Transcriptome analyses revealed molecular responses of Cynanchum auriculatum leaves to saline stress

Cynanchum auriculatum is a traditional herbal medicine in China and can grow in saline soils. However, little is known in relation to the underlying molecular mechanisms. In the present study, C. auriculatum seedlings were exposed to 3.75‰ and 7.5‰ salinity. Next, transcriptome profiles of leaves were compared. Transcriptome sequencing showed 35,593 and 58,046 differentially expressed genes (DEGs) in treatments with 3.75‰ and 7.5‰, compared with the control, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of these DEGs enriched various defense-related biological pathways, including ROS scavenging, ion transportation, lipid metabolism and plant hormone signaling. Further analyses suggested that C. auriculatum up-regulated Na(+)/H(+) exchanger and V-type proton ATPase to avoid accumulation of Na(+). The flavonoid and phenylpropanoids biosynthesis pathways were activated, which might increase antioxidant capacity in response to saline stress. The auxin and ethylene signaling pathways were upregulated in response to saline treatments, both of which are important plant hormones. Overall, these results raised new insights to further investigate molecular mechanisms underlying resistance of C. auriculatum to saline stress.