Metabolite analysis
Sugar-phosphates were extracted as previously described by Noguchi et al. (2018). Leaves were sampled under illumination at 1,100 µE m-2 s-1 in ambient air (40 Pa CO2, 21kPa O2, 25 oC), and immediately frozen in liquid N2. The frozen leaves were ground with a mortar and pestle in liquid N2. Methanol was added to the homogenized leaves, and same volume of a solution containing internal standards (100 µM PIPES and 100 µM methionine sulfone) were mixed after vortex. After centrifugation, the resulting supernatants were filtered through a 3 kDa cut-off filter (Millipore) at 16,100×g at 4oC for 30 min. The sugar-phosphates were separated by capillary electrophoresis-triple quadrupole-mass spectrometry (CE-QQQ-MS; 7100 Capillary Electrophoresis, MS; 6420 Triple Quad LC/MS, Agilent Technologies, USA) with multi reaction monitoring mode as described previously (Miyagi et al. 2010, 2019). All CE-QQQ-MS data were processed using the Agilent MassHunter software (Agilent Technologies).