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 of myo-inositol oxygenase (MIOX) gene in different plants. Here, we isolated the MIOX gene promoter from wheat (TaMIOX). The in-silico analysis revealed the presence of various abiotic stress-responsive cis-elements in the promoter region. The TaMIOX promoter was fused with the UidA reporter gene and transformed into Arabidopsis thaliana. The T3 single-copy homozygous lines were analyzed for GUS activity using histochemical and fluorometric assays. Transcript expression of TaMIOX::UidA was 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. The CaMV35S::UidA plants showed very high GUS activity even in normal conditions. In contrast, the TaMIOX::UidA plants showed prominent GUS activity only in stress treatments (cold, heat, and drought), which suggests the inducible behavior of the TaMIOX promoter. The substrate myo-inositol feeding assay of TaMIOX::UidA plants showed lesser GUS activity as compared to plants treated in abiotic stress conditions. Results support that the TaMIOX promoter could be used as a potential candidate for conditional expression of the transgene in abiotic stress conditions.

中文翻译：

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不同非生物胁迫条件下拟南芥小麦肌醇加氧酶启动子的功能表征

小麦的生产受到寒冷、干旱、盐分和高温等非生物胁迫的严重影响。尽管组成型启动子经常用于调节外源基因的表达，但这些可能会导致转基因植物出现不良副作用。因此，鉴定和表征仅在暴露于胁迫时才能表达转基因的诱导型启动子在作物植物的基因工程中具有重要意义。先前的研究表明，肌醇加氧酶 (MIOX) 基因在不同植物中具有非生物胁迫响应行为。在这里，我们从小麦 (TaMIOX) 中分离出 MIOX 基因启动子。计算机分析揭示了启动子区域中存在各种非生物胁迫响应顺式元件。TaMIOX 启动子与 UidA 报告基因融合并转化到拟南芥中。使用组织化学和荧光测定法分析 T3 单拷贝纯合系的 GUS 活性。与没有胁迫诱导条件下生长的转基因植物相比，TaMIOX::UidA 的转录表达在热（5 倍）、冷（7 倍）和干旱（5 倍）胁迫下显着上调。CaMV35S::UidA 植物即使在正常条件下也显示出非常高的 GUS 活性。相比之下，TaMIOX::UidA 植物仅在胁迫处理（冷、热和干旱）中显示出显着的 GUS 活性，这表明 TaMIOX 启动子的诱导行为。与在非生物胁迫条件下处理的植物相比，TaMIOX::UidA 植物的底物肌醇喂养测定显示出较低的 GUS 活性。