Fig. 3: Formation of PA precursors in different maize varieties expressing GmANR1.

Selected ion chromatograms of catechin and epicatechin (m/z = 289.0718 ± 10 ppm), as well as 4β-(S-cysteinyl)-catechin and 4β-(S-cysteinyl)-epicatechin (m/z = 408.0759 ± 10 ppm) in seeds of untransformed and transgenic ST (a) and OSA (c) maize. Peak areas of 4β-(S-cysteinyl)-epicatechin and ratio of 4β-(S-cysteinyl)-epicatechin/4β-(S-cysteinyl)-catechin in ST, ST-GmANR1, OSA and OSA-GmANR1 are shown in histograms. Data are presented as mean ± S.D. (n = 3, independent biological replicates). Asterisks denote significant difference relative to wild-type ST or OSA at P < 0.01 determined by two-tailed Student’s t-test. b Phloroglucinolysis of PAs extracted from seeds of ST, ST-GmANR1 and HiII-GmANR1 using procyanidin dimer B2 as standard. Left, selected ion chromatograms of epicatechin monomers (m/z = 289.0718 ± 10 ppm); right, selected ion chromatograms of epicatechin-phloroglucinol (m/z = 413.0876 ± 10 ppm). d MS/MS spectra of 4β-(S-cysteinyl)-epicatechin in the standard and PAs extracted from seeds expressing GmANR1. SD, chemical standards; ST, Suntava maize; OSA, Osage maize; HiII-GmANR1, HiII maize expressing GmANR1 (line GmANR1-24); ST-GmANR1, seeds from genetic cross between ST and GmANR1-24; OSA-GmANR1, seeds from genetic cross between OSA and GmANR1-24. Red arrows indicate peak representing cysteinyl-epicatechin. Source data for Fig. 3a and Fig. 3c are provided in the Source Data file.