Study on function of NtbHLH93 in sterol metabolism of tobacco by VIGS

To study the function of NtbHLH93, virus-induced gene silencing (VIGS) was used to downregulate NtbHLH93 expression in tobacco. The results showed that when NtbHLH93 expression was downregulated, the contents of total sterol, stigmasterol, cholesterol and β-sitosterol significantly decreased in pTRV2-NtbHLH93 tobacco seedlings. Transcriptome sequencing revealed that there were 259 differentially expressed genes in NtbHLH93 expression downregulated tobacco seedlings. KEGG pathway analysis indicated that two genes (Niben101Scf00063g13014.1 and Niben101Scf06249g03002.1) were upregulated in MEP (2-C-methyl-D-erythritol-4-phosphate) pathway, a terpenoid metabolism pathway in plastids. The sequences of the two genes were highly similar to geranylgeranyl diphosphate synthases (GGPPS) gene in MEP pathway, which suggested that the upregulation of Niben101Scf00063g13014.1 and Niben101Scf06249g03002.1 might relate to the inhibition of sterol synthesis.