Guide RNA Cas9 System for Precise Plant Genome Editing
Solution Overview
Problem
Current methods for altering plant genomes, such as Agrobacterium infection and biolistic particle bombardment, result in random and unpredictable integration of transgenes, making it difficult to achieve specific modifications in defined regions, particularly for producing fertile plants with improved agronomic traits.
Innovation Solution
Employing a guide RNA/Cas endonuclease system to introduce targeted double-strand breaks in plant genomes, allowing for precise modification of specific sequences and traits, including the use of heterologous regulatory elements to enhance expression of genes related to traits like drought tolerance and yield improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Agrobacterium infection or biolistic particle bombardment is used to insert foreign DNA sequences, then transgenes can be integrated into the plant genome, but the integration occurs in a random and unpredictable copy number, making it difficult to achieve specific modifications in defined regions
Solution Approach 1:
The patent employs a guide RNA as an intermediary molecule that directs the Cas9 endonuclease to the specific target site in the plant genome. This RNA-mediated targeting system enables precise localization of the editing tool without requiring complex physical delivery mechanisms, thereby achieving site-specific modification with simplified methodology
Solution Approach 2:
The patent replaces mechanical transformation methods (Agrobacterium infection, biolistic bombardment) with a molecular recognition system based on guide RNA-Cas9 complex formation. This substitution transitions from physical delivery mechanisms to a sequence-specific molecular targeting approach, enabling precise genome editing without random integration
2Reliability
If traditional transformation methods are used to produce fertile plants with altered genomes, then genetic modification can be achieved, but the random integration pattern makes it difficult to control the location and copy number of transgenes
Solution Approach 1:
The guide RNA serves as a molecular intermediary that bridges the Cas9 endonuclease and the target DNA sequence. Through base-pairing interactions, the guide RNA ensures accurate positioning of the Cas9 complex at the intended genomic locus, thereby achieving reliable and precise genome modification
Solution Approach 2:
The patent utilizes changes in the guide RNA sequence (specifically the 20-nucleotide spacer region) to alter the target specificity of the Cas9 system. By modifying this parameter, the system can be directed to different genomic locations with high precision, enabling controlled and reliable genome editing at user-defined sites
3Productivity
If random transgene integration is used to alter plant phenotype, then foreign DNA can be inserted into the genome, but the unpredictable copy number and location make it difficult to achieve consistent agronomic trait improvement
Solution Approach 1:
The guide RNA acts as a directional intermediary that steers the Cas9 endonuclease to predetermined target sites associated with specific agronomic traits. This RNA-mediated guidance system enables efficient and precise placement of genetic modifications at loci known to influence desired phenotypes, thereby accelerating trait improvement programs
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 enables efficient and precise genome editing in plants, resulting in improved agronomic traits like increased yield, drought tolerance, and nitrogen use efficiency, while maintaining the native expression patterns of endogenous genes.
Implementation Method 1
a guide RNA that targets a polynucleotide involved in improving one or more agronomic characteristics of the plant
Implementation Method 2
a Cas endonuclease that creates a double strand break at the polynucleotide
Data Source
AI summary
Compositions and methods are provided for agronomic trait modification of a target sequence in the genome of a plant or plant cell. The methods and compositions employ a guide RNA/Cas endonuclease system to provide an effective system for modifying or altering target sites within a genomic region of a plant, plant cell or seed to provide improvement in a desirable agronomic trait such as drought, yield, and stress tolerance. Breeding methods for selecting plants utilizing a two component RNA guide and Cas endonuclease system are also disclosed. Compositions and methods are also provided for editing a nucleotide sequence in the genome of a cell.