Transcriptomics integrated with metabolomics analysis of cold-induced lenticel disorder via the lignin pathway upon postharvest ‘Xinli No.7’ pear fruit

Pear fruit often suffer severe lenticel disorder in the peel during cold storage, affecting their appearance and commercial value. Pear (Pyrus bretschneideri Rehder cv. Xinli No.7) fruit were treated with ethylene or 1-methylcyclopropene and stored at 0 °C for 28 weeks (air treatment was used as a control). Observations revealed that the lenticels expanded and protruded, resulting rougher pear surface during storage. Furthermore, the occurrence of lenticel disorder was closely related to the lignin biosynthesis. Results from RNA-seq and weighted gene co-correlation network analysis showed a positive relationship among gene expression of lignin biosynthesis, plant hormone transduction, and the occurrence pattern of lenticel disorder. The results showed an increase in lignin biosynthesis through the upregulation of transcription factors and genes involved in the transduction of plant hormones, including ethylene and jasmonic acid. These results provide new insights into the mechanisms of lenticle disorder in ‘Xinli No.7’ pears under cold stress, and offer a theoretical basis for the maintenance of fruit quality during storage.