Polar metabolites were extracted, derivatized and run on the GC-TOF-MS as described before (Ribeiro et al. 2014 (link)) but 5 mg of dry material was used instead of 20 mg. All volumes were stoichiometrically adjusted.
In order to confirm the sucrose trend from GC-TOF-MS, soluble carbohydrates were also determined as described previously (Ribeiro et al. 2014 (link)). The supernatant after starch extraction was injected into a Dionex HPLC system (ICS 5000 + DC) to analyse the soluble carbohydrate content, using a CarboPac PA 1, 4- × 250-mm column preceded by a guard column (CarboPac PA 1, 4 × 50 mm), and a gradient pump module (ICS 5000 Dual Pump, Dionex). Mono-, di-, and tri-saccharides were separated by elution in an increasing concentration of NaOH (20–350 mM) with a flow rate of 1 mL min−1. Peaks were identified by co-elution of soluble carbohydrate standards. Sugar quantity was corrected by mean of the internal standard (melezitose) and transformed to micrograms of sugar per milligram of dry material.
In order to confirm the sucrose trend from GC-TOF-MS, soluble carbohydrates were also determined as described previously (Ribeiro et al. 2014 (link)). The supernatant after starch extraction was injected into a Dionex HPLC system (ICS 5000 + DC) to analyse the soluble carbohydrate content, using a CarboPac PA 1, 4- × 250-mm column preceded by a guard column (CarboPac PA 1, 4 × 50 mm), and a gradient pump module (ICS 5000 Dual Pump, Dionex). Mono-, di-, and tri-saccharides were separated by elution in an increasing concentration of NaOH (20–350 mM) with a flow rate of 1 mL min−1. Peaks were identified by co-elution of soluble carbohydrate standards. Sugar quantity was corrected by mean of the internal standard (melezitose) and transformed to micrograms of sugar per milligram of dry material.
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