The phytocytokine systemin enhances postharvest tomato fruit resistance to Botrytis cinerea

Abstract

The 18-amino acid peptide systemin is the first identified phytocytokine and plays important roles in tomato resistance to pathogens and insects. However, the function of systemin in postharvest fruit is unknown. Here, we found pretreatment of systemin increased the resistance of postharvest tomato fruit to Botrytis cinerea and the resistance ability was dependent on the concentration of systemin. As a phytocytokine, systemin induced the early immune responses in postharvest fruit, including the expression of immune-related genes, activation of mitogen-activated protein kinases (MAPKs), and production of reactive oxygen species. Transcriptome results indicated that systemin enhanced the expression of genes in the MAPK signaling pathway, phenypropanoid biosynthesis pathway and fatty acid desaturase (FAD) genes. Moreover, systemin regulated the activity of chitinase, phenylalanine ammonia lyase and peroxidase, and the concentration of FAD2 during storage. Therefore, our findings suggested that systemin could be a promising molecule to increase tomato fruit resistance against pathogens during storage.