Exogenous Melatonin Treatment Increases Chilling Tolerance and Induces Defense Response in Harvested Peach Fruit during Cold Storage

Abstract

The effect of exogenous melatonin on chilling injury in peach fruit after harvest was investigated. To explore the optimum concentration of melatonin for chilling tolerance induction, peach fruit were treated with 50, 100, or 200 μM melatonin for 120 min and then stored for 28 days at 4 °C. The results showed that application of melatonin at 100 μM was most effective in reducing chilling injury of peach fruit after harvest. Peaches treated with melatonin at this concentration displayed higher levels of extractable juice rate and total soluble solids than the non-treated peaches. In addition, melatonin treatment enhanced expression of PpADC, PpODC, and PpGAD and consequently increased polyamines and γ-aminobutyric acid (GABA) contents. Meanwhile, the upregulated transcripts of PpADC and PpODC and inhibited PpPDH expression resulted in the higher proline content in melatonin-treated fruit compared to the control fruit. Our results revealed that melatonin treatment may be a useful technique to alleviate chilling injury in cold-stored peach fruit. The chilling tolerance of harvested peaches induced by melatonin treatment is associated with higher levels of polyamine, GABA, and proline. These data provided here are the first protective evidence of exogenous melatonin in harvested horticultural products in response to direct chilling stress.

Exogenous Melatonin Improves Plant Iron Deficiency Tolerance via Increased Accumulation of Polyamine-Mediated Nitric Oxide

“…Evidence gathered in recent years has indicated that melatonin improves the tolerance of plants to abiotic stress, which relates to the metabolic pathways of polyamine [12,41,42]. Lei et al [41] have reported that the melatonin-induced increase of polyamine, including Put and Spm, is responsible for mitigating cold-induced apoptosis in carrot suspension cells.…”

“…Lei et al [41] have reported that the melatonin-induced increase of polyamine, including Put and Spm, is responsible for mitigating cold-induced apoptosis in carrot suspension cells. Moreover, Cao et al [42] have reported that melatonin treatment markedly up-regulates the expression of polyamine biosynthesis-related genes, such as PpADC and PpODC , and results in a significant increase of polyamine levels in harvested peach fruit, which contributes to enhancing the tolerance of harvested peaches to chilling stress. Similar results were found in this study showing exogenous melatonin rapidly induced the polyamine biosynthesis in Arabidopsis plants under +Fe and −Fe conditions.…”

“…Melatonin can alleviate cold-induced apoptosis in carrot suspension cells by increasing the content of Put and Spd [41]. Additionally, melatonin treatments enhance the tolerance of harvested peach fruits to chilling stress, which is associated with the increased polyamine content [42]. These findings indicate that melatonin regulates plant abiotic stress responses, possibly involving polyamine-mediated NO accumulation.…”

Postharvest melatonin treatment reduces chilling injury in sapota fruit

“…Melatonin is a member of the acetamides and tryptamines and is considered as an endogenous signaling molecule, which has been investigated in plants to reduce biotic and abiotic stresses . Melatonin treatment has been shown to decrease CI in peach fruit, with commensurate increases in γ‐aminobutyric acid (GABA) and proline accumulation . However, the effect of postharvest melatonin treatment on CI in sapota fruit during cold storage has not been investigated.…”

“…7 Melatonin treatment has been shown to decrease CI in peach fruit, with commensurate increases in γ-aminobutyric acid (GABA) and proline accumulation. 8 However, the effect of postharvest melatonin treatment on CI in sapota fruit during cold storage has not been investigated. To investigate the effects of melatonin on chilling tolerance of sapota fruit during cold storage, a range of physiological and biochemical parameters were measured following postharvest melatonin treatment and fruit storage.…”