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Öğe Activation of Photorespiration Facilitates Drought Stress Tolerance in Lotus corniculatus(Springer, 2022) Unlusoy, Aybuke Guler; Yolcu, Seher; Bor, Melike; Ozdemir, Filiz; Turkan, IsmailPhotorespiration is the process that recycles 2-phosphoglycolate back to 3-phosphoglycerate resulting from the oxygenase activity of Rubisco. Recent studies proved the importance of photorespiration for plant survival under stress conditions, including drought stress. In the present study, physiological, biochemical and molecular responses of a moderately drought-tolerant plant Lotus corniculatus to PEG-mediated drought stress were examined. Growth, stomatal conductance (g(s)), maximum quantum yield of photosystem II (Fv/Fm), CO2 assimilation (A), electron transport (ETR) and transpiration rates (E) were decreased, whilst intercellular CO2 concentrations (Ci), non-photochemical quenching (NPQ) and photorespiration rates were increased in the drought stress-exposed plants. Activities and expression profiles of photorespiratory cycle enzymes correlated well with the increased photorespiration rates. In the line of our results, we conclude that the activation of photorespiration for recycling 2-phosphoglycolate (2PG) to chloroplast facilitated the maintenance of growth and drought stress tolerance in L. corniculatus. Accordingly, we can speculate that drought stress exerted by PEG20 (20% PEG6000) with an osmotic pressure of -0.73 MPa may be a threshold level for drought tolerance in L. corniculatus since the long-term effects of PEG20 on tolerance-related parameters (RGR, membrane integrity, leaf water status and photosynthesis) were more remarkable.Öğe Ağır metal stresi ile gamma-amino bütirik asit (GABA) etkileşiminin incelenmesi(Ege Üniversitesi, 2014) Akcan Daş, Zeycan; Bor, MelikeAğır metaller, bitkilerde enzimlerin inaktive olmasıyla hücresel/moleküler seviyede pek çok fizyolojik süreci hasara uğratarak fitotoksisiteye neden olmaktadır (Pagliano et al., 2006). ?-Aminobütirik asit (GABA), bakteriler, bitkiler ve omurgalılarda bulunan dört korbonlu proteinik yapıda olmayan bir amino asittir (Steward et al., 1949). Bitkilerde, GABA için sinyalizasyon, böceklere karşı savunma, hücrelere öncülük etme gibi birden fazla roller önerilmiştir (Kinnersley ve Turano, 2000; Bouche et al., 2003). Çeşitli araştırmalarda, abiyotik stres koşullarında GABA seviyesindeki değişimler incelenmiştir (Kinnersley and Trurano, 2000) fakat ağır metal stresi koşullarındaki GABA düzeyleri ve değişimlerini içeren çalışmalar fazla bulunmamaktadır. Bu çalışmada Tütün (Nicotiana tabacum) bitkisinde ağır metal stresi ile GABA metabolizması ilişkisinin belirlenmesi hedeflenmiştir. Bu amaçla, tütün bitkileri farklı konsantrasyonlarda çinko sülfat (ZnSO4) ile indüklenen ağır metal stres koşullarında, GABA ve Glutamat miktarındaki değişimler, Glutamat Dekarboksilaz (GAD) ve Glutamat Dehidrogenaz (GDH) enzimlerindeki aktivite değişimleri ve çeşitli fizyolojik parametreler incelendi. GABA, Glutamat miktarları ve enzim aktiviteleri stres gruplarında farklı düzeylerde belirlendi. Tütün bitkisinde, ZnSO4 ile indüklenen abiyotik stresin GABA metabolizmasını ve bitkilerin strese alışma süreçlerini etkilediği saptandı.;GABA, Nicotiana tabacum, Abiotic Stress, Heavy Metal Stress.;GABA, Nicotiana Tabacum, Abiyotik Stres, Ağır Metal Stresi.Öğe Arabidopsis NATA1 Acetylates Putrescine and Decreases Defense-Related Hydrogen Peroxide Accumulation(Amer Soc Plant Biologists, 2016) Lou, Yann-Ru; Bor, Melike; Yan, Jian; Preuss, Aileen S.; Jander, GeorgBiosynthesis of the polyamines putrescine, spermidine, and spermine is induced in response to pathogen infection of plants. Putrescine, which is produced from Arg, serves as a metabolic precursor for longer polyamines, including spermidine and spermine. Polyamine acetylation, which has important regulatory functions in mammalian cells, has been observed in several plant species. Here we show that Arabidopsis (Arabidopsis thaliana) N-ACETYLTRANSFERASE ACTIVITY1 (NATA1) catalyzes acetylation of putrescine to N-acetylputrescine and thereby competes with spermidine synthase for a common substrate. NATA1 expression is strongly induced by the plant defense signaling molecule jasmonic acid and coronatine, an effector molecule produced by DC3000, a Pseudomonas syringae strain that initiates a virulent infection in Arabidopsis ecotype Columbia-0. DC3000 growth is reduced in nata1 mutant Arabidopsis, suggesting a role for NATA1-mediated putrescine acetylation in suppressing antimicrobial defenses. During infection by P. syringae and other plant pathogens, polyamine oxidases use spermidine and spermine as substrates for the production of defense-related H2O2. Compared to wild-type Columbia-0 Arabidopsis, the response of nata1mutants to P. syringae infection includes reduced accumulation of acetylputrescine, greater abundance of nonacetylated polyamines, elevated H2O2 production by polyamine oxidases, and higher expression of genes related to pathogen defense. Together, these results are consistent with a model whereby P. syringae growth is improved in a targeted manner through coronatine-induced putrescine acetylation by NATA1.Öğe Bitkilerde kök senesensinde antioksidan savunma sisteminin rolünün incelenmesi(Ege Üniversitesi, 2012) Yücel, Çağdaş Kera; Bor, MelikeBitkilerde senesens, yaslanmayla iliskili oldugu kadar mevsimsel degisimin de içinde bulundugu çevresel etkenler tarafından da uyarılmaktadır. Günlerin kısalması ve havaların sogumasıyla bu dogal süreç baslamaktadır. Senesens esnasında metabolizma ve gen ifadelerinde gözlenebilir degisiklikler olmaktadır. Senesens süreci yaprak ve toprak üstü organlarda daha iyi bilinmesine ragmen köklerde bu sürecin nasıl isledigi bilinmemektedir. Mevsimsel degisime baglı senesens sürecinde oksidatif stres ve antioksidan enzimlerin önemli bir role sahip oldugu düsünülmektedir. Çalısmamızda kök yasam döngüleri farklı olan Sparganium androcladum (Engelmann) Morong, Rhynchospora alba (L.) Vahl, Scirpus microcarpus J. Presl ve Carex exilis Dewey gibi çok yıllık sulak alan bitkilerinden ilkbahar, yaz ve sonbahar mevsimlerinde örnekleme yapıldı. Örneklerde, peroksidaz (POX), askorbat peroksidaz (APX), katalaz (CAT) ve glutasyon redüktaz (GR) enzimlerinin aktiviteleri, lipid peroksidasyon düzeyleri ve köklerin canlılık yüzdeleri incelendi. Genel olarak, POX, APX, CAT ve GR aktiviteleri ve lipid peroksidasyonu degerleri S. androcladum ve R. alba ile S. microcarpus ve C. exilis'te benzer düzeylerde degisim gösterdi. lk grubun kök sistemleri sonbaharda canlılıgını yitirken, ikinci gruptaki türlerde kök sistemleri kıs aylarında da canlı kalabilmektedir. Senesens sürecinin incelenmesinde ve ayırd edilmesinde antioksidan enzim degerlerinin belirleyici olabilecegi düsünülmektedir.;Senescence, seasonal changes, antioxidative enzymes, lipid peroxidation.;Senesens, mevsimsel degisim, antioksidan enzim sistemleri, lipid peroksidayonu.Öğe Brassica napus bitkisinde tuz stresi koşullarında Warburg etkisinin incelenmesi(Ege Üniversitesi, 2023) Bor, Melike; Öztürk, Tülay[Öz Yok]Öğe Brassica napus bitkisinin büyüme ve gelişim süreçleri üzerinde glikosinolat hidroliz ürünlerinin etkilerinin incelenmesi(Ege Üniversitesi, 2019) Bor, Melike; Sevim, GülçinBitkiler yaşam döngüleri boyunca farklı çevresel stres etmenlerine maruz kaldıkları için evrimsel süreçte çok çeşitli savunma sistemleri geliştirmişlerdir. Brassicacecae familyasına özgü glikosinolat mirosinaz savunma sistemi de bu spesifik sistemlerden biridir. Glikosinolatlar ve mirosinaz enziminin etkileşimi sonucu oluşan parçalanma ürünleri temelde böcek zararı, mikrobiyal zarar ve yaralanma gibi durumlar için geliştirilmiş olsada sıcaklık, kuraklık, tuzluluk gibi abiyotik streslere karşı da rollerinin olduğu yapılan çalışmalarla ortaya konmuştur. Bununla birlikte, fotosentetik verim, bitki büyümesi ve gelişimi ile glikosinolat savunma sitemi arasında bir etkileşim saptanmıştır. Özellikle kök gelişimi ve glikosinolat yolağı arasında sıkı bir ilişki tespit edilmiş olup, ilgili mekanizma halen aydınlatılmamıştır. Çalışmamızda ticari ve tarımsal öneme sahip Brassica napus bitkisinde dışarıdan uygulanan glikosinolat parçalanma ürünleri allil ve benzil izotiyosiyanatların çeşitli fizyolojik ve biyokimyasal süreçler üzerindeki etkilerini incelemeyi hedefledik. Çalışmamızdan elde ettiğimiz sonuçlar allil ve benzil izotiyosyanat uygulamasının başta fotosentez olmak üzere, kök gelişimi gibi önemli fizyolojik süreçleri etkilediğini göstermektedir. Fotosistem II nin maksimum kuantum verimi, primer kök uzunluğu ve hipokotil uzunluğu azalırken, kök tüyü yoğunluğunda artış gözlenmiştir.; Kök gelişimi, Brassica napus, izotiyosiyanat, glikosinolat.;Root development, Brassica napus, isothiocyanate, glucosinolate.Öğe Brassica napus L. bitkisinde efektör tarafından uyarılan bağışıklığın GABA yolu üzerindeki etkisi(Ege Üniversitesi, 2023) Bor, Melike; Palabıyık, ŞerifeTüm canlılar, devamlı olarak birbirleriyle ve çevresi ile etkileşim halindedir. Sabit yapıları nedeniyle bitkiler, zorlu ve zararlı ortam koşullarından kaçamazlar bu nedenle çeşitli stres etkenleriyle baş etmek zorunda kalırlar. Gamma aminobütirik asit (GABA), dört karbonlu, protein yapısına katılmayan bir aminoasittir. Bitkiler, hayvanlar, bakteriler ve mantarlar dahil olmak üzere tüm canlılarda bulunur. GABA biyosentezi ve katabolizması, glutamat dekarboksilaz (GAD), GABA transaminaz (GABA-T) ve suksinit semialdehit dehidrogenaz (SSADH) enzim aktivitelerini içeren GABA yolu olarak tanımlanan bir süreçtir. GABA ve GABA-yolu bitkilerde hem stres yanıtları hem de normal büyüme ve gelişme süreçlerinde görevleridir. Projemiz kapsamında, bitkilerde GABA yolunun, efektör ile tetiklenen bağışıklık ile nasıl etkileşime girdiğini incelemeyi hedefledik. Bu hedefe ulaşmak için Brassica napus L. bitkisine efektör olarak Flg-22 uyguladık ve uygulama sonrasında yaprak ve kök örneklerinde GABA miktarındaki, fizyolojik parametreler, GDH, GAD, GABA-T ve SSADH enzim aktivitelerindeki, çeşitli stres yanıtları ile ilişkili MYC2, MPK6 ve ZAT12 transkript miktarındaki değişimi inceledik.Öğe Brassinosteroid uygulamasının tuz stresi altında yetiştirilen pirinç bitkisinin fizyolojik ve biyokimyasal özellikleri üzerindeki etkilerinin araştırılması(Ege Üniversitesi, 2007) Türkan, İsmail; Bor, Melike; Demiral, Tijen; Özdemir, FilizTuza duyarli IR-28 pirinç çesidinde tuz stresi kosullarinda 24-epibrassinolid uygulamasinin fide gelisimi, antioksidan enzim aktiviteleri, lipid peroksidasyonu, prolin ve çözünebilir protein miktari üzerine etkileri incelenmistir. Tuz stresi kosullarinda, 24-epiBL uygulamasi sonucunda fide gelisimi olumlu etkilenmistir. 24-epiBL uygulanan gruplar tuz stresine (120 mM NaCl) maruz birakildiklarinda süperoksit dismutaz, katalaz ve glutatyon redüktaz enzim aktivitelerinde önemli bir degisim görülmezken askorbat peroksidaz enziminin aktivitesi belirgin bir artis gösterdi. Peroksidaz enziminin aktivitesi NaCl uygulanan grupta artis gösterirken 24-epiBL + NaCl uygulanan grupta belirgin bir azalma gözlendi. 24-epiBL + NaCl uygulanan grupta lipid peroksidasyonu ve prolin düzeyi azalirken, çözünen protein miktari artis gösterdi.Öğe Capparis bitkisinde Mirosinaz Glikosinolat sisteminin moleküler düzeyde incelenmesi(Ege Üniversitesi, 2009) Özdemir, Filiz; Bor, Melike; Özkur, ÖzdenCapparis spinosa, Capparis ovata, Desülfatlanmıs glikosinolatlar, ntakt glikosinolatlar, Doku kültürü, HPLC.;Capparis spinosa, Capparis ovata, Desulphoglucosinolates, Intact Glucosinolates Tissue culture, HPLC.;Projemizde, Türkiye'de dogal olarak bulunan Capparis spinosa ve Capparis ovata bitkilerindeki "Mirosinaz-Glikosinolat Sistemi" nin incelenmesi amaçlandı. Birçok biyolojik aktiviteyi etkileyen mirosinaz-glikosinolat sistemi çok sayıda bitkide, mantarda ve herbivor böcekte bulunmaktadır. Ancak dogal yayılıs gösteren bitkilerde mirosinaz-glikosinolat sistemi bilesenleri hakkında çok çalısma bulunmamaktadır. Arastırmalarımız kapsamında Capparis bitkilerinin doku kültürü teknigi ile steril kosullarda yetistirilmesi, yaprak, tohum, gövde, tomurcuk ve çiçeklerden ekstrakte edilen örneklerde dogal (intakt) ve desülfatlanmıs glikosinolat miktarlarının belirlenmesine ait analizler yapıldı. Ayrıca sistemin önemli bilesenlerinden mirosinaz enziminin yaprak, tohum, gövde, tomurcuk ve çiçeklerden ekstrakte edilen örneklerdeki çesitli biyokimyasal özellikleri de incelendi. Capparis ovata ve Capparis spinosa yaprak, tohum, gövde, tomurcuk ve çiçeklerinde glikosinolat içerigi ve mirosinaz aktivitesi açısından önemli farklılıklar saptandı. HPLC analizleri sonucunda dogal (intakt) glikosinolatlardan, Glikokapparin, Glikoiberin, Progoitrin, Sinigrin, Glikoeurisin, Glikosinalbin olmak üzere altı farklı glikosinolat belirlendi. Capparis ovata ve Capparis spinosa bitkilerinin yaprak, tohum, çiçek, tomurcuk ve gövde örneklerinden elde edilen desülfatlanmıs glikosinolatlar ise, basta Glikokapparin olmak üzere, Glikoiberin, Progoitrin, Epiprogoitrin, Sinigrin, Glikonapin, Glikosinalbin, Glikobrassisin olarak tespit edildi. Mirosinaz total enzim aktivitesi her iki bitkide de sırasıyla en fazla tohum ve yaprak örneklerinde gözlendi. Capparis mirosinaz enzimi SDS-PAGE analizlerinde moleküler agırlıgı yaklasık 65 kDa olan tek bir bant verdi ve western blot analizleri sonucunda da 3D7 antikoru ile membranda tek bir sinyal gözlendi. Mirosinaz enziminin native (aktif) jel analizleri sonucunda tohum, yaprak ve çiçek dokularında iki belirgin izozim gözlendi. Arabidopsis thaliana TGG1 geninin Northern blot analizleri sonucunda bu genin tohum, yaprak, çiçek ve tomurcuk dokularında ifade oldugu gözlendi.Öğe Combined effects of salt stress and cucurbit downy mildew (Pseudoperospora cubensis Berk. and Curt. Rostov.) infection on growth, physiological traits and antioxidant activity in cucumber (Cucumis sativus L.) seedlings(Academic Press Ltd- Elsevier Science Ltd, 2013) Nostar, Ozge; Ozdemir, Filiz; Bor, Melike; Turkan, Ismail; Tosun, NecipAbiotic and biotic stresses both decrease quality and quantity of cultivated plants. We compared responses of Cucumis sativus L. cvs Sardes and Beith alpha which were treated with 50 or 100 mM NaCl and/or infected by Pseudoperospora cubensis Berk. and Curt. Rostov.. Both cultivars were affected remarkably when fungus infection was combined with salt stress however; cv Sardes was found out to be relatively tolerant with sustainable growth performance, better leaf water status and lower lipid peroxidation levels under this condition. This relative tolerance could be related to the fine tuning of the activities of the antioxidative enzymes and proline levels. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Comparative effects of drought, salt, heavy metal and heat stresses on gamma-aminobutryric acid levels of sesame (Sesamum indicum L.)(Springer Heidelberg, 2009) Bor, Melike; Seckin, B.; Ozgur, R.; Yilmaz, O.; Ozdemir, F.; Turkan, I.Gamma-aminobutryric acid (GABA) accumulation in response to diverse stresses is well known in plants; however, the comparative effects of different environmental stresses on GABA accumulation was not addressed in the same plant system. Here, we investigated GABA accumulation comparatively in sesame (Sesamum indicum L. cv. Cumhuriyet) plant under drought, salt, heavy metal (Se) and high-temperature stresses. Plants were stressed by application of 5% PEG-6000, 150 mM NaCl, 100 mu g g(-1) Se and high temperature (50A degrees C for 2 h). Root and shoot growth reduced after PEG, NaCl, Se and high-temperature treatments. Among these, heavy metal treatment had the highest and earliest effect on growth. GABA accumulation could be related to stress perception rather than protection in sesame plant if we consider that the adverse effects of different abiotic stresses on growth were not elevated by GABA.Öğe Contribution of Gamma amino butyric acid (GABA) to salt stress responses of Nicotiana sylvestris CMSII mutant and wild type plants(Elsevier Gmbh, 2012) Akcay, Nese; Bor, Melike; Karabudak, Tugba; Ozdemir, Filiz; Turkan, IsmailPlants accumulate high levels of Gamma amino butyric acid (GABA) in response to different environmental stresses and GABA metabolism has different functions such as osmotic and pH regulation, bypass of tricarboxylic acid cycle, and C:N balance. The cytoplasmic male sterile (CMS) II mutant of Nicotiana sylvestris has a deletion in the mitochondrial gene nad7 which encodes the NAD7 subunit of complex I which causes increased leaf respiration, impaired photosynthesis, slower growth and increased amino acid levels. In this study we aimed to elucidate the role of GABA and GABA metabolism in different genotypes of the same plant system under salt stress (100 mM NaCl) in short (24h) and long (7, 14 and 21 days) terms. We have investigated the differences in leaf fresh and dry weights, relative water content, photosynthetic efficiency (F-v/F-m), glutamate dehydrogenase (GDH. EC 1.4.1.4) and glutamate decarboxylase (GAD, EC 4.1.1.15) enzyme activities, GABA content and GAD gene expression profiles. GDH activity showed variations in CMSII and wild type (WT) plants in the first 24 h. GAD gene expression profiles were in good agreement with the GAD enzyme activity levels in CMSII and WT plants after 24 h. In long-term salinity, GAD activities increased in \NT but, decreased in CMSII. GABA accumulation in WT and CMSII plants in short and long term was induced by salt stress. Variations in GDH and GAD activities in relation to GABA levels were discussed and GABA metabolism has been proposed to be involved in better performance of CMSII plants under long term salinity. (C) 2011 Elsevier GmbH. All rights reserved.Öğe Day and Night Fluctuations in GABA Biosynthesis Contribute to Drought Responses in Nicotiana tabacum L(Taylor & Francis Inc, 2021) Pelvan, Alpay; Bor, Melike; Yolcu, Seher; Ozdemir, Filiz; Turkan, IsmailWhen synchronized with the light/dark cycle the circadian rhythm is termed a diurnal rhythm and this organizes an organism's daily life cycle in relation to the metabolic shifts during the day/night cycles. This is a complex task, particularly under stress conditions. Accurate maintenance of the diurnal rhythm becomes an issue under environmental extremes, such as drought due to the impairment of metabolism, redox balance, and structural integrity. In plants, the non-proteinogenic amino acid GABA accumulates to high levels in response to several stress factors but this is not always dependent on the activation of its biosynthesis. Here we propose a regulatory role to GABA during the diurnal rhythm in plants which is similar to its function in animals where it adjusts the circadian rhythm. Here we investigated whether GABA-biosynthesis was affected by drought stress during the diurnal cycle. For this, we took samples from leaves of N. tabacum plants subjected to PEG-mediated drought stress (-0.73 MPa) during the day and night cycle during a 24 hour period. Glutamate, GABA, and proline contents, along with GDH, GAD enzyme activities and transcript profiles were analyzed. Overall, we conclude that the oscillations in GABA biosynthesis during day and night cycle have an impact on drought stress responses which needs to be elucidated by further analysis.Öğe The effect of salt stress on lipid peroxidation, antioxidative enzymes and proline content of sesame cultivars(Pergamon-Elsevier Science Ltd, 2007) Koca, Hulusi; Bor, Melike; Ozdemir, Filiz; Turkan, IsmailThe effect of increasing NaCl concentrations was studied on two different cultivars (cv. Orhangazi and cv. Cumhuriyet) of Sesamum indicum. Seedlings were grown for 40 days in half strength Hoagland solution and after 40 days treated with different NaCl concentrations (0, 50 and 100 mM) for 21 days. Differences in growth parameters, lipid peroxidation, antioxidative enzyme activities and proline accumulation were tested in order to put forward the relative tolerance or sensitivity of the cultivars. Results indicated that both parameters differ according to the cultivar's ability in coping oxidative stress caused by salinity. Constitutive levels of antioxidative enzyme activities were almost the same between the cultivars; however, cv. Cumhuriyet was able to induce antioxidative enzyme activities more efficiently when subjected to salt stress. Growth parameters, lipid peroxidation and proline accumulation results are also in good correlation with supporting this cultivar's being relatively tolerant. (C) 2007 Elsevier B.V. All rights reserved.Öğe Histone acetylation influences the transcriptional activation of POX in Beta vulgaris L. and Beta maritima L. under salt stress(Elsevier France-Editions Scientifiques Medicales Elsevier, 2016) Yolcu, Seher; Ozdemir, Filiz; Guler, Aybuke; Bor, MelikeAcetylation of histone proteins is a type of chromatin modification which facilitates the activation of genes. Recent studies brought up the importance of this reversible and rapid process for the regulation of gene expression especially in plant defense against a variety of environmental stresses. Deciphering the exact mechanisms of chromatin modifications under abiotic stress conditions is important for improving crop plants' performance and yield. In a previous study we compared the salt stress responses of Beta vulgaris (sugar beet) and Beta maritima (wild beet). In accordance with those results we suggested that chromatin remodeling can be an active process in the regulation of genes related to salt stress tolerance of these plants. Therefore we performed ChIP assay in control and salt stressed (250 and 500 mM NaCl) plants and compared the enrichment of acetylation in the associated chromatin sites. We found that the transcriptional activation of one peroxidase (PDX) encoding gene was associated with the elevated levels of acetylation in H3K9 and H3K27 sites. The acetylation patterns were remarkably different between two species in which the highest acetylation levels were found at H3K9 and H3K27 in wild beet and sugar beet respectively. (C) 2016 Elsevier Masson SAS. All rights reserved.Öğe Identification and Characterization of the Glucosinolate-Myrosinase System in Caper (Capparis ovata Desf.)(Springer, 2009) Bor, Melike; Ozkur, Ozden; Ozdemir, Filiz; Turkan, IsmailMyrosinase (EC 3.2.1.147) catalyzes cleavage of glucosinolates, which consist of a thioglucoside moiety linked to amino acid-derived side chains. Myrosinase activity and expression profiles were investigated together with glucosinolate contents in Capparis ovata (caper) in order to characterize the glucosinolate-myrosinase system. The desulfoglucosinolates-glucocapparin, glucoiberin, progoitrin, epiprogoitrin, sinigrin, gluconapin, glucosinalbin, and glucobrassicin-were extracted and quantified from leaves, seeds, flowers, flower buds, and young shoots. The major desulfoglucosinolate was glucocapparin, which accumulated to values of 39.35 +/- 0.09 and 25.56 +/- 0.11 mu mol g(-1) dry weight in seed and leaf extracts, respectively. Myrosinase has high activity in caper seeds, leaves, flowers, and flower bud tissues having the highest total activities in seed extracts (79.23 +/- 0.18 U). However, specific activities were the highest in flower bud extracts (200.44 +/- 0.09 U mg(-1) protein). The myrosinase protein migrated as a single band with a molecular weight of 65 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis and on Western blots probed with the myrosinase-specific 3D7 antibodies. Native gel electrophoresis revealed two putative myrosinase isoenzymes in seeds, leaves, and flower tissues. The caper homolog of the Arabidopsis thaliana TGG1 gene was differentially expressed in seeds, leaves, flowers, and flower buds with the highest expression levels in leaves and flower bud tissues.Öğe Identification and Characterization of the Glucosinolate-Myrosinase System in Caper (Capparis ovata Desf.)(Springer, 2009) Bor, Melike; Ozkur, Ozden; Ozdemir, Filiz; Turkan, IsmailMyrosinase (EC 3.2.1.147) catalyzes cleavage of glucosinolates, which consist of a thioglucoside moiety linked to amino acid-derived side chains. Myrosinase activity and expression profiles were investigated together with glucosinolate contents in Capparis ovata (caper) in order to characterize the glucosinolate-myrosinase system. The desulfoglucosinolates-glucocapparin, glucoiberin, progoitrin, epiprogoitrin, sinigrin, gluconapin, glucosinalbin, and glucobrassicin-were extracted and quantified from leaves, seeds, flowers, flower buds, and young shoots. The major desulfoglucosinolate was glucocapparin, which accumulated to values of 39.35 +/- 0.09 and 25.56 +/- 0.11 mu mol g(-1) dry weight in seed and leaf extracts, respectively. Myrosinase has high activity in caper seeds, leaves, flowers, and flower bud tissues having the highest total activities in seed extracts (79.23 +/- 0.18 U). However, specific activities were the highest in flower bud extracts (200.44 +/- 0.09 U mg(-1) protein). The myrosinase protein migrated as a single band with a molecular weight of 65 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis and on Western blots probed with the myrosinase-specific 3D7 antibodies. Native gel electrophoresis revealed two putative myrosinase isoenzymes in seeds, leaves, and flower tissues. The caper homolog of the Arabidopsis thaliana TGG1 gene was differentially expressed in seeds, leaves, flowers, and flower buds with the highest expression levels in leaves and flower bud tissues.Öğe Interspecific diversity in root antioxidative enzyme activities reflect root turnover strategies and preferred habitats in wetland graminoids(Wiley-Blackwell, 2014) Yucel, Cagdas Kera; Bor, Melike; Ryser, PeterAntioxidant enzymes protect cells against oxidative stress and are associated with stress tolerance and longevity. In animals, variation in their activities has been shown to relate to species ecology, but in plants, comparative studies with wild species are rare. We investigated activities of five antioxidant enzymes - ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), peroxidase (POX), and superoxide dismutase (SOD) - in roots of four perennial graminoid wetland species over a growing season to find out whether differences in root turnover or habitat preferences would be associated with variation in seasonal patterns of antioxidant enzyme activities. The investigated species differ in their root turnover strategies (fine roots senesce in the fall or fine roots survive the winter) and habitat preferences (nutrient-poor vs. productive wetlands). Roots were collected both in the field and from garden-grown plants. Antioxidant enzyme activities were higher and lipid peroxidation rates lower in species with annual root systems, and for species of the nutrient-poor wetland, compared with perennial roots and species of productive wetlands, respectively. There was variation in the activities of individual antioxidant enzymes, but discriminant analyses with all enzymes revealed a clear picture, indicating consistent associations of antioxidant enzyme activities with the type of root turnover strategy and with the preferred habitat. We conclude that antioxidant enzyme activities in plant roots are associated with the species' ecological strategies and can be used as traits for the characterization of the species' position along plant economics spectrum.Öğe The involvement of gamma-aminobutyric acid shunt in the endoplasmic reticulum stress response of Arabidopsis thaliana(Elsevier Gmbh, 2020) Ozgur, Rengin; Uzilday, Baris; Bor, Melike; Turkan, IsmailThe endoplasmic reticulum (ER) is the main site of secretory protein production and folding and its homeostasis under environmental stress is vital for the maintenance of the protein secretory pathway. the loss of homeostasis and accumulation of unfolded proteins in the ER is referred to as ER stress. Although, gamma-aminobutyric acid (GABA) is an important regulator of stress response in plants, its roles during ER stress remains unclear. This study investigated the involvement of GABA in the ER stress response of plants. For this, changes in GABA metabolism under ER stress was analysed in Arabidopsis thaliana, then to study the response of the ER-folding machinery, plants were treated with exogenous GABA under ER stress. the antibiotic tunicamycin, which inhibits N-glycosylation was used to specifically induce ER stress. This stress up-regulated the expression of five glutamate decarboxylase (GAD) genes except GAD2 and GABA content of A. thaliana plants increased with an increasing concentration of tunicamycin (0.1 mu g ml(-1) and 0.25 mu g ml(-1)). Moreover, expressions of genes involved in the conversion of GABA to succinate was also induced, while genes involved in transport across plasma and mitochondrial membrane showed no response to ER stress. the exogenous treatment of plants with 1- and 5mM GABA increased plant performance under ER stress but 0.1 mM proved ineffective. Plants treated with GABA under ER stress had decreased expression of ER stress marker genes such as BIP1, BIP3 or CNX, but the expression of genes related to ER stress perception or ER-associated protein degradation showed no changes with respect to GABA treatments.Öğe Is there a room for GABA in ROS and RNS signalling?(Pergamon-Elsevier Science Ltd, 2019) Bor, Melike; Turkan, IsmailPlants have evolved different signalling pathways not only to maintain their life and survival but also for coping with different environmental stresses. Analysing and understanding the components of such sophisticated networks would contribute to improve crop performance and yield in challenging environments. Recent evidences suggest that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are major players in these signalling routes in plants although for long time they were considered only for their toxic effects. the unique nonprotein amino acid, y-aminobutyric acid (GAGA) has long been designated to be a signalling molecule in plants in relation to its function as a neurotransmission inhibitor in animals. All of these molecules have similarities and unique features hence to date several studies were conducted to decipher their mode of action in plants. Here we aimed to provide a new perspective to a plausible ROS and/or RNS signalling and GABA-shunt interaction by means of the most recent and relevant literature. We focused on Ca+2 signalling, polyamine biosynthesis, photorespiration, tricarboxylic acid (TCA) cycle and, a post-translation modification- succinylation- which are the most likely processes where a potential interplay between ROS, RNS and GABA-shunt might take place.
