LOW OXYGEN AND OZONE POSTHARVEST STORAGE OF ABATE FETEL PEAR FRUİT: A STUDY OF THE EFFECTS ON SOFT SCALD THROUGH A MOLECULAR APPROACH

Abate fetel (pyrus communis) is a pear variety easily recognizable and highly prized which gained popularity among Italian farmers and consumers due to its distinctive flavor, texture and culinary versatility. In fact, Italy is the largest European producer of the variety and the protected geographical indication (PGI) status of the European Union have been attributed to Abate fetel pears preserving its authenticity, reputation and quality standards. Abate fetel cultivar is very susceptible to the physiological disorder ‘soft scald ‘that appears as a band of dark tissue on the peel of the fruit with occasional browning into the flesh particularly during controlled atmosphere postharvest storage hence making such common technology commercially not really suitable. The etiology behind soft scald incidence is still not well understood and up to date little is known about the molecular mechanisms underlying the disorder. Aiming at finding the better strategy to prevent the disorder occurence and to ensure long term storage of Abate fetel cultivar, Pears from two different orchards (696, 263) stored under six distinct conditions each with three oxygen levels (21%, air-NA; 2%, controlled atmosphere-CA; 0,3%, controlled atmosphere-CA) at 0.5 degree were evaluated after 5 months. Additionally, each condition for both orchards was combined with continuous exposure to 0.03 ppm of Ozone (O3) in order to investigate the influence of ozone and to examine if oxygen stress may interfere with ozone response after postharvest life. Measurements of the physiological parameters such as ethylene and firmness were firstly evaluated. Ethylene biosynthesis related gene ‘ACO’, ethylene signaling gene ‘ERS1’, polygalacturonase gene ‘PG’, genes involved in sugar metabolism ‘APRT and PGM’ and manganese superoxidase dismutase gene ‘MnSOD’ all showed a unique transcriptional regulation in both control and low-oxygen samples. Based on these molecular markers, The respiration activity and ripening process appear to be affected by the hypoxic conditions and MnSOD gene regulation particulary seems to be more involved in the development of soft scald. The addition of ozone did not have a big impact on the pear quality and scald incidence. Further studies are needed to gather more information on the identification of differentially expresssed genes while comparing different samples through RNA sequencing.