Exploring the effects of pectate and pectate lyase on the fruit softening and transcription profiling of Solanum lycopersicum

In this study, the effects of pectate and pectate lyase (PL) on nutritional quality of tomato fruits were investigated. During postharvest storage, pectate increased the fruit firmness and changed biochemical indicators such as water-soluble pectin (WSP) content and peroxidase activity (POD), simultaneously. RNA-Seq analysis and functional annotation showed that the majority of differentially expressed genes (DEGs) distributed in amino acid metabolism, carbohydrate metabolism, signal transduction pathways in either pectate or PL groups. In view of the opposite effects of pectate and PL on fruit postharvest physiology, 56 DEGs with opposite expression trend were considered to be involved in fruit softening. Subsequently, the qRT- PCR results indicated that transcription of SlPME2.1, SlCHI19, SlMal d1 and SlPR-4B related to cell wall tissue or biogenesis as well as pathogenesis were regulated by pecate and PL. The results help clarify the mechanism of pectate treatment on improving the softening of postharvest tomato fruits.