Biotechnology Letters, Vol.42, No.10, 2035-2047, 2020
Functional characterization of wheatmyo-inositol oxygenase promoter under different abiotic stress conditions inArabidopsis thaliana
The production of wheat is severely affected by abiotic stresses such as cold, drought, salinity, and high temperature. Although constitutive promoters are frequently used to regulate the expression of alien genes, these may lead to undesirable side-effects in transgenic plants. Therefore, identification and characterization of an inducible promoter that can express transgene only when exposed to stresses are of great importance in the genetic engineering of crop plants. Previous studies have indicated the abiotic stress-responsive behavior ofmyo-inositol oxygenase(MIOX) gene in different plants. Here, we isolated theMIOXgene promoter from wheat (TaMIOX). The in-silico analysis revealed the presence of various abiotic stress-responsivecis-elements in the promoter region. TheTaMIOXpromoter was fused with theUidAreporter gene and transformed intoArabidopsis thaliana. The T(3)single-copy homozygous lines were analyzed for GUS activity using histochemical and fluorometric assays. Transcript expression ofTaMIOX::UidAwas significantly up-regulated by heat (five fold), cold (seven fold), and drought (five fold) stresses as compared to transgenic plants grown without stress-induced conditions. TheCaMV35S::UidAplants showed very high GUS activity even in normal conditions. In contrast, theTaMIOX::UidAplants showed prominent GUS activity only in stress treatments (cold, heat, and drought), which suggests the inducible behavior of theTaMIOXpromoter. The substratemyo-inositol feeding assay ofTaMIOX::UidAplants showed lesser GUS activity as compared to plants treated in abiotic stress conditions. Results support that theTaMIOXpromoter could be used as a potential candidate for conditional expression of the transgene in abiotic stress conditions.