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In plant cells, the nucleus DNA is considered the primary site of injury by the space environment, which could generate genetic alteration. As the part of genomic mutation, genetic variation in the promoter region could regulate gene expression. In the study, it is observed that there is a deletion in the upstream regulatory region of the <i>1-deoxy-<span style="font-variant: small-caps;">d</span>-xylulose-5-phosphate synthase 1</i> gene (<i>PpDXS1</i>) of <i>Poa pratensis</i> dwarf mutant and the <i>PpDXS1</i> transcript abundance is lower in the dwarf mutant. It is indicated that the deletion in the promoter region between wild type and dwarf mutant could be responsible for the regulation of <i>PpDXS1</i> gene expression. The <i>PpDXS1</i> promoter of dwarf mutant shows a lower activity as determined by dual luciferase assay in <i>Poa pratensis</i> protoplast, as well as the <i>GUS</i> activity is lower in transgenic <i>Poa pratensis</i> plant. To further investigate the effect of the deletion in the promoter region on <i>PpDXS1</i> transcript accumulation, the transient assay and yeast one-hybrid experiment demonstrate that the deletion comprises a motif which is a target of G-box binding factor (GBF1), and the motif correlates with an increase in transactivation by GBF1 protein. Taken together, these results indicate that the deletion in the promoter of <i>PpDXS1</i> isolated from dwarf mutant is sufficient to account for the decrease in <i>PpDXS1</i> transcript level and GBF1 can regulate the <i>PpDXS1</i> gene expression, and subsequently affect accumulation of various isoprenoids throughout the plant.