Expression of SbGSTU (tau class glutathione S-transferase) gene isolated from Salicornia brachiata in tobacco for salt tolerance

Abstract

Tau class glutathione transferases (GSTU) genes are plant specific, induced by different abiotic stress, and important for protecting plants against oxidative damage. GST gene was isolated using 5' RACE from an extreme halophyte Salicornia brachiata, cloned, sequenced and its protein structure was predicted. Transcript profiling of SbGST gene expression was studied under different abiotic stress conditions and plant growth regulator treatments, viz. salt, cold, drought, ABA and salicylic acid, with time period point and concentration point. The expression of SbGST gene was up-regulated in all stress conditions, except SA treatment. Seed germination percentage, GST enzyme assay, fresh weight and other growth parameters (root length, shoot length and leaf area) were studied and results indicate that over-expression of SbGST gene in transgenic tobacco leads to enhanced seed germination and growth under salt stress. Transgenic lines were evaluated for their performance under salt stress and tobacco plants over-expressing SbGST showed higher seed germination and survival compared to wild type. These results confirm that expression of SbGST gene is up-regulated by different stresses and over-expression of tau class SbGST gene in transgenic tobacco plays a vital role in abiotic stress tolerance. SbGST gene expressed conspicuously under salt stress leading to enhance seed germination and better growth. Furthermore, GST is a potential candidate gene to be used in genetic engineering for enhancing abiotic stress tolerance.