Evaluation of salt tolerance in STO transformed Arabidopsis thaliana and Nicotiana tabacum plants

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Biyolojik Bilimler Bölümü, Türkiye

Tezin Onay Tarihi: 2004

Öğrenci: FEYZA SELÇUK

Danışman: HÜSEYİN AVNİ ÖKTEM

Özet:

Salinity is one of the limiting factors of crop development. Together with causing water loss from plant tissues, salinity also leads to ion toxicity. Under salt stress, increase in Ca+2 concentration in cytosol can decrease the deleterious effects of stress. The binding of Ca+2 to calmodulin initiates a signaling cascade involving the activation of certain transcription factors like STO and STZ. This signal transduction pathway regulates transport of proteins that control net Na+ influx across the plasma membrane and compartmentalization into the vacuole. Previously Arabidopsis STO was identified as a repressor of the yeast calcineurin mutation. Genetical and molecular characterization of STO; a putative transcription factor that takes role in salt stress tolerance can provide a better understanding in the mechanism of salt tolerance and development of resistance in higher plants. The aim of the present study was to amplify and clone the Arabidopsis thaliana sto gene in plant transformation vectors and use them for the transformation of Nicotiana tabacum and Arabidopsis thaliana plants via Agrobacterium tumefaciens mediated gene transfer systems. T0 and T1 progeny of transgenic plants carrying sto were analysed for the stable integration of transgenes, segregetion patterns, expression of the gene and their tolerance to salt stress. The results of the study showed that all transgenic Nicotiana tabacum lines are differentially expressing a transcript that is lacking in control plants and most transgenic lines exhibited higher germination percentages and fresh weights, lower MDA contents under salt stress. On the other hand overexpression of sto in Arabidopsis plants did not provide an advantage to transgenic plants under salt stress, however the anti-sense expression of sto caused decreased germination percentages even under normal conditions. According to the sto