Abstract:

To explore the role of SUMO E3 ligase（SIZ1）gene in chilling injury incidence of postharvest peach fruit，PpSIZ1 gene was identified and analyzed by bioinformatics. Furthermore，the effects of low temperature storage and exogenous melatonin treatments on PpSIZ1 expression were investigated in‘Hujing Milu’peach fruit during storage. Results showed that SIZ1 gene was identified in the peach genome and named as PpSIZ1，and the ORF of PpSIZ1 was 2 637 bp which encoded a predicted protein of 878 amino acids. Phylogenetic analysis indicated that PpSIZ1shared high similarity homology with PmSIZ1. Bioinformatics analysis showed that PpSIZ1 possessed predicted SAP，PHD，PINIT，SP-RING，and SXS domains，which were highly conserved in AtSIZ1，indicated PpSIZ1 could be classified with SUMO E3 Ligase. Chilling injury index of the fruit stored at 0 ℃ increased with the prolongation of storage. Exogenous melatonin treatments（100 and 200 μmol · L^-1）could significantly inhibited chilling injury incidence of peach fruit stored at 0 ℃，and 100 μmol · L^-1 melatonin treatment exhibits the best inhibitory effect. Low temperature stress at 0 ℃ could induce the expression of PpSIZ1，and the transcription level of PpSIZ1 was strongly up-regulated when treated with 100 μmol · L^-1 melatonin. These results suggest that PpSIZ1 protein possibly functioned as SUMO E3 ligase that facilitated the SUMO modification pathway，which could be associated with chilling tolerance in cold-stored peach fruit.

Key words: peach, fruit, chilling injury, melatonin, PpSIZ1, SUMO E3 ligase