Premature endocycle onset in Zmatr endosperm. A, The mean C-values in ATR-WT and Zmatr endosperm at five developmental stages between 10 and 19 DAP. All analyses were carried out from at least three kernels from three independent cobs for each genotype. Values are means ± se; n = 9–11. Significantly different (ns, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001, Student’s t-test). See also Supplemental Data Set S1. B, Distribution of endosperm nuclei (expressed as a percentage of the total number of nuclei) among different ploidy classes in 19-DAP ATR-WT and Zmatr endosperms. All analyses were carried out from at least three kernels from three independent cobs for each genotype. Values are means ± se; n = 9–11 (ns, not significant; P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001, Student’s t-test). See also Supplemental Data Set S1.