Dosage effects of the tb1-ref allele on total root length and crown root traits at 35 DAT. (A) Total root length and partition between crown roots and lateral roots. (B) Total number of crown roots. (C-F) Representative pictures of the crown region of: (C) modern maize inbred B73 (B73), (D) tb1-ref heterozygous mutant (tb1/Tb1, B73 background), (E) tb1-ref homozygous mutant (tb1/tb1, B73 background) and (F) Balsas teosinte. (G, H) Individual tillers and their associated crown roots initiating from the base of each stem in: (G) tb1-ref homozygotes and (H) Balsas teosinte. (I) Crown root number partition between the main stem and successive tillers (n = 12). (J) Positive correlation between the number of crown roots and number of tillers across genotypes. Shown is the standard error of the mean estimate. Bars with the same letter are not significantly different at α = 0.05.