3.8 Postharvest trehalose treatment up-regulates PpINH1and increases chilling resistance of peach fruit
CI in peaches occurred after two weeks of storage at 5 °C. Visible flesh browning was observed on day 21 of storage, and at day 28 severe CI was observed. In contrast, peaches treated with trehalose did not exhibit substantial CI after 21 or 28 days of storage (Figure 6a, 6b ). Sucrose content in trehalose-treated fruit was significantly higher than in untreated control fruit throughout the 28-day storage period (Figure 6c ). In control fruit, VIN activity increased nearly 2-fold during 28 days of cold storage (Figure 6d ), whilePpVIN2 expression increased more than 500-fold by the 21st day of storage (Figure 6e ). In trehalose-treated fruit, VIN activity also increased during storage, but remained lower than in the control fruit. PpVIN2 expression also increased with storage time but was significantly lower than in control fruit on days 21 and 28. Expression of PpINH1 in control fruit decreased significantly during storage, as did expression in trehalose-treated fruit, but PpINH1 expression in treated peaches remained significantly higher throughout cold storage (Figure 6f ).