Fig. 1. Expression of anthocyanin synthesis-related genes in rice leaves and grains. Values in grids indicate gene expression in FPKM (fragment per kilobase per million reads) revealed by transcriptome analysis. CHS, Chalcone synthase; CHI, Chalcone isomerase; F3H, Flavanone 3-hydroxylase; F3ʹH, Flavonoid 3ʹ-hydroxylase; DFR, Dihydroflavonol reductase; ANS, Anthocyanidin synthase; UGT, UDP-glycosyltransferase.

Fig. 2. Phenotype of black rice variety Zinuo transgenic lines and yield-related trait comparison. A, OsC1 CRISPR/Cas9 target and mutations in knockout lines (ZN-OsC1-Ko-23 and ZN-OsC1-Ko-24). The target region is indicated in green, and red dashes (‘-’) indicate deletions. B, Leaf color of wild-type Zinuo and its knockout lines at the booting stage. Scale bar, 10 cm. C, Hull and grain color of the wild-type Zinuo and its knockout lines at the maturity stage. Scale bars, 1 cm. D, Comparison of panicle number per plant, grain number per panicle, and 1000-grain weight between Zinuo and its knockout lines. Comparisons were performed using one-way analysis of variance, followed by Tukey’s honestly significant difference tests to assess pairwise differences between wild-type and knockout lines. * and ** indicate significances at 0.05 and 0.01 levels, respectively.