Transcriptome Analysis Reveals the Involvement of Phenylpropane Metabolic Pathway in Cold Tolerance of Cinnamomun bodinieri

Abstract Using Illumina HiSeqTM platform, we analyzed the transcriptomes of one cold-resistant Cinnamomum bodinieri phenotype (CbLY) and three low-temperature-sensitive phenotypes (CbXY, CbMY, and CbYY) under natural low-temperature stress. 3572 DEGs were found in the CbXY_vs_CbLY comparison, 4257 DEGs in the CbMY_vs_CbLY comparison, and 3043 DEGs in the CbYY_vs_CbLY comparison. GO analysis revealed that all three comparisons had significant enrichment of genes involved in defense-related biochemical processes, membrane integrity-related cellular components. Genes related to ADP binding, protein kinase activity, ATP binding, and UDP-glycosyltransferase activity were prominently enriched in molecular function category. KEGG pathway analysis revealed that DEGs across all three comparisons were found to be enriched in the pathways of phenylpropanoid, flavonoid, and anthocyanin biosynthesis. The UDP-glycosyltransferases identified were classified into seven branches using phylogenetic tree analysis, five of which were involved in phenylpropane biosynthesis process, flavonoid biosynthesis pathway and anthocyanin biosynthesis pathway. 42 genes, including PAL, COMT, 4CL, F5H, HCT, C4H, C3H, CHS, FLS, F3H, F3'H, LAR, CCoAOMT, CCR, CAD and POD, which were significantly upregulated in CbLY compared to CbXY, CbMY, and CbYY. Six genes related to phenylpropanoid biosynthesis were randomly selected for real-time fluorescence quantitative PCR. The results of qRT-PCR were consistent with the transcriptome sequencing. Conclusion: The integrity of the inner membrane structure of Cinnamomun bodinieri leaves was damaged by low temperature in winter. The phenylpropane biosynthesis pathway played an important role in Cinnamomun bodinieri’s tolerance to low-temperature stress. PAL, COMT, 4CL, F5H, HCT, C4H, C3H, CHS, FLS, F3H, F3'H, LAR, CCoAOMT, CCR, CAD, POD and UDP-glycosyltransferase are the key genes to improve the cold tolerance in Cinnamomun bodinieri.