Abstract

Tomato (Solanum lycopersicum L.) is one of the most economically important horticultural crops globally. Consumers value its organoleptic traits but there is general dissatisfaction in terms of quality. One reason for this is inadequate postharvest handling. A common strategy to maintain shelf-life is to manage the storage temperature i.e. refrigeration; however, this leads to a loss of quality in tomato and other fruit from tropical and subtropical origin. Tomatoes are susceptible to postharvest chilling injury (PCI), which is a series of complex disorders that occur when fruit are exposed to temperatures between 0 and 12.5°C. Damage is initiated during the cold, but symptoms are manifested when the fruit is rewarmed. It is necessary to understand the spatial and temporal evolution of PCI events in order to develop a consistent source of tolerance to PCI. We are assessing the evolution of PCI in tomato fruit by monitoring the spatio-temporal expression of (i) key genes in the tomato fruit cold signal transduction pathway, (ii) biophysical changes in fruit non-destructively using Magnetic Resonance Imaging (MRI) and (iii) known indices for changes in membrane permeability, global metabolic status, level of oxidative stress and visual evaluations of the fruit. To this end, cherry tomato fruit cv. Sungold were stored at two chilling (2.5 and 5°C) and a control (12.5°C) temperature up to 21 days. After 7, 14 and 21 days, fruit were transferred to 20°C for 1 week to simulate commercial handling. Work is in progress, but preliminary data suggest that the disorder was progressive over time, enhanced after rewarming and presented tissue-differential manifestation.