Transcriptomic and proteomic analyses of leaves from Clematis terniflora DC. under high level of ultraviolet-B irradiation followed by dark treatment

Abstract

High level of UV-B irradiation followed by dark treatment (HUV-B+D) causes accumulation of secondary metabolites in Clematis terniflora DC. To investigate the response mechanism under HUV-B+D, transcriptomic and proteomic analyses were performed in leaves of C. terniflora. The number of genes related to tetrapyrrole synthesis, amino acid metabolism, tricarboxylic acid cycle, and mitochondrial electron transport chains was hierarchically changed in leaves of C. terniflora under HUV-B+D. Data from RNA-sequencing transcriptomics and gel-free/label-free proteomics were integrated. The genes related to biosynthesis of lignins and flavonoids/isoflavonoids were significantly upregulated. Luteolin 7-O-β-D-glucosiduronic acid, rutin, and kaempferol 3-O-rutinose were accumulated. The number of differentially expressed genes (DEGs) and differentially abundant proteins (DAPs) related to protein metabolism were largely changed in posttranslational modification, ubiquitin proteasome, and ribosomal protein. The expression of NADP-dependent malic enzyme and the abundance of NADP-malate dehydrogenase were upregulated and increased, respectively. The activities of these two enzymes were also enhanced. These results suggest that the secondary metabolism pathway and tricarboxylic acid cycle might be activated in leaves of C. terniflora in response to HUV-B+D.

Biological significance: This study reported response mechanism in leaves of Clematis terniflora DC. under high level of UV-B irradiation followed by dark treatment using transcriptomic and proteomic techniques. Transcriptomic analysis revealed that the number of genes related to secondary metabolism was increased by >2 times. Phenylalanine ammonia-lyase, 4-Coumarate: CoA ligase, chalcone synthase, isoflavone reductase homolog, and cinnamoyl-CoA reductase were significantly upregulated, which suggests that the secondary metabolism pathway related to lignins and flavonoids/isoflavonoids might be activated. Genes and proteins related to protein metabolism were largely changed in postranslational modification, ubiquitin proteasome, and ribosomal protein. NADP-dependent malic enzyme and NADP-malate dehydrogenase were activated in tricarboxylic acid cycle, which suggests that tricarboxylic acid cycle might be enhanced in leaf of C. terniflora in response to HUV-B+D.

Keywords: Clematis terniflora DC.; Dark treatment; Proteomics; Transcriptomics; Ultraviolet-B irradiation.