Investigation of the sensitivity of different tomato types to postharvest low oxygen stress

This study was conducted between 2020 and 2024. In the first year, the ripening physiology of tomato fruits was examined by applying 1-methylcyclopropene and low oxygen storage treatments. In the second year, genes related to ripening were investigated using low oxygen. In the framework of the research, a total of 14 different genotypes were used, including the most cultivated tomato varieties of different tomato types commercially grown in Turkiye, as well as the 'ripening inhibitor' mutant and its wild type. The fruit samples used during the study were grown in a greenhouse at Akdeniz University and were harvested at the mature green stage to be used in the experiments. In the first year, a 500 ppb 1-MCP application was performed. For the storage of tomatoes under controlled atmosphere conditions, three different low oxygen levels were used: 1%, 3%, and 5%. The control group fruits were stored under normal atmospheric conditions. The fruits were stored for 20 days and sampled at 5-day intervals. In the first year, to understand the effects of 1-MCP and low oxygen levels on ripening physiology, weight loss, skin color (L*, C*, h°), soluble solids content, titratable acidity, fruit firmness, total chlorophyll, lycopene, malic acid, citric acid, fumaric acid, succinic acid, glucose, sucrose, fructose, total phenol, ascorbic acid, ethylene production, total antioxidant activity, respiration rate, and the expression levels of cell wall modification genes (PG2, PME1, PL, EXP1) were analyzed. Based on the findings obtained, four varieties with contrasting characteristics were selected for the transcriptome profiling study in the second year. Overall, hue angle, chroma, titratable acidity, soluble solids content, total antioxidant activity, total phenol, total chlorophyll, lycopene, ascorbic acid, fructose, sucrose, succinic acid, ethylene production, and respiration rate were found to be related to ripening regardless of the treatments. Additionally, it was proven that the 5% O2 level is an alternative to 1-MCP. This thesis uncovered that some varieties ripened faster than others under controlled atmosphere conditions, and a relationship was found between respiration rate and oxygen utilization and ripening. Finally, as a result of the transcriptome profiling study conducted using low oxygen, 165 candidate genes potentially related to ripening were identified.