Changes of Phenolic Acids Related Genes in Taraxacum mongolicum Hand.-Mazz. under Saline Stress

Dandelion (Taraxacum mongolicum Hand.-Mazz.) is rich in phenolic acids and has become popular in vegetable and medicine in China. Growing dandelion in saline-alkali land is considered to be an efficient strategy for the development of saline-alkali land. In order to screen candidate genes related to phenolic acids synthesis under saline stress, we evaluated phenolic acids accumulation from dandelion resource of A (T. mongolicum cv. dandelion cultivar “Binpu 2”) and B (T. mongolicum cv. a wild local dandelion “Tanghai”) under NaCl concentrations of 0, 0.3%, 0.5%, 0.7%, 0.9% and 1.2%. Result found that 4 main kinds of phenolic acids that caftaric acid, chlorogenic acid, caffeic acid and chicoric acid all showed the highest accumulations in treatment of 0.9% NaCl for the two dandelions. Thus we performed a transcriptome analysis of dandelion leaves at the NaCl concentration of 0.9%. Totally 2468 differentially expressed genes (DEGs) were detected from dandelion A, including 1456 up-regulated DEGs; and the total 3238 with 1369 up-regulated DEGs were found in dandelion B. GO annotation analysis showed that the functions of DEGs were mainly referred to phenylpropanoid biosynthesis process, secondary metabolite biosynthetic process, apoplast, etc. KEGG enrichment showed that DEGs were enriched in secondary metabolites biosynthesis, phenylpropanoid biosynthesis, plant hormone signal transduction, etc. We specially analyzed the DEGs of caffeic acid O-methyltransferase due to the highest content accumulated in dandelions, and found 4 DEGs related to O-methyltransferase 1 (OMT1), including 2 novel genes. We validated the expression profiles of the four candidate OMT1 genes by qRT-PCR, and found the results were consistent with the RNA-seq results.