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  • Küçük Resim
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    Effects of high temperature stress on enzymatic and nonenzymatic antioxidants and proteins in strawberry plants
    (Tubitak Scientific & Technical Research Council Turkey, 2016) Gülen, Hatice; Kesici, Müge; Turhan, Ece; İpek, Ahmet; Köksal, Nezihe; Ergin, Sergül
    The mechanism of tolerance to high temperatures was investigated in two strawberry (Fragaria x ananassa Duch) cultivars, 'Redlands Hope' ('R. Hope', heat tolerant) and 'Cal. Giant 3' ('CG3', heat sensitive). Leaves were collected from plants that were exposed to gradual heat stress and heat-shock stress separately. The contents of nonenzymatic antioxidants such as ascorbic acid (AsA) and glutathione (GSH) and the activities of enzymatic antioxidants such as ascorbate peroxidase (APX) (EC 1.11.1.11), catalase (CAT) (EC 1.11.1.6), and glutathione reductase (GR) (EC. 1.6.4.2) were measured followed by heat treatments. Additionally, proline content was determined, and heat shock proteins (HSPs) were analyzed with an immunoblotting method to investigate protein markers involved in the heat-stress tolerance of strawberry plants. The contents of AsA and GSH did not change depending on heat stress type, temperatures, or cultivars. While APX and CAT activities increased with high temperatures, GR activity was almost unchanged. The proline content of the cultivars increased in both treatments. Anti-HSP60 immunoblots revealed that a 23 kDa polypeptide was detected during the heat acclimation of strawberry cultivars. The intensity of the heat shock protein in 'R. Hope' plants was more than in 'CG3' plants. Thus, the accumulation of 23 kDa heat shock protein was correlated with the heat tolerance of the cultivars. In conclusion, strawberry leaf tissues of 'R. Hope' were found to enhance the structural stability of cellular membranes under high temperature by increasing both the activity of such enzymes as CAT and APX to activate the antioxidative systems and the expression of 23 kDa HSP.
  • Küçük Resim
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    Proline and Antioxidant Enzyme Activities in Some Strawberry Cultivars under Drought and Recovery
    (UNIV AGR SCI & VETERINARY MED CLUJ-NAPOCA, 2018) Gülen, Hatice; Kesici, Müge; Çetinkaya, Cem; Ergin, Sergül
    This study examines the molecular effects of drought and recovery applications on four strawberry (Fragaria x ananassa Duch) cultivars known as relatively heat-tolerant ['Redlands Hope' ('R. Hope') and 'Camarosa'] and heat-sensitive ['Festival' and 'Cal. Giant-3' ('CG-3')]. After frigo seedlings were grown in a greenhouse for eight weeks (until they had five-six leaves) in a pot, 10% Poliethyleneglycol 6000 (PEG) was applied in order to compose drought condition for 15 days. Following PEG application, plants were watered without PEG for 15 days to observe the recovery. Leaf relative water content (RWC), loss of turgidity, cell membrane injury, proline content and the activities of ascorbate peroxidase (APX, EC 1.1.11.1), glutathione reductase (GR, EC 1.6.4.2) and peroxidase (PRX, EC 1.11.1.7) were determined in leaf tissues taken from plants at the end of the drought and recovery applications. Although membrane injury was increased by the PEG application, it reduced almost to the control levels at the end of the recovery period. Proline contents were found higher in cvs. 'R. Hope' and 'Camarosa' than cvs. 'Festival' and 'CG-3' under drought conditions. APX and GR enzymes showed great activities in drought applied plants of heat-tolerant cultivars. Native polyacrylamide gel electrophoresis (PAGE) of basic PRX isozymes yielded three protein bands with Rf = 0.45, Rf = 0.55 and Rf = 0.60 that were sharply increased their activities by PEG and recovery applications in cvs. 'R. Hope' and 'Camarosa'. In addition, leaves of all cultivars exposed to drought rolled up and had brown colour in various level as an indication of tolerance. Indeed 'Camarosa' and 'R. Hope' showed better recovery performance after rewatering than 'Festival' and 'CG-3'. All data indicated that heat-tolerant cultivars showed relatively drought tolerance in this study.