Potassium-mediated Alleviation of Boron Toxicity in Sensitive and Tolerant Wheat (Triticum aestivum L.) Cultivars: Oxidative Stress, Antioxidant Response and Mineral Element Composition

Öz

Boron toxicity limits wheat productivity in boron-rich soils, yet the potential of potassium to alleviate boron-induced oxidative damage in cultivars with differing sensitivity remains poorly understood. This study investigated potassium-mediated mitigation of boron stress in two wheat (Triticum aestivum L.) cultivars, Bezostaya (sensitive) and Kutluk (tolerant). Germinated seeds were grown hydroponically under five treatment conditions (control, 5 mM B, 10 mM B, 5 mM B + 10 mM K and 10 mM B + 10 mM K). Growth parameters, chlorophyll content, oxidative stress markers (hydrogen peroxide [H₂O₂], malondialdehyde [MDA], proline), antioxidant enzyme activities (superoxide dismutase [SOD], catalase [CAT], ascorbate peroxidase [APX], guaiacol peroxidase [GPX], lipoxygenase [LOX]), and tissue mineral element concentrations (K, Cu, Na, Ca, Mg, Mn, Fe, Zn, B) were measured in shoot and root tissues. Boron exposure reduced growth and chlorophyll while increasing oxidative stress markers and enzyme activities. Tissue boron accumulated dose-dependently, whereas K, Ca, Mg, Na, Fe, Zn, Cu, and Mn concentrations declined significantly in most tissue-treatment combinations, indicating broad mineral nutrient disruption. Potassium supplementation partially reversed these effects by improving growth, reducing oxidative damage, restoring mineral element levels closer to control values and lowering boron accumulation. Enzyme activities remained elevated but below boron-only levels, suggesting reduced oxidative burden. The mitigation effect was more pronounced in the sensitive cultivar Bezostaya. These results indicate that potassium can reduce boron toxicity through modulation of antioxidant defense mechanisms and restoration of mineral nutrient balance, particularly in sensitive genotypes.

Anahtar Kelimeler

• Boron toxicity
• potassium
• wheat (Triticum aestivum L.)
• antioxidant enzymes
• mineral element composition

Etik Beyan

Ethics committee approval is not required for this study.

Hassas ve Toleranslı Buğday (Triticum aestivum L.) Çeşitlerinde Bor Toksisitesinin Potasyum Aracılı İyileştirilmesi: Oksidatif Stres, Antioksidan Yanıt ve Mineral Element Kompozisyonu

Öz

Bor toksisitesi, bor bakımından zengin topraklarda buğday verimliliğini sınırlayan önemli bir abiyotik stres faktörüdür. Bununla birlikte, potasyumun bor kaynaklı oksidatif hasarı farklı duyarlılığa sahip buğday çeşitlerinde nasıl hafiflettiği yeterince açıklığa kavuşturulamamıştır. Bu çalışmada, potasyumun bor stresini azaltıcı etkisi, iki ekmeklik buğday (Triticum aestivum L.) çeşidinde; bor duyarlı Bezostaya ve bor toleranslı Kutluk'ta araştırılmıştır. Çimlendirilmiş tohumlar hidroponik koşullarda beş uygulama grubunda (kontrol, 5 mM B, 10 mM B, 5 mM B + 10 mM K ve 10 mM B + 10 mM K) yetiştirilmiştir. Yaprak ve kök dokularında büyüme parametreleri, klorofil içeriği, oksidatif stres göstergeleri (hidrojen peroksit [H₂O₂], malondialdehit [MDA] ve prolin), antioksidan enzim aktiviteleri (süperoksit dismutaz [SOD], katalaz [CAT], askorbat peroksidaz [APX], guaiakol peroksidaz [GPX] ve lipoksigenaz [LOX]) ile mineral element konsantrasyonları (K, Cu, Na, Ca, Mg, Mn, Fe, Zn ve B) belirlenmiştir. Bor uygulamaları büyüme ve klorofil içeriğini azaltırken, oksidatif stres belirteçleri ile antioksidan enzim aktivitelerini artırmıştır. Doku bor birikimi uygulama dozuna bağlı olarak artarken, Na, K, Ca, Mg, Fe, Zn, Cu ve Mn konsantrasyonlarında önemli azalmalar gözlenmiş ve bunun geniş kapsamlı bir mineral besin dengesizliğine yol açtığı belirlenmiştir. Potasyum uygulaması ise büyümeyi iyileştirmiş, oksidatif hasarı azaltmış, mineral element düzeylerini kontrol değerlerine yaklaştırmış ve doku bor birikimini düşürerek bu olumsuz etkileri kısmen tersine çevirmiştir. Antioksidan enzim aktiviteleri bor uygulamalarına kıyasla daha düşük olmakla birlikte kontrol seviyelerinin üzerinde kalmış, bu durum oksidatif yükün azaldığını göstermiştir. Potasyumun iyileştirici etkisi, bor duyarlı Bezostaya çeşidinde daha belirgin olmuştur. Sonuç olarak, potasyumun özellikle duyarlı genotiplerde antioksidan savunma sistemini düzenleyerek ve mineral besin dengesini yeniden sağlayarak bor toksisitesini azaltabildiği ortaya konmuştur.

Anahtar Kelimeler

• Bor toksisitesi
• potasyum
• buğday (Triticum aestivum L.)
• antioksidan enzimler
• mineral element kompozisyonu

Etik Beyan

Bu çalışma için etik kurul onayı gerekmemektedir.

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