Fig. 1: The Zmer mutants have compact plant architecture and larger shoot apical meristems.

a CRISPR/Cas9 editing generated different frameshift alleles for the Zmers. The positions of guide RNAs are indicated by red arrows on the gene models. b Representative images of mature maize plants illustrate that mutations in ZmER1 and its paralogs significantly reduce plant height. c Statistic analysis of plant height in various Zmer mutants. Different letters indicate statistically significant groups at P  <  0.05 (one-way ANOVA with post hoc Tukey’s multiple comparison test). Although the Zmer1;Zmer2, Zmer1;Zmerl and the triple mutants are classified within the same group, the triple mutant is significantly shorter than double mutants as determined by a two-sided unpaired Student t-test. The exact p-values are shown in the figure. d Images of representative cleared SAMs, meristem height and width are marked by the white arrows. Zmer1 single mutants, and Zmer1;Zmer2 double mutants have increased SAM width and reduced SAM height as quantified in (e and f). g In situ hybridization analysis shows ZmER1, ZmER2, and ZmERL are expressed in the SAM, with stronger signals in the leaf primordia. Each experiment is independently repeated three times, yielding consistent results. n represents the number of samples (c, e, and f). Scale bars, 20 cm (b), 50 μm (d) and 100 μm (g). For e and f, data are presented as means ± s.d. p-values are calculated using a two-sided t-test, for b–f, phenotypic analyses use the cr1 alleles for all three genes. Superscript “cr1” is omitted for space. Source data for statistical analysis in c, e, and f are available in the Source Data file.