grow normally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PMI gene is used as selectable marker in soybean transformation, then environmental safety is improved, but transformation efficiency deteriorates due to high endogenous expression
Solution Approach 1:
The patent extracts the PMI gene from the soybean genome by using a soybean-specific promoter (GmPMI promoter) that is inactive in transformed cells, thereby eliminating the interference of endogenous PMI expression while maintaining environmental safety benefits
Solution Approach 2:
The patent applies local quality by using tissue-specific or condition-specific promoters to drive PMI expression only in transformed cells under specific conditions, allowing differential expression between transformed and non-transformed cells despite high background expression in soybean
2Productivity
If antibiotic or herbicide resistance genes are used as selectable markers, then transformation selection is improved, but environmental safety deteriorates due to toxicity and horizontal gene transfer
Solution Approach 1:
The patent converts the normally harmful or neutral mannose substance into a beneficial selective agent by coupling it with PMI gene expression, where mannose becomes toxic only to non-transformed cells that lack the transgenic PMI enzyme, thereby eliminating the need for toxic antibiotics or herbicides
Solution Approach 2:
The patent introduces PMI gene as an intermediary that enables cells to metabolize mannose, creating a bridge between the safe substance (mannose) and effective selection, where the PMI enzyme acts as the mediator that confers resistance to mannose toxicity
3Object-affected harmful factors
If traditional selectable markers are replaced with PMI gene, then environmental impact is reduced, but additional transformation experiments are required increasing labor and cost
Solution Approach 1:
The patent merges the selection marker function with the endogenous metabolic pathway by using the soybean-specific PMI promoter to drive PMI expression, combining the selectable marker function with native soybean gene regulation to eliminate the need for separate verification experiments
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 method achieves a transformation frequency of 1.9% to 6.3% for different soybean cultivars, overcoming the limitations of traditional PMI gene use and providing a safe and efficient genetic transformation process.
Implementation Method 1
mannose cannot be absorbed and utilized directly by plants until it is isomerized to fructose 6-phosphate by 6-phosphomarmose isomerase
Implementation Method 2
soaking soybean explants in a recombinant Agrobacterium-containing infection suspension to obtain infected explants
Implementation Method 3
regulation of a ratio of mannose to sucrose in a culture medium can starve non-transformed plant cells, making transformed cells grow normally
Data Source
AI summary
The present invention provides a soybean genetic transformation method using PMI as selectable gene, and relates to the technical field of genetic engineering. In the soybean genetic transformation method of the present invention, using the PMI gene as a selectable marker, soybean explants are infected by recombinant Agrobacterium with the PMI gene and a target gene, followed by co-culture; without recovery culture, the co-cultured explants are directly selected by a selective medium supplemented with mannose, where transformed explants with the PMI gene grow normally under selection pressure of mannose, while non-transformed explant growth is inhibited, thereby selecting successfully transformed positive plants; after shoot elongation and transplantation of the positive plants obtained, genetically transformed soybean plants are obtained successfully. Using the soybean genetic transformation method as provided by the present invention, soybeans can be genetically transformed by PMI genes derived from any species, achieving safe soybean genetic transformation.