Tuzluluk Stresi Altında Çilekte (Fragaria × ananassa) Antiporterlerin Belirlenmesi ve Düzenlenmesi

Öz

Toprak tuzluluğu, bitki büyümesini ve verimini olumsuz yönde etkileyen başlıca abiyotik stres faktörlerinden biridir. Daha önce tuza toleranslı olduğu bildirilen çilek çeşidi Sweet Charlie, fizyolojik yanıtların değerlendirilmesi ile tuzluluk stresi altında antiporter genlerinin farklı düzenlenmesinin belirlenmesi ve karakterizasyonu amacıyla seçilmiştir. Toplamda, kültür çileğinde altı gen ailesine ait on adet antiporter tanımlanmıştır. SOS (Salt Overly Sensitive) ailesi üç üyeden (FaSOS1.1, FaSOS1.2 ve FaSOS1.3) oluşurken, SOS2, SOS3, SOS4 ve SOS5 aileleri sırasıyla tek bir gen ile temsil edilmiştir (FaSOS2, FaSOS3, FaSOS4 ve FaSOS5). NHX (katyon/H⁺ değiştirici) ailesi ise üç üyeden oluşmuştur (FaNHX1.1, FaNHX1.2 ve FaNHX2). Sweet Charlie çeşidi, 7 günlük stres uygulaması sonrasında 85 mM NaCl’ye karşılık gelen LT₅₀ değeri ile yüksek düzeyde tuz toleransı göstermiştir. Yaprak alanının korunması, stomatal düzenleme yoluyla nispi su içeriğinin sürdürülmesi, ozmotik uyum ve klorofil düzeylerinin devamlılığı gibi fizyolojik adaptasyonlar, kısa süreli tuzluluk stresinin zararlı etkilerinin azaltılmasına katkı sağlamıştır. Moleküler düzeyde ise, köklerde FaSOS1.2 ve FaSOS3 genlerinin yanı sıra hem kök hem de sürgünlerde FaNHX1.2 geninin artan ekspresyonu, bu genlerin tuzluluğun neden olduğu toksisitenin hafifletilmesinde rol oynayabileceğini göstermektedir. Kısa süreli tuzluluk stresi ayrıca hücresel hasara da neden olmuş; bu durum, artmış reaktif oksijen türleri (ROS) birikimi, yükselmiş malondialdehit (MDA) düzeyleri ve artan elektrolit sızıntısı ile ortaya konmuştur. Gelecekte yapılacak çalışmalarda, tuzluluk toleransındaki işlevsel rollerinin daha ayrıntılı olarak aydınlatılması amacıyla, ekspresyonu artış gösteren seçilmiş antiporter genlerinin (FaSOS1, FaSOS3 ve FaNHX1.2) Arabidopsis thaliana’da aşırı ekspresyonu üzerinde durulacaktır.

Anahtar Kelimeler

• Tuzluluk
• Antiporterler
• Gen düzenlenmesi
• SOS
• NHX

Proje Numarası

2016.10.05.1026

Teşekkür

Yazarlar, Bolu Abant İzzet Baysal Üniversitesi Bilimsel Araştırma Projeleri Koordinasyon Birimi tarafından sağlanan mali destek için teşekkür ederler (Proje No: 2016.10.05.1026).

Identification and Regulation of antiporters in Strawberry (Fragaria x ananassa) under salinity stress

Öz

Soil salinity is a major abiotic constraint that adversely affects plant growth and yield. The strawberry cultivar Sweet Charlie, previously reported as salt tolerant, was selected to evaluate physiological responses and to identify and characterize the differential regulation of antiporter genes under salinity stress. In total, ten antiporters were identified in cultivated strawberry, belonging to six gene families. The SOS (Salt Overly Sensitive) family comprised three members (FaSOS1.1, FaSOS1.2, and FaSOS1.3), while SOS2, SOS3, SOS4, and SOS5 were each represented by a single gene (FaSOS2, FaSOS3, FaSOS4, and FaSOS5). The NHX (cation/H⁺ exchanger) family included three members (FaNHX1.1, FaNHX1.2, and FaNHX2). The cultivar Sweet Charlie exhibited a high level of salt tolerance, with an LT₅₀ corresponding to 85 mM NaCl after 7 days of stress exposure. Physiological adaptations such as maintenance of leaf area, preservation of relative water content through stomatal regulation, osmotic adjustment, and sustained chlorophyll levels contributed to mitigating the detrimental effects of short-term salinity stress. At the molecular level, increased expression of FaSOS1.2 and FaSOS3 in roots, along with FaNHX1.2 in both roots and shoots, suggests their involvement in alleviating salt-induced toxicity. Short-term salinity stress also induced cellular damage, as evidenced by enhanced reactive oxygen species (ROS) accumulation, elevated malondialdehyde (MDA) levels, and increased electrolyte leakage. Future work will focus on the overexpression of selected upregulated antiporters (FaSOS1, FaSOS3, and FaNHX1.2) in Arabidopsis thaliana to further elucidate their functional roles in salinity tolerance.

Anahtar Kelimeler

• salinity
• antiporters
• gene regulation
• SOS
• NHX

Proje Numarası

2016.10.05.1026

Teşekkür

The authors are thankful for the financial support provided by the Bolu Abant Izzet Baysal University Scientific Research Projects Coordination Unit (Project No. 2016.10.05.1026).

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