Transcriptome changes and its effect on physiological and metabolic processes in tea plant during mechanical damage

Mechanical damage affects tea plant growth and the quality of tea-leaf products. However, data on the wound response of tea leaves at the transcriptome level remain scarce. In this study, the transcriptome of wound-induced tea leaves was analysed by RNA-Seq and some of their secondary metabolites were determined using high-performance liquid chromatography (HPLC) technology. The results showed that 129610 non-redundant transcripts and 60361 unigenes were obtained, of which 100834 transcripts (77.80% of all transcripts) were annotated by sequence similarity searching against public databases and 28776 transcripts could be potentially new genes or novel transcripts from selective splicing. A total of 19214 differentially expressed transcripts (DETs) were selected from the data set. DET functions involved various physiological and molecular biological processes in tea plant including various transcripts encoding protease inhibitors (PIs), pathogenesis-related proteins (PRs) and enzymes related to catechin, caffeine and terpenoid metabolic pathways. Moreover, the contents of some polyphenols and caffeine were also validated in tea leaves after an increase in wounding. The transcriptome analysis revealed a reprogramming process in tea plants during wounding that involved various physiological and molecular biological processes, which can increase the resistance of plants against biotic and abiotic stress and affect the quality of tea-leaf products. Our results not only provide systematic insight into the defence responses in tea plants during mechanical damage, but also are beneficial for the scientific cultivation of tea.