title: Systematic analysis of O-methyltransferase gene family and identification of potential members involved in the formation of O-methylated flavonoids in Citrus.
abstract: The O-methylation of various secondary metabolites is mainly catalyzed by S-adenosyl-l-methionine (SAM)-dependent O-methyltransferase (OMT) proteins that are encoded by the O-methyltransferase gene family. Citrus fruits are a rich source of O-methylated flavonoids that have a broad spectrum of biological activities, including anti-inflammatory, anticarcinogenic, and antiatherogenic properties. However, little is known about this gene family and its members that are involved in the O-methylation of flavonoids and their regulation in Citrus. In this study, 58 OMT genes were identified from the entire Citrus sinensis genome and compared with those from 3 other representative dicot plants. A comprehensive analysis was performed, including functional/substrate predictions, identification of chromosomal locations, phylogenetic relationships, gene structures, and conserved motifs. Distribution mapping revealed that the 58 OMT genes were unevenly distributed on the 9 citrus chromosomes. Phylogenetic analysis of 164 OMT proteins from C.sinensis, Arabidopsis thaliana, Populus trichocarpa, and Vitis vinifera showed that these proteins were categorized into group I (COMT subfamily) and group II (CCoAOMT subfamily), which were further divided into 10 and 2 subgroups, respectively. Finally, digital gene expression and quantitative real-time polymerase chain reaction analyses revealed that citrus OMT genes had distinct temporal and spatial expression patterns in different tissues and developmental stages. Interestingly, 18 and 11 of the 27 genes predicted to be involved in O-methylation of flavonoids had higher expression in the peel and pulp during fruit development, respectively. The citrus OMT gene family identified in this study might help in the selection of appropriate candidate genes and facilitate functional studies in Citrus.
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China; Post-doctoral Station of Horticulture, Southwest University, Chongqing 400715, China. Electronic address: lxgg16853@163.com.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: wodeaily7@163.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: 1003925334@qq.com.
authors.forename: Hongkun
authors.initials: H
authors.lastname: Wu
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: xwp1999@zju.edu.cn.
authors.forename: Wanpeng
authors.initials: W
authors.lastname: Xi
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: yujie1978@126.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: swuzqy@163.com.
authors.forename: Qiuyun
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715, China. Electronic address: zqzhou2013@swu.edu.cn.
authors.forename: Zhiqin
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D032084:Citrus sinensis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D005419:Flavonoids / Q000096:biosynthesis* / Q000737:chemistry; D029761:Garcinia cambogia / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018745:Genome, Plant; D008745:Methylation; D005810:Multigene Family; D009928:Organ Specificity; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011497:Protein O-Methyltransferase / Q000145:classification* / Q000235:genetics* / Q000378:metabolism
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D011497:Protein O-Methyltransferase
keywords: Citrus; Digital gene expression profiling; Expression analysis; O-methylated flavonoids; O-methyltransferase gene family