Browsing by Author "Ozfidan-Konakci, Ceyda"

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Citation - Scopus: 2
Melatonin mediated tolerance to benzalkonium chloride phytotoxicity through improved growth- photochemical reactions- and antioxidant system in wild-type and snat2 mutant Arabidopsis lines
(ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2024) Evren Yildiztugay; Busra Arikan Abdulveli; Ceyda Ozfidan-Konakci; Ismail Turkan; Turkan, Ismail; Yildiztugay, Evren; Arikan Abdulveli, Busra; Abdulveli, Busra Arikan; Ozfidan-Konakci, Ceyda
Melatonin (Mel) is a phytohormone that plays a crucial role in various plant processes including stress response. Despite numerous studies on the role of Mel in stress resistance its significance in plants exposed to benzalkonium chloride (BAC) pollution remains unexplored. BAC a common antiseptic poses a threat to terrestrial plants due to its widespread use and inefficient removal leading to elevated concentrations in the environment. This study investigated the impact of BAC (0.5 mg L-1) pollution on wild-type Col-0 and snat2 knockout mutant Arabidopsis lines revealing reduced growth altered water relations and gas exchange parameters. On the other hand exogenous Mel (100 mu M) treatments mitigated BAC-induced phytotoxicity and increased the growth rate by 1.8-fold in Col-0 and 2-fold in snat2 plants. snat2 mutant seedlings had a suppressed carbon assimilation rate (A) under normal conditions but BAC contamination led to further A repression by 71% and 48% in Col-0 and snat2 leaves respectively. However Mel treatment on stressed plants was successful in improving Fv/Fm and increased the total photosynthesis efficiency by regulating photochemical reactions. Excessive H2O2 accumulation in the guard cells of plants exposed to BAC pollution was detected by confocal microscopy. Mel treatments triggered almost all antioxidant enzyme activities (except POX) in both Arabidopsis lines under stress. This enhanced antioxidant activity facilitated by foliar Mel application contributed to the alleviation of oxidative damage regulation of photosynthesis reactions and promotion of plant growth in Arabidopsis. In addition to corroborating results observed in many agricultural plants regarding the development of tolerance to environmental stresses this study provides novel insights into the action mechanisms of Mel under the emerging pollutant benzalkonium chloride.
Role of Sirtuins in Heat Stress Tolerance under Elevated CO2 in Arabidopsis: Photosynthesis, Antioxidant System and Redox Regulation
(Springer, 2026) Alp-Turgut, Fatma Nur; Arikan-Abdulveli, Busra; Turkan, Ismail; Yildiztugay, Evren; Ozfidan-Konakci, Ceyda
Current knowledge about what the protective roles of elevated CO2 concentration (eCO(2)) on chlorophyll fluorescence, PSII photochemistry and antioxidant capacity of Arabidopsis with heat stress remains insufficient. Besides, there is a lack of information on the tolerance mechanism of plants against stress in the presence or absence of sirtuin genes. This study aimed to investigate how eCO(2) (800 ppm) mitigated heat stress (36 degrees C)-dependent oxidative damages through analyzing growth, water content, gas exchange, chlorophyll fluorescence, electron flux efficiency in PSII, antioxidant capacity and lipid peroxidation in Arabidopsis thaliana cv. Columbia-0 (Col-0) and its sirtuin-deficient mutant (srt2) plants. The focus was on investigating the function of the SRT2 gene, particularly in comparison with wild-type plants. Therefore, the sirtuin inhibitor (sirtinol, 1 & micro;M S) was applied to Col-0 plants and the effects of ambient (400 ppm) and eCO(2) heat (H) under stress were also examined. The reductions in growth and water content of heat stress-treated Col-0 and srt2 mutants were eliminated by eCO(2) exposure. The elevated CO2 was removed the reductions on chlorophyll fluorescence, carbon assimilation rate and carboxylation efficiency dependent by H stress in Col-0 plants, but not in srt2 mutants. S supplementation to Col-0 plants produced effects similar to those observed under stress across all measured parameters. While the structural indicators and electron fluxes of PSII and performance indices were disrupted by H stress, eCO(2) provided the positive effects on the photochemistry of PSII in the wild type of Arabidopsis. Interestingly, the eCO(2)-triggered alleviation against stress in srt2 mutants was not maintain. The induced (SOD and GR) and reduced activities (POX, APX, AsA/DHA and GSH redox state) of antioxidant systems point to increased H2O2 accumulation in both Col-0 (123%) and srt2 mutant (40%). Both of the Arabidopsis plants experienced oxidative stress as proved by the high levels of lipid peroxidation. eCO(2) under H stress resulted in remarkable decline in H2O2 accumulation, which contributed to POX and AsA regeneration in Col-0 and POX, AsA and GSH redox status in srt2. Sirtinol application to Col-0 plants also eliminated eCO(2)-mediated protection on TBARS content. This study provides the first evidence of SRT2 involvement in CO2-mediated heat stress tolerance.