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    BIOCHEMICAL EFFECTS OF ARSENIC STRESS IN THE LEAVES OF HALOPHYTE Cakile maritima (SCOP.) PLANTS UNDER SALINITY
    (Parlar Scientific Publications (P S P), 2013) Demir, Emel; Dinler, Burcu Seckin; Ozdener, Yasemin
    The aim of the study was to determine the biochemical responses which were not investigated before, the combined effects of arsenic and salt stress in the leaves of Cakile maritima (Scop.). Therefore, product of lipit peroxidation (MDA, malondialdehyde), proline content, nonprotein thiol, ascorbate, dehydroascorbate and the activity of some antioxidant enzymes as ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6) were reported. The MDA content was increased at 24 h but it was more at 96 h under salt stress alone. Otherwise the combined effect of arsenic and salt stress increased the malondialdehyde content at 24 h more than salt stress alone. APX activity was not changed under all treatment while CAT enzyme was decreased at 24 h. The proline content was increased only at 96 h under salt stress alone while it did not change under arsenic and salt stress. Nevertheless, the ascorbate content was not changed under all treatments. The ratio of ascorbate/dehydroascorbate was decreased at 24 h but not significiantly at 96 h under salinity. Otherwise it was decreased at 24 h and increased at 96 h under arsenic and salt treatment lead to reduction of the increased MDA content according to 24 h. From these results, it can be suggested that salinity with arsenic stress induced oxidative damage more seriously than salt stress alone with unchanged enzymatic and non enzymatic antioxidants in the leaves of Cakile maritima is a plant succulent halophyte.
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    REGULATION OF AUXIN, ABSCISIC ACID AND SALICYLIC ACID LEVELS BY ASCORBATE APPLICATION UNDER HEAT STRESS IN SENSITIVE AND TOLERANT MAIZE LEAVES
    (Akademiai Kiado Zrt, 2014) Dinler, Burcu Seckin; Demir, Emel; Kompe, Yasemin Ozdener
    In the present study, the effect of ascorbic acid (5 mM) on some physiological parameters and three hormones (auxin, abscisic acid, salicylic acid) was determined under heat stress (40 degrees C) in maize tolerant cv. (MAY 69) and sensitive cv. SHEMAL (SH) at 0 h, 4 h and 8 h. Heat stress reduced total chlorophyll content (CHL), relative water content (RWC) and stomatal conductance (g(s)) in SH but did not lead to changes in MAY 69 at 4 h and 8 h. However, pretreatment with ascorbic acid increased (CHL), (RWC) and (g(s)) in SH under heat stress while it reduced MDA content significantly in both cv. We also observed that heat stress led to a reduction in SA level but increased ABA and IAA levels in SH, whereas it increased SA and IA levels but did not change ABA level in MAY 69 at 4 h. Furthermore, in SH, ASC application under heat stress increased SA level and decreased IAA and ABA levels at 4 h, but it had no effect on SA and ABA at 8 h.