Brassinolides (BRs) are phytohormones that play numerous roles in a plants’ response to environmental stress. While BES/BZR transcription factors are essential components in BR signaling, their role in regulating postharvest fruit responses to cold stress is largely unknown. In this study, the application of 24-epibrassinolide (EBR) to peaches alleviated chilling injury (CI) during postharvest cold storage. We further characterized a key BES/BZR gene,PpBZR1, which regulates peach cold resistance. Transient expression PpBZR1in peaches showed that PpBZR1 inhibits PpVIN2 expression and VIN activity, resulting in an elevated level of sucrose, which protects fruit from CI. Arabidopsis expressing PpBZR1 had a high germination and seedling survival rate at low temperatures, which may be due to higher level of sucrose and lower oxidative damage. Mechanistically, we confirmed that PpBZR1 directly binds to the PpVIN2 promoter and functions as a negative regulator. In addition, PpCBF1/5/6 were induced by EBR treatment and AtCBFswere upregulated in transgenic Arabidopsis. Combined with previous findings, we hypothesize that PpBZR1 regulates PpVIN2 through a CBF-dependent manner. In conclusion, PpBZR1 expression is induced by EBR treatment during cold storage, and PpBZR1 futher inhibite sucrose degradation gene PpVIN2transcription via direct binding its promoter and indirectly regulating PpVIN2. This CBF-dependent and CBF-independent regulation results in slower sucrose degradation and higher chilling tolerance of peach.

In this study, isomerization conditions, cytotoxic activity, and stabilization of amygdalin from peach kernels were analyzed. Temperatures greater than 40 °C and pHs above 9.0 resulted in a quickly increasing isomer ratio (L-amygdalin/D-amygdalin). At acidic pHs, isomerization was significantly inhibited, even at high temperature. Ethanol inhibited isomerization; the isomer rate decreased with the ethanol concentration increasing. The growth-inhibitory effect on HepG2 cells of D-amygdalin was diminished as the isomer ratio increased, indicating that isomerization reduces the pharmacological activity of D-amygdalin. Extracting amygdalin from peach kernels by ultrasonic power at 432 W and 40 °C in 80% ethanol resulted in a 1.76% yield of amygdalin with a 0.04 isomer ratio. Hydrogel beads prepared by 2% sodium alginate successfully encapsulated the amygdalin, and its encapsulation efficiency and drug loading rate reached 85.93% and 19.21%, respectively. The thermal stability of amygdalin encapsulated in hydrogel beads was significantly improved and reached a slow-release effect in in vitro digestion. This study provides guidance for the processing and storage of amygdalin.

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