Fig. 2
Functional annotation of genes responsible for variations in 8-C-hexosyl-kaempferol O-hexoside content. A Manhattan plot displaying the GWAS results for 8-C-hexosyl-kaempferol O-hexoside content. B Gene model of Sc08g017430 (Me3GT) located 87.2 kb from the lead SNP 8:38593261, which is indicated by a vertical arrow. The causative SNP 8:38681061, which is located in exon 2 of Me3GT, is indicated by a red star. C Phylogenetic tree of Me3GT and glucosyltransferase genes from other species. Bootstrap values are indicated at each node. D HPLC chromatograms of the reaction products of Me3GT with UDP-D-xylose and either apigenin 5-O-glucoside, chrysin-5-O-glucoside, naringenin 7-O-glucoside, eriodictyol 7-O-glucoside, kaempferol 3-O-glucoside, quercetin 3-O-glucoside, pelargonidin-3-O-glucoside, or cyanidin-3-O-glucoside. E Expression level of Me3GT in leaf, root, stem, and among seven developmental stages (S1–S7) of storage root. F Reduced transcript expression of Me3GT in Me3GT-silenced cassava plants (CsCMV-Me3GT-1 and CsCMV-Me3GT-2) compared with the control (CsCMV-NC) in leaf. Bars indicate mean ± SD, n = 3. G Reduced levels of 8-C-hexosyl-kaempferol O-hexoside in Me3GT-silenced cassava plants (CsCMV-Me3GT-1 and CsCMV-Me3GT-2) compared with the control (CsCMV-NC) in leaf. Bars indicate mean ± SD, n = 3. H Boxplot displaying the relative content of 8-C-hexosyl-kaempferol O-hexoside based on the causative SNP 8:38681061. I SNPs identified in the coding sequence of Me3GT. The two shaded rows above are nucleotide polymorphisms of allele1 and allele2, while the two shaded rows below are the corresponding amino acids. The SNPs (SNP6-SNP13) are corresponding to those in Additional file 2: Table. S8. J Relative contents of 8-C-hexosyl-kaempferol O-hexoside between allele1 and allele2. K Enzymatic activity among six mutants (A6T, G80D, S101C, T145A, S146G, P334S) and allele1 and allele2. Different letters indicate significant differences at P < 0.05 based on Duncan’s multiple range tests. Bars indicate mean ± SD, n = 3