Peach (Prunus persica Batsch ‘Yuhualu’) fruit are sensitive to chilling injury (CI). Proline, polyamine (PA), and nitric oxide (NO) are important small regulators of various metabolic pathways under chilling stress that mitigate CI. Ethylene is known to promote senescence and CI, while 1-methylcyclopropene (1-MCP) is an antagonist that inhibits the effects of ethylene. However, how 1-MCP and ethylene affect proline, PA, and NO levels under chilling stress remains unclear. To address these questions, 1-MCP (1 µL · L⁻¹) and ethylene (1 µL · L⁻¹) treatments were applied to peach fruit. Fruit were stored at 4 °C for 28 d, then moved to 25 °C for 3 d immediately after cold storage. Peach fruit exhibited CI symptoms after 7 d of cold storage with enhanced electrolyte leakage and malondialdehyde contents. The 1-MCP treatment significantly (P < 0.05) restrained peach CI, and fruit did not exhibit CI symptoms until 14 d of cold storage. Proline and PAs in peach under chilling stress were mostly synthesized from glutamate and arginine, which were catalyzed by Δ1-pyrroline-5-carboxylate synthetase and arginine decarboxylase, respectively. 1-MCP-treated fruit exhibited higher proline and PA contents and enhanced chilling tolerance compared to the control, while ethylene-treated fruit had lower proline and PA contents and reduced chilling tolerance. Ethylene-treated fruit, which exhibited more severe CI symptoms compared to the control, had significantly (P < 0.05) lower NO contents and NO synthase activities. However, NO may not be a direct acting factor in 1-MCP-induced chilling tolerance, as 1-MCP-treated fruit had lower NO contents and NO synthase activities compared to the control. In conclusion, proline and PA clearly played direct and important roles in 1-MCP-induced peach chilling tolerance, while NO may not be actively involved.

桃（Prunus persica Batsch'Yuhualu'）果实对冷害（CI）敏感。脯氨酸，多胺（PA）和一氧化氮（NO）是在缓解CI的低温胁迫下各种代谢途径的重要小调节剂。已知乙烯会促进衰老和CI，而1-甲基环丙烯（1-MCP）是抑制乙烯作用的拮抗剂。但是，1-MCP和乙烯如何在寒冷胁迫下影响脯氨酸，PA和NO含量仍不清楚。为了解决这些问题，请使用1-MCP（1 µL·L ^-1）和乙烯（1 µL·L ^-1））对桃果实进行了处理。将水果在4°C下保存28 d，然后在冷藏后立即移至25°C 3 d。冷藏7 d后，桃果实表现出CI症状，电解质渗漏和丙二醛含量增加。1-MCP治疗显着（P <0.05）抑制了桃的CI，并且果实在冷藏14 d之前没有表现出CI症状。低温胁迫下桃中脯氨酸和PAs主要由谷氨酸和精氨酸合成，分别由Δ1-吡咯啉-5-羧酸合成酶和精氨酸脱羧酶催化。1-MCP处理的水果与对照相比显示出较高的脯氨酸和PA含量，并增强了耐寒性，而乙烯处理的水果具有较低的脯氨酸和PA含量并降低了耐寒性。与对照组相比，乙烯处理的水果表现出更严重的CI症状，具有显着的（P <0.05）降低NO含量和NO合酶活性。但是，NO可能不是1-MCP诱导的耐寒性的直接作用因素，因为与对照组相比，经1-MCP处理的水果NO含量和NO合酶活性较低。总之，脯氨酸和PA显然在1-MCP诱导的桃耐寒性中起直接和重要的作用，而NO可能没有积极参与。