title: Patterns of evolutionary conservation of ascorbic acid-related genes following whole-genome triplication in Brassica rapa.
abstract: Ascorbic acid (AsA) is an important antioxidant in plants and an essential vitamin for humans. Extending the study of AsA-related genes from Arabidopsis thaliana to Brassica rapa could shed light on the evolution of AsA in plants and inform crop breeding. In this study, we conducted whole-genome annotation, molecular-evolution and gene-expression analyses of all known AsA-related genes in B. rapa. The nucleobase-ascorbate transporter (NAT) gene family and AsA l-galactose pathway genes were also compared among plant species. Four important insights gained are that: 1) 102 AsA-related gene were identified in B. rapa and they mainly diverged 12-18 Ma accompanied by the Brassica-specific genome triplication event; 2) during their evolution, these AsA-related genes were preferentially retained, consistent with the gene dosage hypothesis; 3) the putative proteins were highly conserved, but their expression patterns varied; and 4) although the number of AsA-related genes is higher in B. rapa than in A. thaliana, the AsA contents and the numbers of expressed genes in leaves of both species are similar, the genes that are not generally expressed may serve as substitutes during emergencies. In summary, this study provides genome-wide insights into evolutionary history and mechanisms of AsA-related genes following whole-genome triplication in B. rapa.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Weike
authors.initials: W
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Song
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Tongkun
authors.initials: T
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Zhinan
authors.initials: Z
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China.
authors.forename: Xilin
authors.initials: X
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, People's Republic of China.
authors.forename: Jianchang
authors.initials: J
authors.lastname: Du
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture of Nanjing Agricultural University, People's Republic of China yingli@njau.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D001205:Ascorbic Acid / Q000235:genetics* / Q000378:metabolism; D029741:Brassica rapa / Q000235:genetics*; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D058977:Molecular Sequence Annotation; D010802:Phylogeny; D011123:Polyploidy
chemical_list: D001205:Ascorbic Acid
keywords: AsA-related genes; Brassica rapa; evolutionary conservation; expression pattern; gene dosage hypothesis; synteny analysis