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Öğe Abscisic acid cross-talking with hydrogen peroxide and osmolyte compounds may regulate the leaf rolling mechanism under drought(Springer Heidelberg, 2018) Sezgin, Asiye; Altuntaş, Cansu; Sağlam, Aykut; Terzi, Rabiye; Demiralay, Mehmet; Kadıoğlu, AsımLeaf rolling observed in some crops such as maize, rice, wheat and sorghum is an indicator of decreased water status. Moderate leaf rolling not tightly or early increases the photosynthesis and grain yield of crop cultivars under environmental stresses. Moreover, the effects of exogenous abscisic acid (ABA) on stomatal conductance, water status and synthesis of osmotic compounds are a well-known issue in plants subjected to water deficit. However, it is not clear how the cross-talk of ABA with H2O2 and osmolyte compounds affects the leaf rolling mechanism. Regulation mechanism of leaf rolling by ABA has been first studied in maize seedlings under drought stress induced by polyethylene glycol 6000 (PEG 6000) in this study. ABA treatment under drought stress reduced hydrogen peroxide (H2O2) content and the degree of leaf rolling (%) while the treatment-induced ABA synthesis, osmolyte levels (proline, polyamine and total soluble sugars) and some antioxidant enzyme activities in comparison to the plants that were not treated with ABA. Furthermore, exogenous ABA up-regulated the expression levels of arginine decarboxylase (ADC) and pyrroline-5-carboxylate synthase (P5CS) genes and down-regulated polyamine oxidase (PAO), diamine oxidase (DAO) and proline dehydrogenase (ProDH) gene expressions. When endogenous ABA content was decreased by the treatment of fluoridone (FLU) that is an ABA inhibitor, leaf rolling degree (%), H2O2 content and antioxidant enzyme activities increased, but osmolyte levels, ADC and P5CS gene expressions decreased. Finally, the treatment of ABA to maize seedlings exposed to drought stress resulted in the stimulation of the antioxidant system, osmotic adjustment and reduction of leaf rolling. We concluded that ABA can be a signal compound cross-talking H2O2, proline and polyamines and thus involved in the leaf rolling mechanism by providing osmotic adjustment. The results of this study can be used to provide data for the molecular breeding of maize hybrids with high grain yield by means of moderately rolled leaves.Öğe Application of proline to root medium is more effective for amelioration of photosynthetic damages as compared to foliar spraying or seed soaking in maize seedlings under short-term drought(TUBITAK Scientific & Technical Research Council Turkey, 2017) Demiralay, Mehmet; Altuntaş, Cansu; Sezgin, Asiye; Terzi, Rabiye; Kadıoğlu, AsımExogenous proline (PRO) at low concentrations can enhance drought stress tolerance in different application modes such as application to rooting medium, foliar spray, and seed soaking. However, there is no information about which application mode is more effective for increasing the drought tolerance. Comparative effects of 1, 10, and 20 mM PRO applications through three application modes to hydroponically grown seedlings were examined under short-term drought stress in maize seedlings. Effects on leaf water potential, membrane damage, chlorophyll content, proline level, and gas exchange parameters such as net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (gs), and substomatal CO2 concentration (Ci) were compared. Results indicated that PRO pretreatments raised the water potential, chlorophyll content, Pn, E, gs, and Ci but lowered the malondialdehyde content in the three application modes as compared to the untreated plants. Of the three different modes of PRO pretreatment, rooting medium treatment at 1 mM concentration was also more effective in alleviating stress-induced damages in maize seedlings. Moreover, effectively applied PRO increased the maximum quantum efficiency of PS II, quantum yield of PS II photochemistry, photochemical quenching, and electron transport rate but decreased nonphotochemical quenching of chlorophyll fluorescence under short-term drought stress. In conclusion, exogenous PRO was markedly more effective in the root-treated mode than in foliar spray or seed soaking mode, suggesting that PRO had a different ameliorating effect in different application modes. Proline application in an effective mode can induce photochemical efficiency under short-term drought in maize.Öğe Application of sucrose modulates the expressions of genes involved in proline and polyamine metabolism in maize seedlings exposed to drought(ACAD Sciences Czech Republic, 2019) Altuntaş, Cansu; Sezgin, Asiye; Demiralay, Mehmet; Terzi, Rabiye; Sağlam, Aykut; Kadıoğlu, AsımSucrose, proline, and polyamines are compatible solutes accumulating in plant tissues and increasing cellular osmolarity under environmental stresses. These compatible solutes and hydrogen peroxide can function as signaling molecules in plants. There has been very little evidence how the supply of sucrose changes the biosynthesis of compatible solutes. This study aimed to assess the cross-talk among sucrose, H2O2, and compatible solutes on the expression of genes encoding key enzymes in the pathways of proline and polyamine metabolism in drought stressed maize seedlings. Drought stress (induced by polyethylene glycol solution) increased the expressions of genes encoding pyrroline-5-carboxylate synthetase (P5CS), arginine decarboxylase (ADC), and S-adenosylmethionine decarboxylase (SAMDC), while decreased proline dehydrogenase (ProDH), diamine oxidase (DAO), and polyamine oxidase (PAO) expressions. Addition of sucrose to the stressed seedlings increased the P5CS, ADC and SAMDC expressions more than drought stress alone and reduced more the ProDH, DAO, and PAO expressions. Moreover, exogenous sucrose increased leaf water potential and the content of proline, polyamines, and total soluble sugars, whereas decreased H2O2 content and membrane damages under the drought stress conditions. Consequently, exogenous sucrose contributed to the preservation of water status and the amelioration of damage in maize seedlings under the drought stress.Öğe Artvin ili sınırlarında doğal olarak yetişen Osmanthus decorus (Oleaceae) Kasaplıgil türünün antioksidan özelliklerinin değerlendirilmesi(Artvin Çoruh Üniversitesi, 2024) Avcı, Ömer Faruk; Canbolat, Deniz; Kılıç, Burak; Demiralay, MehmetMevcut çalışmada Artvin ilinde doğal olarak yetişen Osmanthus decorus (Boiss. & Balansa) Kasaplıgil bitkisinden alınan yaprak ve meyve örneklerinin aktarlardan temin edilen kuşburnu (Rosa canina L.) ve ıhlamur (Tilia cordata Mill.) bitkileri ile antioksidan özelliklerinin kıyaslanması amaçlanmıştır. Osmanthus örnekleri (yaprak ve meyveleri) kurutma ve liyofilize olmak üzere iki farklı yöntemle hazırlanmıştır. Kuşburnu ve ıhlamurlar ise kurutulmuş örnek şeklinde aktarlardan temin edilmiştir. Bitki örneklerinde antioksidan kapasiteyi belirlemek için DPPH, FRAP, ABTS testleri, toplam polifenolik bileşik miktarı ve toplam flavonoid analizleri gerçekleştirilmiştir. Bulgular üç türün de antioksidan kapasiteye sahip olduğunu göstermekle birlikte Osmanthus örnekleri toplam flavonoid içeriği hariç kuşburnu ve ıhlamurun gerisinde kalmıştır. Ayrıca örnek hazırlama yönteminin (kurutma ve liyolifizasyon gibi) Osmanthus örneklerinde antioksidan kapasiteyi etkilediği gözlenmiştir. Sonuç olarak, O. decorus bitkisinin hazırlama yöntemlerine göre değişen bir antioksidan etkinliğe sahip olduğu kanaatine varılmıştır.Öğe Artvin-Hatila, Yusufeli, Ardanuç ve Şavşat ilçelerinden temin edilen çiçek balı örneklerinde kalite analizleri(Artvin Çoruh Üniversitesi, 2025) Namlı, Mesut; Ulu Delice, Serap; Kılıç, Burak; Canbolat Gültekin, Deniz; Gümrükçüoğlu, Abidin; Turan, Önder; Demiralay, MehmetBal, bitkilerin nektarından, bitkilerin canlı kısımlarının salgılarından veya bu kısımlar üzerinde beslenen bazı böceklerin salgılarından, bal arıları tarafından toplanarak kendine özgü maddelerle zenginleştirilen, suyu uçurularak olgunlaşması için peteğe bırakılan tatlı bir maddedir. Tüketicilerin güvenle ve kaliteli bal tüketebilmesi için balın ulusal ve uluslararası standartlara uygun olması gerekmektedir. Nem, iletkenlik, pH ve asitlik, prolin değeri, diastaz aktivitesi (sayısı) ve hidroksimetil furfural (HMF) seviyesi bu standartlardan bazılarıdır. Bu çalışmada Artvin’in Hatila, Yusufeli, Şavşat ve Ardanuç ilçelerinden belirlenen istasyonlardan 3 farklı sağım döneminde (2022, 2023 ve 2024 yılları) temin edilen çiçek ballarında uluslararası komisyonlar ve kurumlar tarafından belirlenmiş standart kalite analizleri yapılmıştır. Bulgular Yusufeli İlçesi Dereiçi (Hermut) Köyü balının tüm sağım dönemlerinde diğer istasyonlara göre belirtilen parametreler (özellikle prolin içeriği) açısından genel olarak daha iyi değerler sergilediğini göstermiştir. Ek olarak tüm bal örneklerinin hem Türk Gıda Kodeksi Bal Tebliği hem de IHC (Uluslararası Bal Komisyonu) standartlarına uygun olduğu mevcut çalışma ile tespit edilmiştir.Öğe Combined application of rutin and silicon sustains maize seedlings osmotic stress tolerance by improving photosynthetic capacity and chlorophyll metabolism(Department of Biology, Faculty of Science, University of Zagreb, 2025) Sezgin Muslu, Asiye; Altuntaş, Cansu; Altansambar, Namuun; Demiralay, Mehmet; Kadıoğlu, AsimIn the current study, the role of external applications of rutin (Rut) and silicon (Si) in stress tolerance was investigated. Although it is known that Si has a role in improving plant defense against a variety of stresses, the role of Rut application in stress response remains unclear. Therefore, the current study was designed to evaluate the function of the synergistic effect of combined Rut and Si applications on the photosynthetic capacity of maize seedlings under osmotic stress. Twenty-one-day-old seedlings were treated with Rut (60 mg L⁻¹) and Si (1 mM), and exposed to osmotic stress (induced by 10% and 15% (w/v) polyethylene glycol) for 48 h. The individual application of Rut and Si and especially the simultaneous treatment of Rut+Si improved the gas exchange parameters, chlorophyll content, photosystem II (PSII) activity, Rubisco enzyme activity, and the expression levels of magnesium chelatase and Rubisco genes, but decreased the expression of chlorophyllase gene under osmotic stress in comparison to osmotic stress alone. These findings suggest that exogenous Rut and Si can improve photosynthetic capacity in maize seedlings exposed to osmotic stress by increasing PSII activity and the expression of genes involved in photosynthesis and chlorophyll metabolism, as well as reducing chlorophyll degradation. The simultaneous treatment of Rut+Si may be useful in developing osmotic stress tolerance of plants.Öğe Copper stress and responses in plants(Elsevier Science BV, 2016) Sağlam, Aykut; Yetişsin, Fuat; Demiralay, Mehmet; Terzi, RabiyeNo abstract availableÖğe Exogenous acetone O-(4-chlorophenylsulfonyl) oxime alleviates Cd stress-induced photosynthetic damage and oxidative stress by regulating the antioxidant defense mechanism in Zea mays(Springer, 2022) Demiralay, MehmetCadmium (Cd) toxicity in leaves decreases their photosynthetic efficiency by degrading photosynthetic pigments, reducing the activity of gas exchange parameters and photosystem II (PSII), and producing reactive oxygen species. Although acetone O-(4-chlorophenylsulfonyl) oxime (AO) alleviates stress due to heavy metals in plants, its effects on the photosynthetic apparatus and redox balance under Cd stress are not clear. Herein, the role of AO in modulating the relationship between the antioxidant defense system and photosynthetic performance including chlorophyll fluorescence and gas exchange in mitigating the stress damage caused by Cd in maize seedlings was investigated. Three-week-old maize seedlings were pre-treated with AO (0.66 mM) and exposed to 100 µM Cd stress. Our findings indicated that AO application increased Cd accumulation, thiobarbituric acid-reactive substances (TBARS), photosynthetic rate, hydrogen peroxide (H2O2), total chlorophyll and carotenoid, transpiration, stomatal conductance, maximum photochemical efficiency of PSII (Fv/Fm), effective quantum yield of PSII (?PSII), intercellular CO2 concentration, photochemical quenching (qP), superoxide dismutase, electron transport rate, proline, ascorbate peroxidase, catalase, guaiacol peroxidase, 4-hydroxybenzoic acid, catechol, and cinnamic acid in maize seedling under Cd stress. Conversely, AO significantly reduced oxidative damage levels (H2O2, TBARS). It was concluded that exogenous AO can overcome Cd-mediated oxidative damage and hence protect the photosynthetic machinery by providing stress tolerance and regulating the antioxidant defense mechanism, which includes proline, phenolic compounds, and antioxidant enzyme activitiesÖğe Exogenous alpha lipoic acid can stimulate photosystem II activity and the gene expressions of carbon fixation and chlorophyll metabolism enzymes in maize seedlings under drought(Elsevier GMBH, 2019) Sezgin, Asiye; Altuntaş, Cansu; Demiralay, Mehmet; Cinemre, Salih; Terzi, RabiyeProtective compounds such as non-enzymatic antioxidants, osmolytes and signal molecules have been applied to plants exposed to various environmental stresses to increase their stress tolerance. However, there are not enough records about the response of plants to alpha lipoic acid (ALA) application with antioxidant properties. Therefore, this study was designed to evaluate the function of exogenous ALA on the photosynthetic performance of maize seedlings grown in hydroponic conditions under drought stress. Three weeks old seedlings were treated with or without ALA (12 ?M) and they were subjected to drought stress induced by 10% polyethylene glycol (PEG6000) for 24 h. Chlorophyll content, gas exchange parameters, chlorophyll fluorescence and the expression levels of genes involved in CO2 fixation (ribulose-1,5-bisphosphate carboxylase (rubisco), phosphoenolpyruvate carboxylase (PEPc), Rubisco activase (RCA)) and chlorophyll metabolism (magnesium chelatase (MgCHLI) and chlorophyllase (Chlase)) were determined. The application of ALA increased chlorophyll content and the activity of photosystem II in comparison to the untreated seedlings under drought stress. The relative expression levels of Rubisco, PEPc, RCA and Mg-CHLI significantly increased while the Chlase gene expression decreased in seedlings to which ALA was applied in comparison those to which it was not applied under the stress. These results suggest that exogenous ALA can enhance the photosynthetic performance of maize seedlings exposed to drought by inducing photosystem II activity and the gene expressions of carbon fixation and chlorophyll metabolism enzymes.Öğe Exogenous ascorbic acid mitigates accumulation of abscisic acid, proline and polyamine under osmotic stress in maize leaves(Springer Heidelberg, 2015) Terzi, Rabiye; Kalaycıoğlu, Ebru; Demiralay, Mehmet; Sağlam, Aykut; Kadıoğlu, AsımThe effects of osmotic stress (polyethylene glycol, PEG 6000) and exogenous ascorbic acid (ASC) on abscisic acid (ABA), some osmolytes (proline and polyamine), and gene expression of polyamine metabolic enzymes arginine decarboxylase (ADC), S-adenosylmethionine decarboxylase (SAMDC) and polyamine oxidase (PAO1) were assessed in the leaves of Zea mays L. seedlings. ASC (0.1 mM) was hydroponically applied to detached maize seedlings. ASC application scavenged endogenous hydrogen peroxide level and ameliorated leaf water status and stomatal conductance under osmotic stress. Lipid peroxidation, ABA and osmolyte accumulation were mitigated by ASC treatment. For osmolytes, the alleviation of polyamine accumulation was more obvious than that of the proline. Therefore, gene expressions of polyamine metabolic enzymes were investigated. Compared to control seedlings, down-regulation of SAMDC and ADC gene expressions were determined in ASC ? PEG-applied seedlings while PAO1 gene expression increased. These results indicated that exogenous ASC influenced polyamine metabolism. ASC application under the osmotic stress ameliorated osmotic solute levels and ABA concentration in maize.Öğe Hydrogen peroxide extends postharvest life of Ctenanthe setosa leaf cuts under osmotic stress by reducing leaf rolling(Korean Soc Horticultural Science, 2014) Sağlam, Aykut; Kalaycıoğlu, Ebru; Güven, Funda Gül; Saruhan, Neslihan; Kadıoğlu, Asım; Demiralay, MehmetReducing effects of exogenous hydrogen peroxide on leaf rolling in detached leaves of Ctenanthe setosa were studied. The leaves were kept in H2O2 solutions ranging from 0 to 1 mM for 48 h and then, osmotic stress was applied for 4 h by polyethylene glycol (PEG). Degree of leaf rolling, loss of leaf water, and malondialdehyde (MDA) content were reduced by 0.2 mM H2O2. Antioxidant enzymes were induced by 0.2 mM H2O2. Endogenous H2O2 content was increased after the 0.5 and 1 mM H2O2 treatments but was decreased after 0.2 mM H2O2 treatment. Proline was decreased after exogenous H2O2 applications. Total soluble sugar content was increased as compared to the control after 0.2 mM H2O2 treatment. In conclusion, low-dose exogenous H2O2 treatment could delay leaf rolling by inducing tolerance to osmotic stress due to modulation of the antioxidant system, soluble sugar accumulation, and maintenance of leaf hydration. Therefore, postharvest life of C. setosa cut foliage could be extended by 0.2 mM H2O2 treatments.Öğe İki farklı tip tahribatsız portatif klorofil metre kullanarak Artvin’de yayılış gösteren sapsız meşede (Quercus, Fagaceae) klorofil tahmini(Artvin Çoruh Üniversitesi, 2019) Demiralay, Mehmet; Sadıklar, Murat Sabri; Tilki, FahrettinBu çalışmada, SPAD-502Plus ve CCM-300 adlı optik klorofil içerik ölçer cihazlarından elde edilen klorofil içerik değerleri ile %80 aseton ile klorofil ekstraksiyon metodundan elde edilen klorofil içerik değerleri arasındaki ilişkinin saptanması amaçlanmıştır. Bu çalışma, sapsız meşenin, Quercus petraea (Mattuschka) Liebl. subsp. iberica (Steven ex Bieb.) Krassiln. alt türü üzerinde gerçekleştirilmiştir. Rakımı 889 m olan önceden belirlenmiş bir alandan benzer özelliklere sahip 11 ağaç seçilmiş, sağlıklı toplam 44 yaprak üzerinde ölçümler gerçekleştirilmiştir. Yapraklara ait SPAD, CFR (klorofil floresans) değerleri ve %80 aseton ile klorofil ekstraksiyonu devamında yapılan spektrofotometrik okumalar sonucunda elde edilen bulgular ayrı ayrı değerlendirilmiştir. Ölçümler sonucunda, her üç ölçüm tipi (SPAD, CFR ve %80 aseton metodu) sonuçlarının kuvvetli ilişki sergilediği tespit edilmiştir. Elde edilen SPAD ve CFR değerlerinin %80 aseton ile ekstraksiyon metodundan elde edilen verilere dönüştürülmesi amacıyla regresyon analizleri ile çeşitli eşitlikler oluşturulmuştur. Bu eşitlikler kullanılarak, SPAD ve CFR değerlerinin, kimyasal metodla tespit edilmiş klorofil içerik değerlerine dönüşümü mümkün olabilmektedir. Bu çalışmada, bu meşe türü için, birim alan başına yaprak toplam klorofil konsantrasyonu, SPAD (R2=0.9367) ve CFR (R2=0.8702) okumaları arasındaki ilişkinin, taze ağırlık başına yaprak toplam klorofil konsantrasyonuna göre (SPAD (R2=0.8264) ve CFR (R2=0.7847)) daha yüksek olduğu tespit edilmiştir. Bu sonuçlara göre, bu optik cihazları kullanarak, tercihen birim alan başına (mg cm-2), yaprak toplam klorofil içeriği çok kısa sürede ve kolaylıkla yapraklara zarar vermeden belirlenebilir.Öğe Increased dehydrin level decreases leaf rolling grade by altering the reactive oxygen species homeostasis and abscisic acid content in maize subjected to osmotic stress(Springer Nature, 2022) Saruhan Güler, Neslihan; Terzi, Rabiye; Demiralay, Mehmet; Öztürk, Kamil; Kadıoğlu, AsımAbstract Dehydrins (DHNs) are stress proteins involved in the development of protective reactions in plants against dehydration. The relationship between DHNs and morphological responses such as leaf rolling in plants exposed to water defcit is not well known. In this study, we detected how variations in DHN levels afect the leaf rolling response in maize exposed to osmotic stress in relation to the antioxidant system and ABA level. In this context, we altered the DHN levels in maize seedlings by treatment with bio-regulators (salicylic acid and abscisic acid) under PEG6000-free and PEG6000-induced osmotic stress. When the DHN levels were increased by the bio-regulators (25 µM SA and 100 µM ABA), the relative expression level of the Zea mays dehydrin COR410 gene increased in the seedlings, while reactive oxygen species (ROS) and leaf rolling grade decreased. Moreover, induction of DHNs caused increases in the antioxidant enzyme activity and content of antioxidant substances, and very high amounts of endogenous abscisic acid. When DHN level was suppressed by a bio-regulator (200 µM SA) in the maize seedlings, dehydrin COR410 expression level decreased, while ROS and the leaf rolling grade increased. Moreover, the antioxidant enzyme activity and content of antioxidant substances decreased in the seedlings, while the amount of abscisic acid increased. Taken all together, an increase in DHN level by bio-regulator treatment can stimulate the antioxidant system, enable abscisic acid regulation, and thus reduce leaf rolling through decreased ROS levels. The results also indicated that DHNs may be involved in the signal pathways inducing expression of some genes related to leaf rolling response, possibly by modulating ROS levels, in maize seedlings exposed to osmotic stress.Öğe Investigation of the roles of hydrogen peroxide and NADPH oxidase in the regulation of polyamine metabolism in maize plants under Drought Stress Conditions(Ankara Üniversitesi, 2022) Demiralay, Mehmet; Sağlam, Aykut; Yetişsin, Fuat; Kadıoğlu, AsimThe relationship between hydrogen peroxide and the metabolism of polyamines and the role of NADPH oxidase (NOX) in that relationship under drought conditions remains unclear. To reveal the relationship, expression levels of the genes in polyamine metabolism, such as arginine decarboxylase, agmatine aminohydrolase, spermidine synthase, S-adenosyl methionine decarboxylase, diamine oxidase, and polyamine oxidase were determined by RT PCR under drought stress combined with exogenous hydrogen peroxide (H2O2) and diphenyleneiodonium chloride (DPI) treatments in maize seedlings. In addition, some basic stress parameters (leaf water potential, lipid peroxidation), levels of polyamines (putrescine, spermidine, and spermine), and gene expression of NOX were measured under drought stress. Exogenous H2O2 induced the polyamine content by up-regulating polyamine-synthesizing genes and downregulating polyamine oxidizing genes. When the NOX enzyme was inhibited by DPI, the polyamine pathway tended towards degradation instead of production. Exogenous H2O2 regulated the metabolism of polyamines to promote their synthesis, and NOX played a key role in that regulationÖğe Leaf anatomical notes on Cirsium Miller (Asteraceae, Carduoideae) from Turkey(Springer Wien, 2015) Özcan, Melahat; Demiralay, Mehmet; Kahriman, AydınHere, we describe the leaf anatomical characters of 26 Cirsium taxa (33 accessions) native to the northeast region of Turkey, with the aim of evaluating their taxonomic significance within the taxa. Leaf anatomies of all taxa were characterized and compared using cluster analysis and multidimensional scaling analysis. The transverse sections of the leaves showed various numbers of vascular bundles and accessory bundles. In addition, significant differentiations were observed in the midrib and lamina thickness, the height and width of vascular bundle, and number of stomata, and epidermal cell wall patterns in the abaxial and adaxial surfaces among the taxa. These results demonstrate that the compared anatomical characters among taxa are partly in accordance with their sectional delimitation in the Flora of Turkey. However, our data suggest that some taxonomic re-arrangements might be necessary. Based on its anatomy, we propose that the Cirsium taxa can be treated as pioneers. Some ecological interpretations are also made.Öğe Leaf rolling reduces photosynthetic loss in maize under severe drought(Univ Zagreb, 2014) Sağlam, Aykut; Kadıoğlu, Asım; Demiralay, Mehmet; Terzi, RabiyeEffects of leaf rolling (LR) on maize photosynthesis under severe drought stress were studied in two cultivars with opposite drought responses, Batem 56-55 (drought tolerant) and Batem 51-52 (drought sensitive). Drought stress and artificial prevention of leaf rolling (PLR) were applied at grain filling stage for 30 days. LR in Batem 56-55 occurred later than in Batem 51-52. Leaf water potential (Psi(leaf)) did not change in Batem 56-55 but decreased in Batem 51-52 at LR. Maximum quantum yield of photosystem II (F-v/F-m), effective quantum yield of photosystem II (Phi(PSII)) and electron transport rate (ETR) of the cultivars decreased during LR more significantly in Batem 56-55 in comparison to Batem 51-52. The same was observed for the decrease in net photosynthetic rate (P-N), stomatal conductance (g(s)), transpiration (E) and intracellular level of CO2 (C-1) Rubisco activity and content were reduced at LR, but were less affected in Batem 56-55 than in Batem 51-52. Ear and kernel weights also decreased at LR. All parameters at PLR were more reduced than those of LR. These results implied that LR was an important and necessary mechanism protecting photosynthesis and reducing yield loss under drought stress by maintaining the leaf hydration, preventing loss of the photosynthetic pigments, sustaining the activity of PSII, keeping the stomata open, and conserving the activity of Rubisco.Öğe Naphthalen-1-yl 2,4,6-trimethyl benzenesulfonate enhances cadmium tolerance in Zea mays by boosting antioxidant defense and photosynthetic efficiency(Taylor and Francis Ltd., 2025) Altuntaş, Cansu; Gümrükçüoğlu, Abidin; Yetişsin, Fuat; Demiralay, MehmetCadmium (Cd) contamination in agricultural soils is a serious environmental issue that reduces crop yield and threatens food safety and human health. While conventional chelators enhance Cd uptake, they often impair plant health. This study investigates whether naphthalene-1-yl 2,4,6-trimethyl benzenesulfonate (NTB) acts as a dual-functional agent by enhancing Cd uptake and reducing toxicity in maize. Maize seedlings pretreated with 0.25 mM NTB and exposed to 100 µM CdCl2 showed a 69% increase in Cd accumulation. NTB reduced oxidative stress, lowering TBARS and H2O2 levels by 37% and 34%, respectively. Proline accumulation rose by only 12%, and RWC increased by 9%, indicating improved stress tolerance. Antioxidant enzyme responses shifted: SOD activity declined by 71%, while CAT, APX, and GPX decreased by 24%, 19%, and 37%. NTB also elevated antioxidants, including gallic acid (61%), epicatechin (71%), vanillic acid (42%), and rosmarinic acid (64%). Total chlorophyll increased by 68%, and gas exchange parameters improved: Pn by 70%, Tr by 46%, gs by 14%, and Ci by 72%. Fluorescence parameters also improved, with Fv/Fm and ΦPSII increasing by 19% and 14%, and NPQ decreasing by 14%. These results show that NTB enhances Cd uptake while maintaining physiological balance, offering a promising phytoremediation strategy.Öğe Osmotik Stres Koşullarında Dıştan Uygulanan Osmolitlerin Hücresel Poliamin, Prolin, Sakkaroz ve Absisik Asit Metabolizması İle İlgili Gen İfadeleri Üzerine Etkisi(TUBITAK, 2018) Kadıoğlu, Asım; Sağlam, Aykut; Demiralay, MehmetBitkilerde osmotik stres nedeniyle meydana gelen ürün kayıplarını azaltmak için çeşitli uygulamaların yapıldığı bilinmektedir. Dışarıdan gerçekleştirilen osmolit uygulamaları bu çözümlerden birisidir. Bitkilere dıştan yapılan uygulamalardan en önemlileri prolin, glisinbetain, şeker ve poliamindir. Mevcut projenin amacı, osmotik stres koşulları altında dıştan uygulanan osmolitler (prolin, sakkaroz ve spermidin) ile hücresel osmolitler (prolin, poliamin, şeker) ve ABA metabolizması arasındaki olası etkileşimin hangi genlerle ilişkili olduğu hakkında veriler elde etmektir. Bu amaca ulaşmak için dıştan uygulanan osmolitlerin ve bazı osmolit inhibitörlerinin, prolin, sakkaroz, poliamin ve ABA ile ilgili gen ifadeleri üzerine etkisinin belirlenmesi hedeflenmiştir.Öğe Proline-stimulated signaling primarily targets the chlorophyll degradation pathway and photosynthesis associated processes to cope with short-term water deficit in maize(Springer, 2020) Altuntaş, Cansu; Demiralay, Mehmet; Muslu, Asiye Sezgin; Terzi, RabiyeIncreased photosynthetic efficiencies in genotypes with greater proline level and in crops treated with proline under water deficit have been reported in recent years, but the biochemical and molecular mechanisms of this process are still not known. We examined photosystem II (PSII) activity, photosynthetic enzymes, ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco), phosphoenolpyruvate carboxylase (PEPc), rubisco activase (RCA), and chlorophyll metabolic enzymes, magne-sium chelatase (Mg-CHLI), and chlorophyllase (Chlase), which would be the primary targets of exogenous proline to provide photosynthetic protection to plants under PEG-induced short-term water deficit. Two maize genotypes W23/M14 with greater proline content and Şafak with low proline content were hydroponically grown for 21–23 days, and then the seedlings were subjected to water deficit (? 0.75 MPa) induced by PEG6000 for 0, 4, and 8 h. Before the seedlings were exposed to the water deficit, proline (1 mM) was applied to the rooting medium of the Şafak genotype for 2 days. The time course effects of the applications showed that exogenous proline significantly enhanced PSII efficiency, PEPc activity, rubisco activity, and the relative expression levels of PEPc, rubisco large subunit, rubisco small subunit, and RCA genes at 0, 4, and 8 h. The W23/M14 genotype had higher rubisco quantity than the Şafak genotype at all time periods. Proline pre-treatment under the stress-free and PEG conditions reduced the activity of Chlase and the gene expressions of Chlase, while it enhanced Mg-CHLIgene expression at 0, 4, and 8 h. Taken together, the results indicated that the primary target of proline-stimulated signaling in maize seedlings exposed to short-term severe water deficit may be to induce PSII efficiency, activities of carbon dioxide fixation enzymes and chlorophyll metabolism and mitigate chlorophyll degradation.Öğe Pseudomonas putida KT2440 induces drought tolerance during fruit ripening in tomato(Universidad Centroccidental Lisandro Alvarado (UCLA), 2022) Sağlam, Aykut; Demiralay, Mehmet; Çolak, Dilsat Nigar; Gedik, Necla Pehlivan; Başok, Oğuz; Kadioğlu, AsımThe current study investigated the effects of Pseudomonas putida strain KT2440 on the drought tolerance of tomato plants during fruit maturation. Plants at the ripening stage of the mature-green were not watered for 20 days to promote drought stress. Concentrations of photosynthetic pigments were determined. Bacteria-soaked tomato plants (BSS) had higher levels of chlorophyll and carotenoids than non-soaked plants (DWS) under stress conditions. Compared to the DWS, stomatal conductance, lipid peroxidation, and hydrogen peroxide content in the BSS plants decreased under drought stress. The ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD) activities increased in BSS plants compared to DWS under drought stress. Furthermore, the number and weight of fruits in both DWS and BSS plants was reduced by the stress, but the reduction in BSS plants was lower than in DWS plants. These results showed that bacteria treatment conferred tolerance to drought stress in tomato plants by reducing the peroxidation extent of polar lipids (PLs), increasing photosynthetic pigment content, and activities of the antioxidant enzymes in the leaves. Therefore, P. putida KT2440 has supported high fruit yield under drought stress as a biotic tolerance elicitor for this plant stress.
