CRISPR/Cas9-mediated mutagenesis of the dihydroflavonol-4-reductase-B (DFR-B) locus in the Japanese morning glory Ipomoea (Pharbitis) nil

CRISPR/Cas9 technology is a versatile tool for targeted mutagenesis in many organisms, including plants. However, this technique has not been applied to the Japanese morning glory (Ipomoea [Pharbitis] nil), a traditional garden plant chosen for the National BioResource Project in Japan. We selected dihydroflavonol-4-reductase-B (DFR-B) of I. nil, encoding an anthocyanin biosynthesis enzyme, as the target gene, and changes in the stem colour were observed during the early stages of plant tissue culture by Rhizobium [Agrobacterium]-mediated transformation. Twenty-four of the 32 (75%) transgenic plants bore anthocyanin-less white flowers with bi-allelic mutations at the Cas9 cleavage site in DFR-B, exhibiting a single base insertion or deletions of more than two bases. Thus, these results demonstrate that CRISPR/Cas9 technology enables the exploration of gene functions in this model horticultural plant. To our knowledge, this report is the first concerning flower colour changes in higher plants using CRISPR/Cas9 technology.