Maize Ht1 NLB18 Gene Editing for Northern Leaf Blight Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional breeding methods for introgressing northern leaf blight resistance into maize lines are inefficient and often result in yield penalties due to linkage drag, making it difficult to produce resistant plants effectively.
Innovation Solution
The method involves editing genes such as Ht1 and NLB18 in maize plants using CRISPR-Cas9 technology to introduce specific nucleotide sequences that confer enhanced resistance, allowing for the introduction of a single genomic locus with multiple resistance-conferring sequences, thereby reducing linkage drag and improving resistance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional breeding methods are used to introgress resistance genes into maize lines, then northern leaf blight resistance is improved, but yield is reduced due to linkage drag
Solution Approach 1:
The patent extracts only the essential resistance-conferring nucleotide sequences from the donor parent's genome and introduces them into the elite maize line using gene editing technology. This extraction approach separates the beneficial resistance traits from the linked detrimental genes that cause yield penalties, allowing resistance to be achieved without linkage drag.
Solution Approach 2:
The patent changes the genetic parameters of the maize plant by precisely editing specific nucleotide sequences in resistance genes (Ht1, Ht2, Ht3, Htm1, Htn1, HtN, HtP, ht4, or rt) or introducing sequences from resistant parents. This parameter change at the molecular level achieves resistance without the need for extensive backcrossing that typically introduces linkage drag.
2Reliability
If multiple resistance loci are introgressed via conventional means, then northern leaf blight resistance is enhanced, but the complexity and time required for breeding increases
Solution Approach 1:
The patent merges multiple resistance-conferring nucleotide sequences into a single edited genome by introducing them simultaneously through gene editing. This combining approach achieves the cumulative resistance effect of multiple loci without requiring separate breeding cycles for each locus, thereby reducing breeding complexity and time.
Solution Approach 2:
The patent replaces the mechanical breeding process (crossing, backcrossing, selection, and recombination over multiple generations) with a molecular-level gene editing system. This substitution allows precise introduction of resistance sequences directly into the target genome, eliminating the complex and time-consuming conventional breeding machinery.
3Reliability
If conventional breeding is used to introgress resistance genes, then resistance is achieved, but the time required for breeding is extended
Solution Approach 1:
The patent performs preliminary identification and selection of specific resistance-conferring nucleotide sequences from resistant parents before introducing them into the elite line. This preliminary preparation allows direct editing of the target sequences without requiring extensive generations of crossing and selection, significantly reducing the time needed to achieve resistance.
Solution Approach 2:
The patent replaces the time-consuming mechanical breeding process (multiple generations of crossing, backcrossing, and selection) with rapid gene editing technology. This substitution enables the introduction of resistance traits in a single generation or few generations, dramatically reducing the breeding time while maintaining resistance effectiveness.
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 the efficient production of maize plants with enhanced resistance to northern leaf blight by directly modifying key genes, reducing the need for multiple resistance loci introgression and minimizing yield penalties, resulting in more durable and broad-spectrum resistance.
Implementation Method 1
introducing a double-strand break or site-specific modification at one or more target sites in an endogenous HT1 encoding sequence in a maize plant cell
Data Source
AI summary
Compositions and methods for obtaining plant cells with modified Ht1 nucleotide sequences, modified NLB18 sequences, or both, are provided herein. The methods involve introducing double-strand breaks into the maize genome in an endogenous Ht1 encoding sequence, an endogenous NLB18 encoding sequence, or both, to modify the genomic sequence in order to enhance northern leaf blight resistance of a plant produced from the plant cell. Further provided are methods that introduce resistant alleles of Ht1 and/or NLB18 into specific sites in the genome. Plants produced by the plant cells, and seeds produced from the plants are also included. Guide polynucleotides are also provided for the use of the CRISPR-Cas system in inducing double strand breaks.