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- 검색키워드
- 저자 : Paramvir Singh Ahuja (검색결과 2 건)
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Characterization of dihydroflavonol 4-reductase cDNA in tea [Camellia sinensis (L.) O. Kuntze]
Kashmir Singh,Sanjay Kumar,Sudesh Kumar Yadav,Paramvir Singh Ahuja 한국식물생명공학회 2009 Plant biotechnology reports Vol.3 No.1
Tea leaves are major source of catechins— antioxidant flavonoids. Dihydroflavonol 4-reductase (DFR, EC 1.1.1.219) is one of the important enzymes that catalyzes the reduction of dihydroflavonols to leucoanthocyanins, a key ‘‘late’’ step in the biosynthesis of catechins. This manuscript reports characterization of DFR from tea (CsDFR) that comprised 1,413 bp full-length cDNA with ORF of 1,044 bp (115–1,158) and encoding a protein of 347 amino acids. Sequence comparison of CsDFR with earlier reported DFR sequences in a database indicated conservation of 69– 87% among amino acid residues. In silico analysis revealed CsDFR to be a membrane-localized protein with a domain (between 16 and 218 amino acids) resembling the NADdependent epimerase/dehydratase family. The theoretical molecular weight and isoelectric point of the deduced amino sequence of CsDFR were 38.67 kDa and 6.22, respectively. Upon expression of CsDFR in E. coli, recombinant protein was found to be functional and showed specific activity of 42.85 nmol min-1 mg protein-1. Expression of CsDFR was maximum in younger rather than older leaves. Expression was down-regulated in response to drought stress and abscisic acid, unaffected by gibberellic acid treatment, but up-regulated in response to wounding, with concomitant modulation of catechins content. This is the first report of functionality of recombinant CsDFR and its expression in tea. Tea leaves are major source of catechins— antioxidant flavonoids. Dihydroflavonol 4-reductase (DFR, EC 1.1.1.219) is one of the important enzymes that catalyzes the reduction of dihydroflavonols to leucoanthocyanins, a key ‘‘late’’ step in the biosynthesis of catechins. This manuscript reports characterization of DFR from tea (CsDFR) that comprised 1,413 bp full-length cDNA with ORF of 1,044 bp (115–1,158) and encoding a protein of 347 amino acids. Sequence comparison of CsDFR with earlier reported DFR sequences in a database indicated conservation of 69– 87% among amino acid residues. In silico analysis revealed CsDFR to be a membrane-localized protein with a domain (between 16 and 218 amino acids) resembling the NADdependent epimerase/dehydratase family. The theoretical molecular weight and isoelectric point of the deduced amino sequence of CsDFR were 38.67 kDa and 6.22, respectively. Upon expression of CsDFR in E. coli, recombinant protein was found to be functional and showed specific activity of 42.85 nmol min-1 mg protein-1. Expression of CsDFR was maximum in younger rather than older leaves. Expression was down-regulated in response to drought stress and abscisic acid, unaffected by gibberellic acid treatment, but up-regulated in response to wounding, with concomitant modulation of catechins content. This is the first report of functionality of recombinant CsDFR and its expression in tea.
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Amrina Shafi,Insha Zahoor,Tejpal Gill,Paramvir Singh Ahuja,Sanjay Kumar,Anil Kumar Singh 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.3
Antioxidant enzymes, such as superoxide dismutase (SOD) and ascorbate peroxidase (APX), play important role in ROS homeostasis in plants. In the present study, two important antioxidant enzyme-encoding genes, cytosolic Cu/Zn-SOD and APX, were isolated from Potentilla atrosanguinea and Rheum australe plants, which grow at high-altitude regions of Himalaya. Previously, we have reported cytosolic overexpression of both the genes in Arabidopsis, individually and in combination and these transgenic plants exhibit cold and salt stress tolerance. In the present study, wild-type (WT) and transgenic lines (cytosolic Cu/Zn-SOD and APX) were analysed for their regeneration potential and expression profiling of various genes involved in in vitro regeneration was carried out. Among all transgenic lines, dual transgenics showed early callus induction and shoot regeneration. Callus growth rate and in vitro regeneration capacity were significantly higher in transgenic lines compared with control plants. Interestingly, H2O2 accumulation and SOD activity were found to be higher in SOD and dual transgenic lines during callus induction and shoot regeneration stages, indicating a correlation between H2O2 and SOD activity with regeneration process. Whereas APX activity in transgenic lines was found to be decreased in regenerated shoots, cotyledons, it was increased in callus and roots. Further, expression analysis of several genes involved in callus induction and in vitro regeneration using qRT-PCR showed that the majority of genes were significantly up-regulated (two- to fourfold) during different stages of regeneration in transgenic lines. Consequently, our results substantiate that a minimal amount of H2O2 accumulation brought about by overexpression of SOD and APX genes may play an important role in early callus induction and shoot regeneration in transgenic line. The overall results will add knowledge about the role of antioxidant genes in in vitro regeneration of plants.
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