Abstract
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 1-deoxy-d-xylulose-5-phosphate synthase 1 gene (PpDXS1) of Poa pratensis dwarf mutant and the PpDXS1 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 PpDXS1 gene expression. The PpDXS1 promoter of dwarf mutant shows a lower activity as determined by dual luciferase assay in Poa pratensis protoplast, as well as the GUS activity is lower in transgenic Poa pratensis plant. To further investigate the effect of the deletion in the promoter region on PpDXS1 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 PpDXS1 isolated from dwarf mutant is sufficient to account for the decrease in PpDXS1 transcript level and GBF1 can regulate the PpDXS1 gene expression, and subsequently affect accumulation of various isoprenoids throughout the plant.
Highlights
Terpenoids are a large group of primary and secondary metabolites involved in plant life processes, and there is mounting evidence that metabolites such as phytohormones and chlorophyll can regulate their growth and development [1,2]
Poa pratensis seeds were carried on a space flight for 18 days on the 20th returnable satellite and returned to the ground to plant together with the wild type in the same growth conditions
We isolated 1-deoxy-D-xylulose-5-phosphate synthase 1 gene (PpDXS1) from Poa pratensis wild-type (WT) and dwarf mutant (A16) plant respectively and found no significant mutation in the coding region, while the PpDXS1 gene expression is higher in the wild type (WT) compared with A16
Summary
Terpenoids are a large group of primary and secondary metabolites involved in plant life processes, and there is mounting evidence that metabolites such as phytohormones and chlorophyll can regulate their growth and development [1,2]. Mutations in the upstream promoter of genes will affect gene expression, which lead to changes in the gene function associated with plant growth and development. The insertion of transposable elements in the promoter region of maize genes exhibit activation of gene expression [15] Another example by Mernke et al [16] was that the rearrangement caused by insertion of a retroelement-derived sequence in the promoter region of major facilitator superfamily transporter gene (mfsM2) resulted in its overexpression, which is responsible for the appearance and subsequent spread of multidrug resistance in vineyards. Several studies regarding DXS gene expression and the cis-regulatory elements of DXS promoter have been performed, the relationship between the insertion/deletion in the promoter of DXS gene caused by space mutation and its gene expression have not been reported, which is worth further investigation. By transient assay and yeast one-hybrid experiment, the transcription factor could activate the PpDXS1 transcript accumulation, leading to the subsequent accumulation of various isoprenoids throughout the plant
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