Transcription factor PpWRKY13 targets a cell wall modification gene in peach to regulate fruit softening

The postharvest preservation of peach (Prunus persica) fruit has always been a concern, and research on the mechanisms behind peach fruit softening is important for improving postharvest preservation technologies. The WRKY gene family is a multitude of transcription factors in plants that broadly participate in the regulation of various biological processes. Nonetheless, the roles of WRKY family members in peach fruit softening remain largely unknown. Here, we report a peach WRKY family member PpWRKY13 that may be involved in peach fruit softening through the regulation of fruit softening-related gene PpXTH33. Investigations of gene expression levels across different peach organs revealed that PpWRKY13 may play a critical role in peach fruit during storage. A multiple alignment analysis indicated that the PpWRKY13 protein contains a WRKY domain and structural features diagnostic of the Group IIa subfamily. A subcellular localization assay demonstrated that the pBI121-PpWRKY13-EGFP fusion protein is highly localized in the nuclei of tobacco leaf cells, suggesting that PpWRKY13 is characteristic of a transcription factor. We identified a candidate target gene, PpXTH33, of PpWRKY13 using DNA affinity purification sequencing. Additionally, a luciferase assay and transient overexpression suggested that PpWRKY13 may activate the transcription of PpXTH33. In summary, PpWRKY13 may activate the transcription of PpXTH33 and function as a putative modulator of peach fruit softening. This work advances our knowledge of peach fruit softening mechanisms.