Fig. 6.

Relationships between three phenolic acids and five biosynthetic enzymes in diploid potatoes. A and H, The levels of CGA, CA, and FA of tuber peel (A) or flesh (H) in three diploid lines from the S. stenotomum group. FA level of tuber flesh or peel is extremely low in all three lines. Data are presented as means ± SD (n = 3 biological replicates). (B-F) and (H -M), The expression levels of HQT, HCT, PAL, CSE, and 4CL in tuber flesh (B-F) or peel (H -M) of three varieties. The expression level of the candidate gene in C107 was set as 1, and was used to normalize against the results from other samples. Data are presented as means ± SD (n = 3 biological replicates). G and N, Pearson correlation coefficients were calculated using the value of CGA level and expression of the biosynthetic enzyme in tuber peel (G) or flesh (N) of the three varieties (n = 3 biological replicates). The data was presented using a heatmap. The dark color indicates a high correlation rate. The CGA content of tuber peel was co-related with the expression levels of HQT and HCT, not with PAL, while the CGA content of tuber flesh was co-related with the expression level of all three enzymes. In addition, expressions of CSE and 4CL were negatively co-related with the CGA contents of tuber peel and flesh.