Tomato Plants Disease Resistance Introgression
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Solution Overview
Problem
Current methods in plant breeding face challenges in introducing disease resistance alleles into tomato plants without linked deleterious traits, particularly for tomato chlorosis virus (ToCV) and Fusarium oxysporum f. sp. lycopersici (Fol) race 2, due to lack of specific markers and genetic linkage issues.
Innovation Solution
A recombinant chromosomal segment on chromosome 11 of Solanum lycopersicum is introduced, containing a ToCV resistance allele from Solanum chilense and a Fol race 2 resistance allele from Solanum pimpinellifolium, which are linked to avoid cold sensitivity and enhance resistance, using marker-assisted selection to identify and introgress these alleles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If disease resistance alleles are introduced into tomato plants, then resistance to diseases is improved, but cold sensitivity and reduced yield occur due to linked deleterious alleles
Solution Approach 1:
The patent segments the chromosomal region containing the disease resistance allele from the linked deleterious allele through recombination. Specifically, it isolates a 1.4 Mb chromosomal segment from Solanum pimpinellifolium that contains the Fol resistance allele (I-2) while excluding the linked cold sensitivity allele, achieving genetic separation of beneficial and harmful traits
Solution Approach 2:
The patent extracts only the beneficial disease resistance allele from the donor genome while leaving behind the deleterious linked allele. The 1.4 Mb introgressed segment is precisely delimited by molecular markers (SNP markers S1 and S2) to contain only the Fol resistance gene without the cold sensitivity trait, effectively taking out the harmful genetic element
2Reliability
If disease resistance alleles are introduced into tomato plants, then resistance to diseases is improved, but fruit size and quality are reduced due to linked deleterious alleles
Solution Approach 1:
The patent segments the chromosomal region to separate the disease resistance allele from linked deleterious alleles affecting fruit quality. The precisely defined 1.4 Mb introgressed segment contains only the beneficial Fol resistance gene while excluding other genes that could negatively impact fruit size and quality traits
Solution Approach 2:
The patent applies local quality by making the introgressed chromosomal segment highly specific and localized. The 1.4 Mb region is flanked by specific SNP markers (S1 at position 54,895,724 and S2 at position 55,443,272 on chromosome 11) to ensure that only the necessary resistance allele is introduced while maintaining the rest of the genome's native quality characteristics
3Measurement precision
If marker-assisted selection is used to identify disease resistance alleles, then selection accuracy is improved, but lack of specific markers limits its effectiveness
Solution Approach 1:
The patent performs preliminary action by developing and validating specific molecular markers (SNP markers S1 and S2) before breeding operations. These markers are预先 characterized to flank the Fol resistance allele, enabling accurate marker-assisted selection to be implemented in subsequent breeding programs without needing to discover markers during the breeding process
Data Source
AI summary
Tomato plants exhibiting resistance to tomato chlorosis virus and Fusarium oxysporum f. sp. lycopersici race 2 are provided, together with methods of producing, identifying, or selecting plants or germplasm with a tomato chlorosis virus and Fusarium oxysporum f. sp. lycopersici race 2 resistance phenotype and lacking an undesirable cold sensitivity trait. Such plants include tomato plants comprising recombinant genomic regions conferring disease resistance. Compositions, including novel polymorphic markers for detecting plants comprising introgressed disease resistance alleles, are further provided.