Influence of Different Low-Temperature Treatments on Chilling Injury and Accumulation of Characteristic Anthocyanins...

Low-temperature storage causes chilling injury (CI) in pomegranate fruit and influences anthocyanin accumulation. However, the exploration of characteristic anthocyanins in pomegranates and their association with CI remains poorly understood. In this study, the "Acid" variety displayed fewer CI symptoms, a lower rate of weight loss, and higher redness intensity compared to "Soft seeds" and "Six-month red". Peel anthocyanin content declined during cold storage, with a slower decrease at 10 °C than that at 4 °C. However, storage at 4 °C reduced the aril anthocyanin content in "Six-month red" and "Soft seeds" pomegranates, but promoted its accumulation in "Acid". At 10 °C, aril anthocyanin in "Six-month red" was unaffected, whereas accumulation was observed in "Soft seeds" and "Acid". Analysis identified 103 anthocyanins in total, 25 of which were common to both peel and aril. Cyanidin-3,5-O-diglucoside and pelargonidin-3,5-O-diglucoside were present in both the peel and aril of "Six-month red" and "Acid" varieties, with higher contents than in "Soft seeds". Low temperature affected both characteristic anthocyanins and key synthesis genes (PgDFR, PgUFGT, PgANS, PgF3'H, PgCHI), with effects consistent with those on total anthocyanins. The "Acid" variety exhibits high cold tolerance, which alleviates peel anthocyanin degradation and promotes aril anthocyanin accumulation. These findings will contribute to elucidating the mechanisms underlying cold tolerance in pomegranates and provide new insights for pomegranate breeding.