title: Polyamine metabolism influences antioxidant defense mechanism in foxtail millet (Setaria italica L.) cultivars with different salinity tolerance.
abstract: Polyamines can regulate the expression of antioxidant enzymes and impart plants tolerance to abiotic stresses. A comparative analysis of polyamines, their biosynthetic enzymes at kinetic and at transcriptional level, and their role in regulating the induction of antioxidant defense enzymes under salt stress condition in two foxtail millet (Setaria italica L.) cultivars, namely Prasad, a salt-tolerant, and Lepakshi, a salt-sensitive cultivar was conducted. Salt stress resulted in elevation of free polyamines due to increase in the activity of spermidine synthase and S-adenosyl methionine decarboxylase enzymes in cultivar Prasad compared to cultivar Lepakshi under different levels of NaCl stress. These enzyme activities were further confirmed at the transcript level via qRT-PCR analysis. The cultivar Prasad showed a greater decrease in diamine oxidase and polyamine oxidase activity, which results in the accumulation of polyamine pools over cultivar Lepakshi. Generation of free radicals, such as O 2 (·-) and H2O2, was also analyzed quantitatively. A significant increase in O 2 (·-) and H2O2 in the cultivar Lepakshi compared with cultivar Prasad was recorded in overall pool sizes. Further, histochemical staining showed lesser accumulation of O 2 (·-) and of H2O2 in the leaves of cultivar Prasad than cultivar Lepakshi. Our results also suggest the ability of polyamine oxidation in regulating the induction of antioxidative defense enzymes, which involve in the elimination of toxic levels of O 2 (·-) and H2O2, such as Mn-superoxide dismutase, catalase and ascorbate peroxidase. The contribution of polyamines in modulating antioxidative defense mechanism in NaCl stress tolerance is discussed.
authors.affiliation: Plant Molecular Biology Unit, Department of Botany, Sri Krishnadevaraya University, Anantapur, 515 003, India, chintasudhakar@yahoo.com.
authors.forename: Chinta
authors.initials: C
authors.lastname: Sudhakar
authors.forename: Gounipalli
authors.initials: G
authors.lastname: Veeranagamallaiah
authors.forename: Ambekar
authors.initials: A
authors.lastname: Nareshkumar
authors.forename: Owku
authors.initials: O
authors.lastname: Sudhakarbabu
authors.forename: M
authors.initials: M
authors.lastname: Sivakumar
authors.forename: Merum
authors.initials: M
authors.lastname: Pandurangaiah
authors.forename: K
authors.initials: K
authors.lastname: Kiranmai
authors.forename: U
authors.initials: U
authors.lastname: Lokesh
mesh_terms: D012437:Adenosylmethionine Decarboxylase / Q000235:genetics / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055049:Salt Tolerance; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D032983:Setaria Plant / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D013045:Species Specificity; D011436:Spermidine Synthase / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D000097667:Polyamine Oxidase
chemical_list: D012437:Adenosylmethionine Decarboxylase; D000975:Antioxidants; D002374:Catalase; D006861:Hydrogen Peroxide; D000587:Oxidoreductases Acting on CH-NH Group Donors; D011073:Polyamines; D012965:Sodium Chloride; D011436:Spermidine Synthase; D013482:Superoxide Dismutase; D013481:Superoxides; D000097667:Polyamine Oxidase