Differential transcriptome analysis of leaves of tea plant (Camellia sinensis) provides comprehensive insights into the defense responses to Ectropis oblique attack using RNA-Seq

Tea is a very popular and healthy nonalcoholic beverage worldwide. As an evergreen woody plant, the cultivation of tea plants (Camellia sinensis) is challenged by biotic stresses, and one of which is feeding of Ectropis oblique. In China, E. oblique infestation causes serious damages in many tea cultivation areas. Tea plants have evolved sophisticated strategies to cope with attack by E. oblique. To elucidate the molecular mechanisms of the response to E. oblique in tea plants, the differential gene expression profiles between the E. oblique damage-induced tea plants and undamaged control using RNA sequencing (RNA-Seq) were obtained. A total of 1859 differentially expressed genes were identified, including 949 upregulated and 910 downregulated genes. Overall, 90 signal transduction genes, 100 anti-insect responsive transcription factors, 50 genes related to phenylpropanoid biosynthesis, 41 unigenes related to herbivore-induced plant volatiles (HIPVs) biosynthesis, and 8 caffeine biosynthesis genes were found to be differentially regulated. Metabolic pathway analysis indicated that plant secondary metabolites and the signaling pathways may play an important role in defense against insects, and a closer examination at the expression of some crucial genes revealed differential expression patterns after feeding by E. oblique. Furthermore, quantitative RT-PCR (qRT-PCR) analysis further confirmed the results of RNA-Seq. Our dataset provides the most comprehensive sequence resource available for studying the resistance to E. oblique in tea, which will benefit our understanding of the overall mechanisms underlying inducible defenses responses, and may be useful to create novel prevention measures against insects to reduce pesticide usage in eco-friendly tea farming.