Rapid analysis of GBSS1 and Vinv genes expressed in potato tubers using microtubers produced in liquid culture medium.

KEY MESSAGE This study established a rapid method for the gene expression analysis in potato tubers. The use of microtubers would be useful for primary evaluation of tuber-expressed genes. In the development of transgenic potato or of potato with other genome modifications (e.g., genome editing or RNA-directed DNA methylation (RdDM) and so on) to improve tuber traits, analysis of the target gene is often difficult because of the long cultivation cycle (3-4 months), large areas required, numerous materials for plant cultivation, and considerable efforts needed to obtain transgenic tubers. We demonstrate here rapid and convenient analysis of gene expression in potato microtubers. Enough microtubers for expression analysis can be induced over about 4 weeks in a simple liquid medium in an Erlenmeyer flask. High-quality RNA and protein can be easily prepared from microtubers and used for northern blot, qRT-PCR, and western blot analyses without further purification. We investigated the expression of two tuber-expressed genes (GBSS1 and Vinv) in microtubers derived from the wild-type and from lines derived from RdDM-mediated transcriptional gene silencing. As expected, the expression of both genes was similar between microtubers and normal tubers. Furthermore, we demonstrated that microtubers can be used in western blot and confocal immunofluorescent microscopy analyses. These results suggest that expression analysis using microtubers is a convenient tool for the analysis of tuber-expressed genes such as GBSS1 and Vinv in potato.