Browsing by Author "Cicek, Nuran"

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    Are the Photosynthetic Performance Indexes and the Drought Factor Index Satisfactory Selection Criterion for Stress?
    (2015) Cicek, Nuran; Arslan, Ozlem; Culha-Erdal, Sekure; Eyidogan, Fusun; Ekmekci, Yasemin; ACA-9644-2022
    This study was conducted to assess the drought stress and the recovery responses of twenty one chickpea cultivars (Cicer arietinum L.) grown in Turkey. 20-day-old seedlings were subjected to mild drought conditions for 7 days, recovery period of 3 days followed. Then a moderate stress period of 10 days was applied, followed by recovery period of 4 days. Finally, severe stress period of 13 days was applied, followed by recovery period of 5 days. Drought stress treatments were observed to have an adverse effect on photosynthetic efficiency, but also malondialdehyde, total chlorophyll (app. half of cultivars) and carotenoid contents of leaf tissue have increased when compared with their controls. 21 chickpea cultivars were classified into four groups; highly tolerant, tolerant, less tolerant and sensitive, according to the drought factor index (DFI), the values calculated by photosynthetic performance index (PItotal). Only four cultivars recovered from severe drought stress conditions. Aziziye and Diyar 95 cultivars may be suggested to be cultivated in drought-prone areas. In general, the present results indicate that: 1. PItotal and DFI are very satisfactory selection criterion for drought stress. 2. The recovery processes of plants exposed to environmental constraints should be investigated to make the right selection.
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    Role Of Sulfur Metabolism In Acquiring Of Boron Tolerance In Arabidopsis Thaliana
    (TURKISH JOURNAL OF BOTANY, 2024) Yirmibes, Seda; Kayihan, Ceyhun; Cicek, Nuran; Ekmekci, Yasemin
    The purpose of this study was to assess whether sulfate treatment (pre- and combined) caused changes in the tolerance against boron (B) toxicity in Arabidopsis thaliana at the physiological, biochemical, and molecular levels. Germinated plants were grown in a controlled climate chamber (22 +/- 1 degrees C temperature, 16/8 s photoperiod, 200 mu mol m -2 s -1 light intensity and 50%-60% humidity) for 12 days. The sulfate pretreatment groups (PS-3B and PS-5B) were then transferred to nutrient medium containing Mg2SO4- type sulfate for 3 days. Afterward, they were transferred to petri dishes containing different boron concentrations (3 and 5 mM H3BO3), along with the nonpretreatment and combined (S+3B and S+5B) treatment groups, and exposed to boron toxicity for 10 days. The leaf area, plant biomass, and total chlorophyll content decreased significantly depending on the accumulation of B. Toxic levels of B adversely affected the structure and functionality of the photosynthetic apparatus. Changes were seen in the specific and phenomenological energy fluxes, quantum yields, and efficiency of the photosystem II (PSII) donor and acceptor sides. These changes led to decreases in the photosynthetic performance of the plants. Although B toxicity adversely affected the integrity of the membrane and the amount of photosynthetic pigment in the antenna and reaction centers (RCs), this effect was not at a level that completely blocked the functionality of the photosystems, and this negative effect was alleviated with the sulfate treatment. The increases in the antioxidant enzyme activities (especially peroxidase) and phenolic compounds with the sulfate treatment may have provided tolerance against toxicity and oxidative damage by regulating the defense systems. Moreover, B toxicity affected the relative expression of genes related to sulfate uptake, transport, and sulfur metabolism. In fact, the genes of sulfate transporters ( SULTR ); SULTR3;1, SULTR3;3, and SULTR3;5 were more expressed in PS-B group. The glutamate cysteine ligase (GSH1) and glutathione synthetase 1 (GSH2) relative gene expressions were increased in the treatment groups, indicating induced glutathione metabolism. In conclusion, plants may have acquired tolerance against B toxicity by assimilating sulfate, especially that provided by sulfate pretreatment.