Transcriptomic analysis reveals the molecular mechanisms of Camellia sinensis in response to salt stress

Tea plant [Camellia sinensis (L.) O. Kuntze] constitutes one of the most important economic crops in many countries. However, in many areas, tea plants are subjected to high salinity, which severely affects the growth and development of these plants. To understand the potential molecular mechanisms of tea plants in response to salt stress, we used RNA-Seq technology to compare the transcriptomes from tea plants treated with and without NaCl and analyzed the differentially expressed genes (DEGs). In total, 470,738 transcripts and 150,257 unigenes were obtained that had average lengths of 1422.09 and 680.40 nt, respectively, and 28,831 of these sequences were annotated in public databases. In addition, 1769 DEGs were identified, including 947 up-regulated and 822 down-regulated ones. Many of these DEGs were involved in Ca2+ signal transduction, the abscisic acid (ABA) pathway, and mitogen-activated protein kinase (MAPK) cascades. Many DEGs were also transcription factors and key functional proteins involved in salt resistance in tea plants; these genes constitute a regulatory network in response to salt stress. qRT-PCR analyses of nine unigenes were performed to confirm the validity of the data, and the results were highly consistent with the RNA-Seq results. Taken together, these findings reveal the underlying molecular mechanism of tea plants in response to salt stress and could provide many candidate genes for additional studies, especially those involving the genetic engineering and breeding of tea plants that are highly resistant to salt stress.