title: Differential effects of ornithine enantiomers on the activity of anti-oxidant enzymes, polyamines content, and growth of tobacco cells under osmotic stresses.
abstract: Ornithine (Orn) plays an essential role in the metabolism of plant cells through incorporation in polyamines biosynthesis, the urea cycle and nitrogen metabolism. Herein, we show that Orn enantiomers have different effects on anti-oxidant enzymes activities, polyamines and proline biosynthesis and also an alleviation effect of osmotic stresses on tobacco cells. The type of stress has a significant impact on the function of L- and D-Orn for improvement of the stress effect on the cells. Under saline conditions, both enantiomers restored cell growth, though D-Orn was more beneficial to some extent. This was accompanied with a higher biosynthesis of putrescine, proline, and up-regulated activity of certain anti-oxidant enzymes by D-Orn. Under drought stress conditions, a distinct differential behavior emerged and only L-Orn showed an alleviative effect on the cell growth. Regulation of hydrogen peroxide content via the activity of catalase/peroxidase and production of osmolytes, e.g., proline and fructans, was dependent on the type of enantiomers. Activity of anti-oxidant enzymes and production of malondialdehyde from cell membranes were differently regulated following treatment with either Orn enantiomer. The results suggest that management of H2 O2 content is a determining feature of the function of Orn enantiomers in tobacco cells under salinity and drought stress conditions.
authors.affiliation: Medicinal Plants and Drugs Research Institute (MPDRI), Shahid Beheshti University, G.C., P.O.1983963113, Tehran, Iran.
authors.forename: Morteza
authors.initials: M
authors.lastname: Gholami
authors.forename: Faezeh
authors.initials: F
authors.lastname: Ghanati
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Fakhari
authors.forename: Laleh
authors.initials: L
authors.lastname: Yousefzadeh Borojeni
authors.forename: Masoumeh
authors.initials: M
authors.lastname: Safari
mesh_terms: D002374:Catalase / Q000737:chemistry; D004789:Enzyme Activation / Q000187:drug effects; D005630:Fructans / Q000737:chemistry; D009952:Ornithine / Q000737:chemistry* / Q000494:pharmacology; D009997:Osmotic Pressure / Q000187:drug effects*; D010544:Peroxidases / Q000737:chemistry; D011073:Polyamines / Q000737:chemistry*; D011392:Proline / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D005630:Fructans; D011073:Polyamines; D011392:Proline; D009952:Ornithine; D010544:Peroxidases; D002374:Catalase
keywords: (L/D)-ornithine; D-amino acids; osmotic stress; oxidative burst; polyamines