[Identification and analysis of CmOMT gene family in Chrysanthemum morifolium]

Chrysanthemum morifolium is rich in hydroxyflavonoids and methoxyflavonoids(OMFs), and dissecting the biosynthetic pathway of OMFs in Ch. morifolium is of great theoretical and economic value because of the diverse physiological activities and pharmacological effects of OMFs. To investigate the biosynthetic pathway of OMFs in Ch. morifolium, this study systematically analyzed the CmOMT gene family based on the whole genome data of Ch. morifolium by using bioinformatics approaches. The results showed that 123 CmOMT genes were identified in the genome of Ch. morifolium, encoding 112-541 amino acid residues. The putative proteins had the isoelectric points ranging from 4.92 to 7.59, relative molecular mass ranging from 12 651.69 to 61 300.23. Except CmOMT50, the rest 122 proteins were acidic and 79 of them were hydrophilic. CmOMTs predominantly existed in the cytoplasm with uneven distribution. Seven pathways were enriched by the Kyoto Encyclopedia of Genes and Genomes(KEGG) analysis, including metabolism, phenylpropanoid biosynthesis, and isoflavonoid biosynthesis. The Gene Ontology(GO) enrichment results showed that the 123 CmOMT genes were annotated to 42 GO terms of 12 molecular functions(such as O-methyltransferase activity and S-adenosylme-thanethionine-dependent methyltransferase activity) and 27 biological processes(such as methylation and flavonoid metabolism processes). The prediction results of the cis-acting elements in the promoter region suggested that the CmOMT gene family was involved in the responses to multiple biotic and abiotic stress conditions including light, drought, low temperature, methyl jasmonate, and abscisic acid. In addition, the promoters of CmOMT genes had MYB binding sites involved in the regulation of genes for flavonoid biosynthesis. The analysis of the CmOMT gene family provides a reference for deciphering the biosynthetic pathway of OMFs in Ch. morifolium and lays a foundation of the subsequent mining and functional validation of candidate OMT genes in C. morifolium.