Regulatory role of methylglyoxal in osmotic stress adaptation: Insights into the antioxidant defense, glyoxalase system, and osmoprotectant metabolism in maize seedlings

Öz

Methylglyoxal (MG) functions in plants as both a cytotoxic byproduct and a signaling molecule that regulates responses to abiotic stress. To investigate its dose-dependent effects, maize seedlings were subjected to polyethylene glycol (PEG)-induced osmotic stress combined with different MG concentrations (5, 10, 25, and 35 mM). Measurements included relative water content, oxidative stress markers, proline, polyamines, and antioxidant enzyme activities (SOD, CAT, APX, GPX), as well as glyoxalase (Gly I, Gly II) enzyme activities, along with the expression of related genes. Results showed that low MG levels, particularly 10 mM, significantly improved RWC, enhanced antioxidant and glyoxalase activities, upregulated genes involved in antioxidant defense and osmoprotectant biosynthesis, while downregulating genes related to proline and polyamine catabolism. These changes reduced oxidative damage and promoted the accumulation of osmoprotectants. By contrast, higher MG doses increased oxidative stress, MG accumulation, and reduced stress tolerance. Overall, MG exhibited a concentration-dependent dual role in osmotic stress tolerance: acting as a beneficial signaling molecule at low levels but exerting toxicity at higher concentrations. This study highlights MG’s regulatory role in stress adaptation and provides a theoretical basis for its potential application in improving drought resilience in crops.

Anahtar Kelimeler

• Methylglyoxal
• osmotic stress
• Zea mays
• polyamine
• antioxidant and glyoxalase system

Metilglioksalın ozmotik stres adaptasyonundaki düzenleyici rolü: Mısır fidelerinde antioksidan savunma, glioksalaz sistemi ve ozmoprotektan metabolizmasına ilişkin görüşler

Öz

Metilglioksal (MG), bitkilerde hem sitotoksik bir yan ürün hem de abiyotik strese verilen yanıtları düzenleyen bir sinyal molekülü olarak işlev görür. Doza bağlı etkilerini araştırmak için mısır fideleri, farklı MG konsantrasyonları (5, 10, 25 ve 35 mM) ile birleştirilmiş polietilen glikol (PEG) kaynaklı ozmotik strese tabi tutuldu. Ölçümler, nisbi su içeriği, oksidatif stres belirteçleri, prolin, poliaminler ve antioksidan enzim aktiviteleri (SOD, CAT, APX, GPX) ile glioksalaz (Gly I, Gly II) enzim aktivitelerinin yanı sıra ilgili genlerin ekspresyonunu da içeriyordu. Sonuçlar, özellikle 10 mM olan düşük MG seviyelerinin, RWC'yi önemli ölçüde iyileştirdiğini, antioksidan ve glioksalaz aktivitelerini artırdığını, antioksidan savunma ve ozmoprotektan biyosentezinde yer alan genleri yukarı düzenlerken, prolin ve poliamin katabolizmasıyla ilgili genleri aşağı düzenlediğini gösterdi. Bu değişiklikler oksidatif hasarı azalttı ve ozmoprotektanların birikimini destekledi. Buna karşılık, daha yüksek MG dozları oksidatif stresi ve MG birikimini artırmış ve stres toleransını azaltmıştır. Genel olarak, MG, ozmotik stres toleransında konsantrasyona bağlı ikili bir rol sergilemiştir: düşük seviyelerde faydalı bir sinyal molekülü görevi görürken, daha yüksek konsantrasyonlarda toksisite yaratmaktadır. Bu çalışma, MG'nin stres adaptasyonundaki düzenleyici rolünü vurgulamakta ve bitkilerde kuraklığa dayanıklılığı artırmadaki potansiyel uygulaması için teorik bir temel sunmaktadır.

Anahtar Kelimeler

• Metilglioksal
• ozmotik stres
• Zea mays
• poliamin
• antioksidan ve glioksalaz sistemi

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