Tomato Plant Resistance via Cis-Coupled OL4 and TY1 Genes
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Solution Overview
Problem
Current methods for breeding tomato plants resistant to Tomato Yellow Leaf Curl Virus (TYLCV), powdery mildew, and nematodes face challenges due to the genetic linkage of resistance genes, leading to recombination suppression and the rapid evolution of pathogens that bypass existing resistance, necessitating the introduction of new gene combinations.
Innovation Solution
The combination of the OL4 gene for resistance to powdery mildew and nematodes and the TY1 gene for TYLCV resistance on the same chromosome without including the Mi-1 gene, utilizing specific markers like SSR-OL4, TO-0178067, and Mi2.3 for detection, to create a tomato plant that is resistant to all three without the Mi-1 gene in cis linkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TY1 gene is introgressed into cultivated tomatoes to confer resistance to TYLCV, then resistance to TYLCV is improved, but undesired agronomical traits and genetic linkage to Mi-1 gene are introduced
Solution Approach 1:
The invention extracts and combines specific resistance genes (TY1 for TYLCV and OL4 for powdery mildew and nematodes) while deliberately excluding the Mi-1 gene and its associated undesired traits. This selective extraction of beneficial genes without harmful linkages resolves the contradiction by obtaining TYLCV resistance without the negative agronomical effects.
Solution Approach 2:
The invention segments the resistance gene cluster by separating TY1 and OL4 genes from the Mi-1 gene through recombination. This segmentation allows independent inheritance of beneficial resistance traits while eliminating linkage to harmful traits, resolving the contradiction between disease resistance and undesired agronomical characteristics.
2Adaptability or versatility
If resistance genes are combined on the same chromosome to provide multiple disease resistances, then resistance coverage is improved, but recombination suppression occurs
Solution Approach 1:
The invention merges TY1 and OL4 resistance genes onto the same chromosome in coupling phase to provide combined resistance to TYLCV, powdery mildew, and nematodes. This merging improves resistance coverage while the specific chromosomal arrangement maintains recombination potential, resolving the contradiction between versatility and stability.
3Reliability
If existing resistance genes are used to protect tomato plants, then disease resistance is improved, but pathogens rapidly evolve to bypass existing resistance
Solution Approach 1:
The invention creates a composite resistance system by combining multiple resistance genes (TY1 and OL4) with different specificities against different pathogens. This composite approach provides broader and more durable resistance because pathogens would need to simultaneously overcome multiple resistance mechanisms, making it harder for them to evolve bypass strategies.
Data Source
AI summary
The present invention relates to Solanum lycopersicum (S. lycopersicum) plants with resistance to Tomato Yellow Leaf Curl Virus (TYLCV), powdery mildew (PM) and nematodes. According to the invention, the resistances are provided by coupling in cis on the same chromosome the OL4 gene conferring resistance to PM and nematodes and TY1 gene conferring resistance to TYLCV, without coupling the Mi-1 gene conferring resistance to nematodes in cis with said OL4 gene conferring resistance to PM and nematodes and TY1 gene conferring resistance to TYLCV. The genes can be present homozygously or heterozygously in the genome of the S. lycopersicum plants, and they confer resistance to TYLCV, PM and nematodes. The present invention also provides methods for making such plants, and to methods of detecting and/or selecting such plants.