Materials and methods
Plant materials and treatments
Red flesh peach (Prunus persica  L. Batsch cv. Tianxianhong) (He et al., 2010) fruits with consistent color, shape and weight were harvested at commercial maturity from an orchard in Xiaogan, Hubei province, China. Uniform fruits without visual defects were selected and kept at 5 °C for 2 days after the day of harvest. Then, these fruits were randomly divided into two groups. One group was stored at CT for 7 days, and the other was stored at HT for 7 days. During shelf life, fruits were sampled at day 1, 2 and 3 as early stage as well as day 5, 6 and 7 as later stage. For each sampling point, sarcocarp was extracted and randomly distributed into two biological replicates. Then, mesocarp was sliced, frozen in liquid nitrogen and stored at -80 °C for further study.
Measurements ofphysiological changes
Some physiological parameters were measured for each sample during storage. GY-2 fruit hardness tester with a 3.5-mm-diameter head was applied to measure the pulp firmness of fruit without peel. Six peach fruits from each sample were selected, and 7 points evenly distributed over each fruit were examined and the mean of the measured values was calculated and used. To detect ethylene production, 1 kg of fruits from each sample were selected and preserved in a sealed box at the same temperature for 6 h, then 1 ml gas sample was collected to measure ethylene production using gas chromatography (Agilent Technologies 7890A GC System, USA) with 3 biological replicates. The gas chromatographic (GC) analysis of ethylene used GC Columns (30 m × 0.530 nm × 3.00 µm), and oven, inlet and detector temperatures were 40 °C, 250 °C and 250 °C, respectively. The ethylene standard curve was plotted with the gradients of 5 concentration values to identify the ethylene production rate. The 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase were extracted to measure their activities using conventional method.