Stony hard (SH) peaches undergo minimal softening on the tree or after harvest in air at room temperature. Instead, the firmness of SH peach fruit is reduced by treatments with ethylene or auxin or storage at 10 °C. In this study, the SH peach cultivar ‘Manami’ was stored at 0 °C, 5 °C, 8 °C, 10 °C, 15 °C, 18 °C, and 20 °C to characterize fruit softening with storage temperature. Fruit firmness was effectively reduced with storage at 8 °C, 10 °C, and 15 °C, with softening occurring, even in fruit with lower ethylene production, at 15 °C. In these fruit tissues, expression of a cell wall-modifying enzyme gene coding for polygalacturonase (PG) was identified (PpPGM), which is related to fruit firmness. The duration and sequence of different softening treatments were also examined. Fruit stored at 10 °C for 6 d prior to cold storage (0 °C) continued to soften after storage, and PpPGM was expressed in these tissues during cold storage. However, fruit stored at 0 °C or 20 °C for longer than 2 w did not soften during subsequent treatment at 10 °C. These results indicate that temperature-induced fruit softening, for example, within 7 d of treatment and during storage at 15 °C, occurred under conditions of lower ethylene production and may be partly attributed to ethylene-independent PG induction. Thus, PG expression might be an important factor for SH peach fruit softening during or after storage.

石质 (SH) 桃子在树上或在室温下在空气中收获后几乎不会软化。相反，用乙烯或生长素处理或在 10 °C 下储存会降低 SH 桃果实的硬度。在本研究中，SH 桃品种“Manami”在 0 °C、5 °C、8 °C、10 °C、15 °C、18 °C 和 20 °C 下储存，以表征果实软化与储存温度。在 8 °C、10 °C 和 15 °C 下储存时，果实的硬度会有效降低，即使在 15 °C 下乙烯产量较低的果实中也会发生软化。在这些果实组织中，鉴定了编码多聚半乳糖醛酸酶 ( PG ) 的细胞壁修饰酶基因的表达( PpPGM)，这与果实的硬度有关。还检查了不同软化处理的持续时间和顺序。冷藏（0°C）前在 10°C 下储存 6 天的果实在储存后继续软化，并且在冷藏期间PpPGM在这些组织中表达。然而，在 0 °C 或 20 °C 下储存超过 2 w 的水果在随后的 10 °C 处理期间没有软化。这些结果表明，温度引起的果实软化，例如，在处理 7 d 内和在 15°C 下储存期间，发生在乙烯产量较低的条件下，可能部分归因于不依赖乙烯的PG诱导。因此，PG表达可能是贮藏期间或贮藏后 SH 桃果实软化的重要因素。