Integrative analysis of postharvest chilling injury in cherry tomato fruit reveals contrapuntal spatio-temporal responses to ripening and cold stress

Abstract

Postharvest chilling injury (PCI) reduces fruit quality and shelf-life in tomato ( Solanum lycopersicum L.). PCI has been traditionally studied in the pericarp, however its development is likely heterogeneous in different fruit tissues. To gain insight into PCI’s spatio-temporal development, we used postharvest biomarkers e.g. respiration and ethylene rates, ion leakage etc., to confirm the occurrence of PCI, and compared these data with molecular (gene expression), biophysical (MRI data) and biochemical parameters (Malondialdehyde (MDA) and starch content) from the pericarp or columella. Tissues were stored at control (12.5 °C) or PCI-inducing temperatures (2.5 or 5 °C) followed by rewarming at 20 °C. MRI and ion leakage revealed that cold irreversibly impairs ripening-associated membrane liquefaction; MRI also showed that the internal and external fruit tissues responded differently to cold. MDA and especially starch contents, were affected by chilling in a tissue-specific manner. The expression of the six genes studied: ACO1 and ACS2 (ripening), CBF1 (cold response ), DHN , AOX1a and LoxB (stress-related) showed non-overlapping temporal and spatially-specific responses. Overall, the data highlighted the interconnectedness of fruit cold response and ripening, and showed how cold stress reconfigures the latter. They further underscored that multidimensional spatial and temporal biological studies are needed to develop effective solutions to PCI.

Transcriptional Analysis of C-Repeat Binding Factors in Fruit of Citrus Species with Differential Sensitivity to Chilling Injury during Postharvest Storage

“…These mutants also showed a modest reduction in CBF3 and CBF2 expression during cold exposure, suggesting the involvement of the three genes in Arabidopsis cold acclimation [ 51 ]. Similar to our results, CBF1 expression has been associated with chilling-resistant table grape cultivars induced by CO 2 -treatments that alleviated cold stress [ 40 , 41 ], revealing a diverse function of these genes depending on the fruit species, developmental stage, and severity of the cold stress [ 58 ]. In Hami melon fruit, an increase in CBF1 and CBF3 gene expression during cold storage was correlated with a lower CI index in the tolerant cultivar [ 38 ].…”

“…Different studies reported increased expression of CBFs in fruit, such as peach [ 28 , 55 ], mango [ 56 ], Hami melon [ 38 ], oil palm fruit [ 24 ], grape [ 40 , 41 ], and tomato [ 37 , 57 , 58 ] subjected to low temperature but also other stresses or ABA (abscisic acid) treatment, indicating a regulation by osmotic-related stress. Interestingly, in several instances, increases in their expression have been associated with a higher tolerance to chilling-related disorders [ 28 ].…”

“…In Hami melon fruit, an increase in CBF1 and CBF3 gene expression during cold storage was correlated with a lower CI index in the tolerant cultivar [ 38 ]. During tomato fruit storage at 2.5 °C, CBF1 expression peaked after 1–24 h of cold exposure and declined afterward [ 58 ]. In peach fruit, PpCBF genes induction was accompanied by a decrease in CI symptoms during postharvest cold storage [ 28 ].…”

Can gene editing reduce postharvest waste and loss of fruit, vegetables, and ornamentals?

“…The goal of postharvest management is therefore to control this progression to senescence, i.e., to pause the ripening process for shipping and storage, and then to restart it with a minimal loss of quality. However, the processes that control the ripening-to-senescence transition dictate quality, creating a dilemma, whereby altering ripening biology via refrigeration, chemicals, or other means to lengthen shelf-life, often unavoidably disrupts ripening outcomes and reduces quality 28 . This leads to consumer rejection and postharvest waste.…”

“…Further, the symptoms are often hard to specifically ascribe to chilling injury: PCI-accelerated decay is often diagnosed as postharvest disease or premature senescence 212 , and poor flavor induced by PCI is often blamed on variety-type or early-harvest. PCI is insidious because it is difficult to detect, and it is therefore not properly documented 28 . It also adds constraints to postharvest management strategies for sensitive crops, as preventing PCI requires faster shipping at higher temperatures or shorter storage times.…”