Figure 1.

RBG1 activation rice mutants display the big grain phenotype. (a) Comparison of seed morphology among segregated WT/sWT, heterozygous (RBG1_Act‐He) and homozygous (RBG1_Act‐Ho) lines of the RBG1 activation mutant M35973. (b) Relative location of insertion sites of the RBG1_Act mutant and its three allelic mutants, M37341 (A1), M37342 (A2) and M82594 (A3), and the non‐allelic mutant M44256. The numbers in parentheses indicate the distances of the CaMV35S enhancers within the T‐DNA from the translation initiation codon ATG of RBG1. The scale in Kb marks the location on rice chromosome 11. (c) Four RBG1_Act allelic mutants display big grain phenotypes, as compared with WT, which correlates with the overexpression of RBG1 in the mutant seedlings. n = 30 for each line. (d) Overexpression of RBG1 under the control of the Ubi promoter (RBG1‐Ox lines) enhances grain size, while underexpression by RNA interference (RBG1‐Ri lines) slightly reduces grain size. The yellow dashed line indicates WT grain length. Grain morphology and 1000‐seed weight were compared with those of WT. n = 18 for each line. The numbers above bars are % relative to the value in WT.