(A) CNQX constitutive post embryo harvest treatment increases the percent of callus formation from embryos in the regeneration competent Hi-II line (chi-square test; n = 48; **p < 0.0001) and the regeneration recalcitrant B73 line (chi-square test; n = 48 for each genotype in each treatment; **p < 0.0001).
(B) Representative images and quantification of callus formation from embryo in the B73 line and quantification. Under CNQX constitutive post embryo harvest treatment, a larger mass of callus was obtained (t test; n = 24 for each treatment; **p <10‒8). Scale bars, 2 mm.
(C) Regeneration of the maize seedling’s first leaf and coleoptile in the recalcitrant B73 line comparing mock and CNQX constitutive post-leaf harvest treated samples with quantitative analysis showing more than 3× higher frequency of callus formation in CNQX-treated cells (chi-square test; n ≥ 34 for each treatment; **p < 0.0001) and improvement in callus size (t-test; n = 24; **p < 0.0001). Scale bars, 1 mm.
(D) Callus formation from B73 leaves with PAMD constitutive post leaf harvest treatment, showing an improvement in callus formation frequency (chi-square test; n ≥ 34 for each treatment; **p < 0.0001) and callus size due to treatment (t test; n = 34 for each treatment; **p < 0.001). Scale bars, 1 mm.