Physiological and Molecular Effects of Exogenous Gibberellin (GA3) Treatment on Germination of Barley Seeds under Salt Stress

Öz

Salinity is considered as one of the most important factors restricting germination parameters including rate and percentage of seed germination in crops. This study focused on the alleviating role of exogenously applied 10 mg/L gibberellic acid (GA3) on barley (Hordeum vulgare L.) seeds during germination under salt stress (120 mM NaCl). Physiological and morphological changes, and differential gene expression at 3 days after imbibition (DAI) were determined and compared with or without gibberellic acid (GA3) under salt stress. Exogenous GA3 was found to increase the shoot and root length of germinated barley seeds under salt stress by 67 and 15%, respectively, compared to those treated with salinity alone. On the other hand, exogenous GA3 treatment significantly reduced ion leakage, osmolyte accumulation, and proline content under salinity. NaCl was found to decrease the expression of the HvABI5, HvABA7 and HvKO1 by 3, 10, and 33 fold, respectively, at 3 DAI, whereas addition of GA3 in root medium rescued the expression of these genes to control levels. Besides, exogenous GA3 significantly promoted the decreased mRNA level of HvGA2ox2 due to salinity during germination. This study may give insight into the relationship between salinity stress and the genes involved in GA3 metabolism and germination.

Anahtar Kelimeler

• Barley
• Germination
• GA3
• Salinity
• Proline
• HvKO1
• HvGA2ox21

Eksojen Gibberellin (GA3) Uygulamasının Tuz Stresi Altındaki Arpa Tohumlarının Çimlenmesine Fizyolojik ve Moleküler Etkileri

Öz

Tuzluluk, bitkilerde tohum çimlenme oranı ve yüzdesi gibi çimlenme parametrelerini kısıtlayan en önemli faktörlerden biri olarak kabul edilmektedir. Bu çalışma, tuz stresi (120 mM NaCl) altında çimlendirilen arpa (Hordeum vulgare L.) tohumlarına eksojen olarak uygulanan 10 mg/L giberellik asidin (GA3) stresi hafifletici rolüne odaklanmıştır. İmbibisyondan 3 gün sonra tuz stresi altında giberellik asit (GA3) ile veya onsuz gerçekleşen fizyolojik ve morfolojik değişiklikler ve farklılaşmış gen anlatımı belirlendi ve karşılaştırıldı. Eksojen GA3'ün, tuz stresi altında filizlenmiş arpa tohumlarının sürgün ve kök uzunluğunu, yalnızca tuz ile muamele edilenlere kıyasla sırasıyla %67 ve %15 arttırdığı bulundu. Öte yandan, eksojen GA3 uygulaması tuzluluk altında iyon sızıntısını, ozmolit birikimini ve prolin içeriğini anlamlı şekilde azaltmıştır. NaCl'nin imbibisyondan 3 gün sonra HvABI5, HvABA7 ve HvKO1 genlerinin anlatımını sırasıyla 3, 10 ve 33 kat azalttığı bulunurken, kök besiyerine GA3 eklenmesinin bu genlerin anlatım seviyelerini kontrol grubunun seviyesine çıkarmıştır. Ayrıca, eksojen GA3 tuz stresi altında çimlenen örneklerde HvGA2ox4'ün mRNA seviyesini anlamlı derecede azaltmıştır. Bu çalışma, tuzluluk stresi ile GA3 metabolizması ve çimlenme ile ilgili genler arasındaki ilişki hakkında fikir verebilir.

Anahtar Kelimeler

• Arpa
• Çimlenme;
• GA3
• Tuzluluk
• Prolin
• HvKO1
• HvGA2ox4

Kaynakça

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