Tomato BRIX Introgression Without Linked Leaf Necrosis
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Solution Overview
Problem
The introduction of BRIX-increasing alleles from wild tomato relatives into cultivated lines is hindered by the presence of linked deleterious alleles causing leaf necrosis, which makes it difficult to develop tomato varieties with improved fruit quality without unacceptable traits.
Innovation Solution
Development of novel molecular markers, such as M2 (SEQ ID NO:6) and M3 (SEQ ID NO:11), to uncouple the BRIX increasing locus from the necrosis locus on chromosome 1, allowing for the introgression of a reduced recombinant chromosomal segment that confers increased BRIX without leaf necrosis, and the use of marker-assisted selection (MAS) to identify and select plants with the desired trait.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If BRIX-increasing alleles from wild tomato relatives are introduced into cultivated lines, then fruit quality (BRIX levels) is improved, but leaf necrosis occurs due to linked deleterious alleles
Solution Approach 1:
The patent divides the chromosomal region into discrete segments defined by molecular markers. By identifying specific marker combinations (e.g., M2-M3-M4-M5 on chromosome 1), the breeder can select for the BRIX-increasing allele while excluding the necrosis-causing allele. This segmentation allows independent selection of beneficial and harmful genetic elements.
Solution Approach 2:
The patent extracts the BRIX-increasing allele from its original genetic background by using marker-assisted selection to isolate the specific chromosomal segment containing the desired allele while removing linked deleterious alleles. The marker system enables the extraction of only the beneficial genetic material (BRIX increase) without the harmful linked traits (necrosis).
2Manufacturing precision
If marker-assisted selection is used to identify plants with desired traits, then breeding precision is improved, but the complexity of the breeding program increases due to multiple marker loci analysis
Solution Approach 1:
The patent performs preliminary action by developing and validating the molecular marker system (M1-M13) before the actual breeding program. The markers are pre-characterized and their locations on chromosome 1 are predetermined. This preliminary preparation simplifies the subsequent breeding process, as breeders can directly use the established marker framework without needing to develop new markers during the breeding program.
Solution Approach 2:
The patent uses molecular markers as intermediaries between the visible phenotype (BRIX levels, necrosis) and the underlying genotype. Instead of directly measuring complex traits like fruit quality or disease resistance, the markers serve as convenient proxies that are easier to assay. This intermediary approach simplifies selection while maintaining precision.
Data Source
AI summary
Tomato plants exhibiting fruit with increased BRIX content are provided, together with methods of producing, identifying, or selecting plants or germplasm with an increased BRIX phenotype and lacking undesirable leaf necrosis. Such plants include tomato plants comprising introgressed genomic regions conferring increased BRIX without necrosis. Compositions, including novel polymorphic markers for detecting plants comprising introgressed alleles providing increased BRIX without necrosis, are further provided.