Study on the Correlation between Solanesol Accumulation and Expression of Gene Encoding Terpenoid Synthetic Enzymes in Tobacco

To reveal the impact of the genes encoding key enzymes in solanesol synthesis in tobacco, the UPLC (Ultra-performance Liquid Chromatography) was used to determine the solanesol contents of root, stem, and leaf, and real-time PCR assay was carried out to analyze the expression levels of genes encoding terpenoid synthetic enzymes at different development stages in tobacco cultivars Honghuadajinyuan and Zhongyan 90, whose solanesol contents are significantly different from each other. The correlations between the solanesol contents and the expression levels of these genes were also analyzed. The results showed that the trends of solanesol accumulation were consistent at different development stages in different organs of these cultivars i.e., the solanesol content of leaf was the highest while that of root was the lowest. The expression patterns of different terpenoid synthetic enzyme genes were not completely identical in these two cultivars. The expression levels of FPS, DXR, IPI, SPS, GGPPS increased gradually from the seeding stage to the flowering stage. The expression levels were the highest at the budding period in root, at the flowering period in stem and leaf, and then declined rapidly. The correlation analysis showed that the expression levels of DXS and GGPPS were negatively correlated with solanesol contents, but FPS, DXR, SPS and IPI exhibited extremely significant positive correlation with solanesol contents. The higher solanesol contents in Honghuadajinyuan may be caused by the higher expression levels of the genes. In addition, the expression level of IPI showed extremely significant positive correlation with that of DXS, FPS and SPS in tobacco root. The expression level of SPS has significantly positive correlation with FPS and IPI, but has significantly negative correlation with DXS in leaf. The expression level of IPI showed extremely significant positive correlation with HMGR in leaf. Which suggested these genes co-regulated the biosynthesis and accumulation of solanesol.