Chilling injury (CI) is a major limiting factor in the retention of the postharvest quality of chilling-sensitive vegetables and fruit stored at low temperatures. The enhanced chilling tolerance induced by methyl jasmonate (MeJA) treatment might be related to the polyamines biosynthesis. However, the molecular mechanism of polyamines biosynthesis induced by MeJA is far from clear. Here, we found that the application of 0.05 mmol L⁻¹ MeJA enhanced the activities of arginase, arginine decarboxylase and ornithine decarboxylase, as well as the transcripts of SlARG1, SlARG2, SlADC and SlODC, promoted the accumulations of polyamines and further inhibited CI development. In addition, polyamines induced by MeJA were strongly positively correlated with the SlMYC2 expression level. Moreover, MeJA-induced polyamines biosynthesis was largely inhibited due to the silencing of SlMYC2. The (SlMYC2-silenced + MeJA)-treated fruit possessed higher incidence and index of CI than the MeJA-treated fruit. Combining these findings with results of the principal component analysis, we concluded that SlMYC2 is involved in MeJA-induced chilling tolerance in postharvest tomato fruit by regulating polyamines biosynthesis. Furthermore, the electrophoretic mobility shift and dual-luciferase reporter assays indicated that SlMYC2 could activate the transcription of SlARG1, SlARG2, SlADC and SlODC by binding directly to G/E-box elements in their promoters. From the findings, it was revealed that the targeted up-regulation of SlARG1, SlARG2, SlADC and SlODC by SlMYC2 is involved in MeJA-induced polyamines biosynthesis, which enhances chilling tolerance in tomato fruit.

低温伤害（CI）是限制低温保存的对低温敏感的蔬菜和水果收获后品质保持的主要限制因素。茉莉酸甲酯（MeJA）处理诱导的耐寒性增强可能与多胺的生物合成有关。但是，由MeJA诱导的多胺生物合成的分子机制尚不清楚。在这里，我们发现0.05 mmol L ^-1 MeJA的应用增强了精氨酸酶，精氨酸脱羧酶和鸟氨酸脱羧酶的活性，以及SlARG1，SlARG2，SlADC和SlODC的转录本，促进了多胺的积累并进一步抑制了CI的发展。另外，由MeJA诱导的多胺与SlMYC2表达水平强烈正相关。而且，由于SlMYC2的沉默，MeJA诱导的多胺的生物合成被大大抑制。（SlMYC2沉默+ MeJA）处理的水果比MeJA处理的水果具有更高的CI发生率和CI指数。将这些发现与主成分分析结果相结合，我们得出结论，SlMYC2通过调节多胺的生物合成参与了MeJA诱导的番茄采后果实的耐冷性。此外，电泳迁移率的改变和双重荧光素酶报告基因的检测结果表明，SlMYC2可以激活SLEMYC2的转录。通过直接结合至其启动子中的G / E-box元件，SlaRG1，SlARG2，SlADC和SlODC。从发现中发现，SlMYC2对SlARG1，SlARG2，SlADC和SlODC的靶向上调与MeJA诱导的多胺生物合成有关，这增强了番茄果实的耐冷性。