Table 3.

Suc Feeding Leads to Increased AGPase Redox Activation, Increased Starch Synthesis, and Decreased Hexose Phosphate Levels in Discs from Growing Tubers

Parameter	Control	200 mM Suc
Suc content (μmol/g fresh wt)	11.6 ± 0.4	22.2 ± 1.4
AGPase activation [Vsel/Vred] (%)	33 ± 2	49 ± 3
Starch synthesis (% of total 14C absorbed)	40 ± 3	59 ± 3
Hexose phosphate level (nmol/g fresh wt)	225 ± 20	148 ± 11

Tuber discs were cut from an intact growing tuber and incubated in buffer with and without 200 mM Suc for 2 h before they were either washed three times to analyze their Suc content or frozen immediately in liquid nitrogen to measure hexose phosphate levels and AGPase activity under selective (Vsel; −DTT) and reductive (Vred; +DTT) assay conditions. In parallel samples, 2 mM ¹⁴C-Glc kBq/μmol specific activity of 18.5) was provided to measure label incorporation into starch. Results are means ± se (n = 3 replicate measurements on different discs from the same tuber).