Overexpression of WsSGTL1 Gene of Withania somnifera Enhances Salt Tolerance, Heat Tolerance and Cold Acclimation Ability in Transgenic Arabidopsis Plants

Abstract

BackgroundSterol glycosyltrnasferases (SGT) are enzymes that glycosylate sterols which play important role in plant adaptation to stress and are medicinally important in plants like Withania somnifera. The present study aims to find the role of WsSGTL1 which is a sterol glycosyltransferase from W. somnifera, in plant’s adaptation to abiotic stress.MethodologyThe WsSGTL1 gene was transformed in Arabidopsis thaliana through Agrobacterium mediated transformation, using the binary vector pBI121, by floral dip method. The phenotypic and physiological parameters like germination, root length, shoot weight, relative electrolyte conductivity, MDA content, SOD levels, relative electrolyte leakage and chlorophyll measurements were compared between transgenic and wild type Arabidopsis plants under different abiotic stresses - salt, heat and cold. Biochemical analysis was done by HPLC-TLC and radiolabelled enzyme assay. The promoter of the WsSGTL1 gene was cloned by using Genome Walker kit (Clontech, USA) and the 3D structures were predicted by using Discovery Studio Ver. 2.5.ResultsThe WsSGTL1 transgenic plants were confirmed to be single copy by Southern and homozygous by segregation analysis. As compared to WT, the transgenic plants showed better germination, salt tolerance, heat and cold tolerance. The level of the transgene WsSGTL1 was elevated in heat, cold and salt stress along with other marker genes such as HSP70, HSP90, RD29, SOS3 and LEA4-5. Biochemical analysis showed the formation of sterol glycosides and increase in enzyme activity. When the promoter of WsSGTL1 gene was cloned from W. somnifera and sequenced, it contained stress responsive elements. Bioinformatics analysis of the 3D structure of the WsSGTL1 protein showed functional similarity with sterol glycosyltransferase AtSGT of A. thaliana. ConclusionsTransformation of WsSGTL1 gene in A. thaliana conferred abiotic stress tolerance. The promoter of the gene in W.somnifera was found to have stress responsive elements. The 3D structure showed functional similarity with sterol glycosyltransferases.

IbSIMT1, a novel salt-induced methyltransferase gene from Ipomoea batatas, is involved in salt tolerance

“…Therefore, the improved salt tolerance of the transgenic sweetpotato plants might be due, at least in part, to the enhanced ROS scavenging capacity (Zhang et al 2012b). Similar results were also observed in other reports (Fan et al 2012;Mishra et al 2013;Yang et al 2013;Liu et al 2014a, b). In addition, proline is an effective scavenger of singlet oxygen and hydroxyl radicals (Smirnoff and Cumbes 1989;Alia et al 2001).…”

“…It is usually induced by salt stress to enhance the timely dismutation of superoxide into oxygen and H 2 O 2 , which is subsequently removed through different pathways (Koca et al 2006;Zhang et al 2012b). Thus, SOD activity is often used to test the salt tolerance of plants (Mishra et al 2013;Yang et al 2013;Liu et al 2014a, b). In this study, the IbSIMT1-overexpressing sweetpotato plants had significantly higher SOD activity and significantly less H 2 O 2 accumulation compared to WT (Table 2; Fig.…”

Characterization of Arabidopsis sterol glycosyltransferase TTG15/UGT80B1 role during freeze and heat stress

“…These modifications do help in adaption of the plants to fit better in the environment. 13 In this study, we have shown the heat and chilling sensitivity of mutant and their restored lines by phenotypic observations and fluorescence response.…”

“…Analysis of lipid peroxidation assay by malondialdehyde (MDA) content which is a measure of heat stress was performed by the previous modified protocol. 13 The absorbance was measured at 532 and 600 nm. MDA concentration was calculated using the Lambert-Beer law with an extinction coefficient…”

“…RP-C18 column (250 £ 4.6 mm, 5 mm pore size) protected by guard column containing the same packing 29 with flow rate of 2 ml/min and injecting 20 ml of extract. 13 Sterols were eluted by isocratic solution of acetonitrile and water (95:5 v/v). Quantification of sterols were performed at 202 nm at 34 C, 60 min retention time with 2 ml/min flow rate delivery of mobile phase by injecting 20 ml of extract.…”