Abstract

Chilling injury (CI) severely limits the postharvest storage quality of loquat fruit during cold storage. Phytosulfokine α (PSKα) has been shown to effectively enhance cold tolerance of loquat fruit. Nevertheless, it remains unclear whether PSKα alleviates CI via regulating reactive oxygen species (ROS) homeostasis, and the underlying molecular mechanism remains unknown. In this study, PSKα treatment significantly suppressed ROS accumulation through increasing the activities and upregulating the gene expression of key ROS scavenging-related enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR). Bioinformatic analysis revealed that the promoters of these antioxidant-related genes contained (T/A)GATA(A/G) motifs specifically recognized by GATA transcription factors. Among 36 EjGATA genes identified in loquat, EjGATA25 was screened out as differentially expressed, being significantly upregulated by PSKα and showing the strongest correlation with CI symptoms and ROS homeostasis in loquat fruit. Further investigation demonstrated that EjGATA25 could directly bind to (T/A)GATA(A/G) motifs in the promoters of EjCAT1-like , EjAPX , and EjGR , thereby activating their transcription. Collectively, our findings revealed that PSKα treatment could maintain ROS homeostasis by potentiating EjGATA25-mediated transcriptional activation of ROS scavenging-related genes, thereby improving cold tolerance in loquat fruit.