Evaluation of Genetic Response and the Impact of Tomato yellow leaf curl virus (TYLCV) Infection on Chemical and Floral Traits in Tomato Cultivars (Solanum lycopersicum)

Tomato (Solanum lycopersicum), belonging to the Solanaceae family, is one of the most economically important crops worldwide due to its high nutritional and medicinal value. This study aimed to evaluate the response of ten tomato cultivars (MAHAVIS F1, BAHJA F1, OSCAR F1, Mercur, Balkis F1, T77, Zaha F1, TALA F1, Nermin 66, FAIRUZ F1) to Tomato yellow leaf curl virus (TYLCV) infection and to investigate its effects on selected biochemical and floral parameters. The experiments were conducted in plastic greenhouses at the Department of Plant Protection, College of Agriculture, University of Karbala, during the 2024–2025 growing season. The results revealed significant variation in infection severity among the cultivars. The FAIRUZ F1 cultivar recorded the highest infection severity (86.67%), while MAHAVIS F1 and BAHJA F1 exhibited the highest tolerance, with the lowest infection severities of 6.67% and 13.33%, respectively. Virus infection led to a significant reduction in magnesium content (0.87 mmol/L) and nitrogen content (2.29%) in infected plants compared to uninfected ones. Conversely, a significant increase in sodium (25.18 ppm) and potassium (124.04 ppm) concentrations was observed in infected plants. Additionally, the infection caused a significant decrease in floral growth indicators, with an average of 15.20 inflorescences per plant and 4.19 flowers per inflorescence in infected plants compared to uninfected ones The study concludes that TYLCV infection has a significant negative impact on the nutritional characteristics and flower development of tomato plants, with promising genetic differences in tolerance. Therefore, it is recommended to use highly tolerant cultivars such as MAHAVIS F1 and BAHJA F1 as valuable genetic resources in future breeding programs aimed at producing commercial varieties resistant to the virus.