title: Characterization of dihydroflavonol 4-reductase (DFR) genes and their association with cold and freezing stress in Brassica rapa.
abstract: Flavonoids including anthocyanins provide flower and leaf colors, as well as other derivatives that play diverse roles in plant development and interactions with the environment. Dihydroflavonol 4-reductase (DFR) is part of an important step in the flavonoid biosynthetic pathway of anthocyanins. This study characterized 12 DFR genes of Brassica rapa and investigated their association with anthocyanin coloration, as well as cold and freezing stress in several genotypes of B. rapa. Comparison of sequences of these genes with DFR gene sequences from other species revealed a high degree of homology. Constitutive expression of the genes in several pigmented and non-pigmented lines of B. rapa demonstrated correlation with anthocyanin accumulation for BrDFR8 and 9. Conversely, BrDFR2, 4, 8 and 9 only showed very high responses to cold stress in pigmented B. rapa samples. BrDFR1, 3, 5, 6 and 10 responded to cold and freezing stress treatments, regardless of pigmentation. BrDFRs were also shown to be regulated by two transcription factors, BrMYB2-2 and BrTT8, contrasting with anthocyanin accumulation and cold and freezing stress. Thus, the above results suggest that these genes are associated with anthocyanin biosynthesis and cold and freezing stress tolerance and might be useful resources for development of cold and/or freezing stress resistant Brassica crops with desirable colors as well. These findings may also facilitate exploration of the molecular mechanism that regulates anthocyanin biosynthesis and its response to abiotic stresses.
authors.affiliation: Department of Horticulture, Sunchon National University, 255 Jungang-ro, Suncheon, Jeonnam 540-950, Republic of Korea.
authors.forename: Nasar Uddin
authors.initials: NU
authors.lastname: Ahmed
authors.affiliation: Department of Horticulture, Sunchon National University, 255 Jungang-ro, Suncheon, Jeonnam 540-950, Republic of Korea.
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Park
authors.affiliation: Department of Horticulture, Sunchon National University, 255 Jungang-ro, Suncheon, Jeonnam 540-950, Republic of Korea.
authors.forename: Hee-Jeong
authors.initials: HJ
authors.lastname: Jung
authors.affiliation: Department of Plant Science, College of Agriculture and Life Sciences, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul 151-921, Republic of Korea.
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Yang
authors.affiliation: Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Yoonkang
authors.initials: Y
authors.lastname: Hur
authors.affiliation: Department of Horticulture, Sunchon National University, 255 Jungang-ro, Suncheon, Jeonnam 540-950, Republic of Korea. Electronic address: nis@sunchon.ac.kr.
authors.forename: Ill-Sup
authors.initials: IS
authors.lastname: Nou
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000429:Alcohol Oxidoreductases / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000378:metabolism; D029741:Brassica rapa / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D003080:Cold Temperature; D005615:Freezing; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D000872:Anthocyanins; D007527:Isoenzymes; D010940:Plant Proteins; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase
keywords: Anthocyanin; Brassica rapa; Cold and freezing stress; Dihydroflavonol 4-reductase (DFR)