Quantification of Plant Hormones

The standard IAA, IAA-Asp, JA, MeJA, and SA were purchased from Sigma-Aldrich (St. Louis, MO, USA), and ABA and JA-Ile were from OlChemIm (OlChemIm, Olomouc, Czech Republic). The internal standards were ²H₆ABA (Olchemin) for ABA, 10-dihydro-JA (DHJA; Olchemin) for JA, JA-Ile, and MeJA, D₂-IAA (Sigma-Aldrich) for IAA and IAA-Asp, and naphthalene acetic acid (NAA; internal standards) for SA. The standard momilactone A was kindly provided by Dr. Morifumi Hasegawa of College of Agriculture, Ibaraki University. The standard naringenin and sakuranetin were purchased from Extrasynthèse (Genay, France).