A peach esterase/lipase mediates lipid remodeling as a protective mechanism against chilling injury

Peach fruit is highly susceptible to chilling injury, which induces internal browning during long-term low-temperature storage. Internal browning was found to occur only at intermediate temperatures (5, 8, and 12 °C), but not at either lower (0 °C) or higher (16 °C) temperatures. Proteomic analysis of peach fruit stored at different temperatures for various durations was performed, and a GDSL esterase/lipase, PpGELP18, a protein with in vitro esterase/lipase activity, was identified. Transgenic tobacco (Nicotiana tabacum) overexpressing PpGELP18 demonstrated enhanced chilling tolerance. Lipidomic analysis of transgenic tobacco (N. tabacum) leaves and peach fruit revealed that PpGELP18 is involved in intracellular lipid remodeling, particularly in the accumulation of membrane phospholipids. Elevated levels of unsaturated phosphatidylcholines and phosphatidylethanolamines, along with a decrease in lysophospholipids and diacylglycerols, were observed in transgenic tobacco (N. tabacum). In contrast, a decrease in phospholipids and an increase in diacylglycerols occurred in peach fruit at chilling-injury-inducing temperatures and during the late storage period at 5 °C, accompanied by internal browning. Ultrastructural examination confirmed that chilling-injury-associated internal browning was accompanied by damage to the plasma membrane and tonoplast. These results demonstrate that elevated PpGELP18 confers chilling tolerance in both peach fruit and tobacco (N. tabacum) plants by modulating lipid composition.