Abstract: Steroidal glycoalkaloids (SGAs) are a family of secondary metabolites that closely associate with the eating and processing qualities of potato tuber. In the present study, GGE-Biplot was used to analyze the transcriptional gene expression of seven genes that involved in the SGAs biosynthesis pathway. The microtubers of five varieties (genotypes) were incubated for 6, 12 and 24 h under red light, and the expression of seven genes were measured with RT-PCR and further analyzed via GGE-Biplot. The data indicated that the expression levels of pvs1, sgt1 and sgt3 were significantly higher among all tested genes. In addition, the transcriptional abandon of sgt3 was high and stable in all tested genotypes, but showed less stability among the light treatment durations. The very similar expression patterns of seven genes were observed for both 12 and 24 h treatments, while expressions of all except pvs1 were relatively lower after 6 h treatment. Among all tested genotypes, similar expression patterns of all genes were observed for HA and Zh-3. The genes that mediated different stages of SGAs biosynthesis also showed great variations among genotypes. Therefore, the results demonstrated that GGE-Biplot is a very useful tool to analyze and display the differential expression profile of seven key genes in potato tubers under red light illumination. According to the quantitative data, the results also presented the relationship among treatments and genotypes. The outcome of this study thus provides valuable reference for future study on SGAs biosynthesis, as well as the potato tuber quality improvement via manipulating the SGAs biosynthesis.

Key words: Potato, GGE-Biplot, steroidal glycoalkaloids, gene expression