Delayed response to cold stress is characterized by successive metabolic shifts culminating in apple fruit peel necrosis

Abstract

BackgroundSuperficial scald is a physiological disorder of apple fruit characterized by sunken, necrotic lesions appearing after prolonged cold storage, although initial injury occurs much earlier in the storage period.To determine the degree to which the transition to cell death is an active process and specific metabolism involved, untargeted metabolic and transcriptomic profiling was used to follow metabolism of peel tissue over 180 d of cold storage.ResultsThe metabolome and transcriptome of peel destined to develop scald began to diverge from peel where scald was controlled using antioxidant (diphenylamine; DPA) or rendered insensitive to ethylene using 1-methylcyclopropene (1-MCP) beginning between 30 and 60 days of storage. Overall metabolic and transcriptomic shifts, representing multiple pathways and processes, occurred alongside α-farnesene oxidation and, later, methanol production alongside symptom development.ConclusionsResults indicate this form of peel necrosis is a product of an active metabolic transition involving multiple pathways triggered by chilling temperatures at cold storage inception rather than physical injury. Among multiple other pathways, enhanced methanol and methyl ester levels alongside upregulated pectin methylesterases are unique to peel that is developing scald symptoms similar to injury resulting from mechanical stress and herbivory in other plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-017-1030-6) contains supplementary material, which is available to authorized users.

Apple fruit superficial scald resistance mediated by ethylene inhibition is associated with diverse metabolic processes

“…The first subgroup is involved in controlling regulatory processes related to cold tolerance, while the second is more associated with inducing cold acclimation. The idea that more energy is needed to activate new physiological activities in these samples is supported by the observed increased expression of chlorophyll‐A‐B‐binding and OEE genes (Tadiello et al ., ; Gapper et al ., ). Moreover, it has been reported that rice ( Oryza sativa ) and maize ( Zea mays ) lines that are more tolerant of low temperature have higher levels of chlorophyll (Sanghera et al ., ).…”

“…This observation is consistent with the work of Gapper et al . () who reported pectin methylesterase activity during scald symptom development compared with 1‐MCP‐treated fruit. In general, another mechanism that is employed in the fruit to repair damages induced by cold stress is the activation of FAD expression.…”

Comparative metabolites profiling of harvested papaya (Carica papaya L.) peel in response to chilling stress

“…The fruit peel metabolism was reported to be involved with the disorders caused by cold stress. Metabolic shifts of fruit peel is related to peel necrosis of apple fruit under cold stress . For tropical fruit, CI disorder was also related to metabolic changes in mango, dragonfruit, banana, and so on.…”

“…Metabolic shifts of fruit peel is related to peel necrosis of apple fruit under cold stress. 13 For tropical fruit, CI disorder was also related to metabolic changes in mango, 5,8 dragonfruit, 14 banana, 15 and so on. Apart from visible symptoms, chilling may also induce changes in fruit textural properties and flavor.…”

Pre-harvest climate and post-harvest acclimation to cold prevent from superficial scald development in Granny Smith apples

“…Although superficial scald was intensively studied for several years, its molecular or biochemical determinism was mainly analysed after long time cold storage during symptom development 3,9 , or under 1-MCP or DPA treatments 4,7,8,[10][11][12] . Thus, early determinisms linked to the pre-harvest conditions, in particular to climate or fruit maturity stages remain poorly understood.…”