Functional contribution of PSY1 and SlFSR to fruit quality variation under organic cultivation

Tomatoes are among California’s most important agricultural commodities, underpinning the state’s economy and contributing to food security. Yet the industry faces growing pressure from food waste, climate change, and rising consumer demand for organic produce. Improving tomato fruit quality and extending shelf life are key strategies to reduce spoilage, boost marketability, and enhance sustainability across both conventional and organic systems. Recent identification of tomato-specific genes, including the fruit shelf-life regulator SlFSR, creates new opportunities to strengthen traits that matter directly to California growers and supply chains.

Tomatoes (Solanum lycopersicum) are valued for their culinary versatility and nutritional benefits, especially antioxidants like lycopene that drive both red color and health appeal. However, extending shelf life without sacrificing quality remains difficult. SlFSR has been shown to regulate shelf life by influencing cell wall–modification genes without disrupting ripening, while lycopene biosynthesis is controlled by Phytoene Synthase (PSY1). To examine how these genes behave in organic breeding, two organic lines (Royal Iris and Krimson Round) were crossed to produce reciprocal hybrids, and parents, F1, and F2 generations were grown in a certified organic field. Phenotypes were recorded and qRT-PCR was used to quantify SlFSR and PSY1 expression across generations. Preliminary results indicate that hybridization increases expression of both genes in F1 plants, consistent with improved shelf life and carotenoid accumulation, while the F2 generation shows wider variation reflecting inheritance and selection potential. Together, the findings suggest that traditional breeding paired with expression-based selection could offer a practical, sustainable path to reducing food waste and improving nutritional quality in California’s organic tomato production.