title: AtROS1 overexpression provides evidence for epigenetic regulation of genes encoding enzymes of flavonoid biosynthesis and antioxidant pathways during salt stress in transgenic tobacco.
abstract: In plants, epigenetic changes have been identified as regulators of developmental events during normal growth as well as environmental stress exposures. Flavonoid biosynthetic and antioxidant pathways play a significant role in plant defence during their exposure to environmental cues. The aim of this study was to unravel whether genes encoding enzymes of flavonoid biosynthetic and antioxidant pathways are under epigenetic regulation, particularly DNA methylation, during salt stress. For this, a repressor of silencing from Arabidopsis, AtROS1, was overexpressed in transgenic tobacco. Generated transgenics were evaluated to examine the influence of AtROS1 on methylation status of promoters as well as on coding regions of genes encoding enzymes of flavonoids biosynthesis and antioxidant pathways. Overexpression of AtROS1 increases the demethylation levels of both promoters as well as coding regions of genes encoding chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, flavonol synthase, dihydroflavonol 4-reductase, and anthocyanidin synthase of the flavonoid biosynthetic pathway, and glutathione S-transferase, ascorbate peroxidase, glutathione peroxidase, and glutathione reductase of the antioxidant pathway during control conditions. The level of demethylation was further increased at promoters as well as coding regions of these genes during salt-stress conditions. Transgenic tobacco overexpressing AtROS1 showed tolerance to salt stress that could have been due to the higher expression levels of the genes encoding enzymes of the flavonoid biosynthetic and antioxidant pathways. This is the first comprehensive study documenting the epigenetic regulation of flavonoid biosynthetic and antioxidant pathways during salt-stress exposure of plants.
authors.affiliation: Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himanchal Pradesh, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Bharti
authors.affiliation: Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himanchal Pradesh, India.
authors.forename: Monika
authors.initials: M
authors.lastname: Mahajan
authors.affiliation: Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himanchal Pradesh, India.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Vishwakarma
authors.affiliation: Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himanchal Pradesh, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Bhardwaj
authors.affiliation: Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himanchal Pradesh, India skyt@rediffmail.com.
authors.forename: Sudesh Kumar
authors.initials: SK
authors.lastname: Yadav
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D044127:Epigenesis, Genetic; D005419:Flavonoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D005419:Flavonoids; D009687:Nuclear Proteins; C471271:ROS1 protein, Arabidopsis; D012965:Sodium Chloride
keywords: Epigenetic regulation; ROS1 overexpression; coding regions; methylation status; promoters; salt stress; tobacco.