Fig. 3
Potentially functionally important genes involved in SGA and starch metabolism. a, Five putatively conserved genes (red color) and five diverged (orange color) genes between cultivars with high and low total SGA content in the proposed SGA biosynthesis pathway. C5-SD, delta(7)-sterol-c5(6)-desaturase; CAS1, cycloartenol synthase; GAME9, GLYCOALKALOID METABOLISM 9; HMGR, 3-hydroxy-3-methylglutaryl coenzyme-A reductase; HMG-CoA, 3-hydroxy-3-methylglutaryl-coenzyme A; LAS1, lanostetrol synthase; PGA1, POTATO GLYCOALKALOID BIOSYNTHESIS 1; PGA2, POTATO GLYCOALKALOID BIOSYNTHESIS 2; SMT1, sterol C24-methyltransferase; SGT1, galactosyltransferase; SGT2, glucosyltransferase; SGT3, glycosyltransferase; SQE, squalene epoxide; SQS, squalene synthase; SSR2, sterol side chain reductase 2. b, Potentially conserved (red color) and diverged (orange color) genes between potato accessions bred for starch industry and other usages. The proposed starch biosynthesis and degradation pathway in potato tubers are depicted. ADP-Glc, ADP-glucose; AGPase, ADP-glucose pyrophosphorylase; AM, amylose; Amy, α-amylase; AP, amylopectin; BAM, β-amylase; DBE, starch branching enzyme; DPE, disproportionating enzyme; G1P, glucose 1-phosphate; G6P, glucose 6-phosphate; GBSS, granule-bound starch synthase; Glc, glucose; GLT, glucose transporter; GPT, glucose 6-phosphate/phosphate translocator; GWD, α-glucan, water dikinase; LSF, Like starch-excess Four; MEX, maltose transporter; NTT, nucleotide translocator; PGM, phosphoglucomutase; PHO, α-glucan phosphorylase; PWD, phosphoglucan, water dikinase; Pi, inorganic pyrophosphate; SuSy, sucrose synthase; SS, starch synthase; SBE, starch branching enzymes; SEX4, starch excess 4; UGPase, UDP-glucose pyrophosphorylase; UDP-Glc, UDP-glucose; VGT, vacuolar glucose transporter. c, Expression pattern of Soltu.DM.05G018750.1 (GPT2.1) on a log2 scale in seven tissues of DM. In a and b, dashed arrows indicate steps containing multiple catalytic reactions