Cucumber FORC Resistance Introgression Without Fruit Shape Defects
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Solution Overview
Problem
Existing methods for introgressing Fusarium oxysporum f.sp. radicis cucumerinum (FORC) resistance alleles into cucumber plants are hindered by the association of these alleles with undesirable traits such as necrosis and poor fruit shape, and there is a lack of accurate markers for tracking these alleles during breeding.
Innovation Solution
The introduction of recombinant chromosomal segments flanked by specific SNP markers (e.g., SNP_Marker6 and SNP_Marker7 on chromosome 6, SNP_Marker1 and SNP_Marker2 on chromosome 3) that confer resistance to FORC without deleterious effects, accompanied by novel markers for accurate marker-assisted selection (MAS) to track and introgress these alleles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FORC resistance alleles are introgressed into cucumber plants, then resistance to FORC is improved, but fruit quality and plant architecture deteriorate due to linkage drag
Solution Approach 1:
The patent divides the chromosomal region containing the FORC resistance allele into smaller segments through recombination events. By creating recombinant chromosomal segments with defined boundaries flanked by specific SNP markers, the resistance allele is separated from adjacent deleterious alleles, allowing selective introgression of only the beneficial resistance trait without the harmful linked traits.
Solution Approach 2:
The patent extracts the FORC resistance allele from its original genetic background by utilizing recombination to separate it from deleterious alleles. The resistance allele is isolated within a specific recombinant chromosomal segment that can be precisely tracked and selected using flanking SNP markers, effectively removing the harmful linked traits while retaining the resistance benefit.
2Reliability
If conventional breeding methods are used to introgress FORC resistance alleles, then resistance is achieved, but the process is inefficient due to lack of accurate markers
Solution Approach 1:
The patent performs preliminary identification and characterization of SNP markers that flank the FORC resistance allele before the actual breeding process. These pre-validated markers enable breeders to directly track and select recombinant chromosomal segments containing the resistance allele, eliminating the need for time-consuming phenotypic screening and multiple generations of breeding to achieve the desired trait.
Solution Approach 2:
The patent replaces conventional mechanical phenotypic selection methods with molecular marker-assisted selection. Instead of relying on time-consuming visual assessment of resistance traits and multiple generations of breeding, the invention uses DNA-based SNP markers to directly identify and select plants containing the desired recombinant chromosomal segments, dramatically accelerating the breeding process.
3Productivity
If marker-assisted selection is used without accurate markers, then breeding efficiency is improved, but selection accuracy deteriorates
Solution Approach 1:
The patent introduces SNP markers as intermediary elements that mediate between the FORC resistance allele and the breeding selection process. These flanking SNP markers serve as reliable proxies that can be easily detected and used to track the inheritance of the resistance allele and define the boundaries of recombinant chromosomal segments, enabling accurate selection without directly assessing the resistance phenotype.
Data Source
AI summary
Cucumber plants exhibiting resistance to Fusarium oxysporum f.sp. radicis cucumerinum (FORC) are provided, together with methods of producing, identifying, or selecting plants or germplasm with a FORC resistance phenotype. Such plants include cucumber plants comprising introgressed genomic regions conferring disease resistance. Compositions, including novel polymorphic markers for detecting plants comprising introgressed disease resistance alleles, are further provided.