Krom Stresine Maruz Kalan Mısırda Dışsal Sistein Uygulamasının Etkileri

Sistein (Cys), kükürt metabolizmasının ilk organik kükürtlü bileşiğidir. Cys dahil kükürt metabolizmasınınürünleri, bitkilerin ağır metal ve oksidatif strese karşı cevaplarında biyolojik fonksiyonlara sahiptir. Bunedenle bu araştırmada, mısır (Zea mays L. cv. Bora) fidelerinin yapraklarında Cys'in krom (Cr) stresininetkilerini hafifletme üzerindeki etkileri araştırılmıştır. Hidroponik olarak yetiştirilen fidelerin köklerine 7gün süreyle Cr stresi (100 μM) ve Cr ile kombine şekilde Cys (500 μM) uygulanmıştır. Cr stresi büyümedeazalma, kloroz ve yapraklarda kıvrılma gibi toksisite semptomlarına neden olmuştur. Cr stresi, bağıl suiçeriğini (BSİ), -aminolevulinik asit dehidrataz (ALAD) aktivitesini, klorofil ve protein içerikleriniazaltmıştır. Diğer taraftan, Cr yapraklarda süperoksit dismutaz (SOD) ve katalaz (CAT) aktiviteleriniazaltırken, peroksidaz (POD) aktivitesini artırmıştır. İlaveten, Cr malondialdehit (MDA) birikimi ve sisteiniçeriğini arttırmıştır. Kök ortamına dışsal Cys uygulaması, büyümedeki Cr teşvikli inhibisyonu azaltmıştır.Dışsal Cys uygulaması Cr stresi koşullarında klorofil birikimini ve sistein içeriğini artırmıştır. Ayrıca Cysuygulaması, SOD ve CAT aktivitelerini arttırmış ve Cr teşvikli MDA birikimini önemli düzeyde azaltmıştır.Bu sonuçlar, dışsal Cys uygulamasının Cr stresinin neden olduğu oksidatif stresin olumsuz sonuçlarınıazalttığını göstermektedir.

Effects of Exogenous Cysteine Application on Maize Exposed to Chromium Stress

Cysteine (Cys) is the first organosulfur compound of sulfur metabolism. The products of sulfur metabolism including Cys have biological functions in responses to heavy metal stress and oxidative stress. In this study, therefore, the effects of Cys on alleviating chromium (Cr) toxicity in the leaves of maize (Zea mays L. cv. Bora) seedlings were investigated. Hydroponically grown seedlings were subjected to Cr stress (100 μM) and in combination with Cys (500 μM) for 7 days. Cr stress resulted in toxicity symptoms such as reduced growth, chlorosis, and rolling in leaves. Cr stress decreased the relative water content (RWC), -aminolevulinic acid dehydratase (ALAD) activity, and chlorophyll and protein contents. On the other hand, Cr decreased activities of superoxide dismutase (SOD) and catalase (CAT) in leaves, while increased the activity of peroxidase (POD). In addition, Cr increased the accumulation of malondialdehyde (MDA) and cysteine contents. Exogenous application of Cys to rooting media alleviated Cr-induced growth suppression. Exogenous Cys promoted the chlorophyll accumulation and cysteine content under Cr stress. Moreover, application of Cys increased the activities of SOD and CAT, and markedly diminished Cr-induced MDA accumulation. These results suggest that the exogenous application of Cys reduced the negative consequences of oxidative stress caused by Cr stress.

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