1Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kitaku, Kyoto 603-8555, Japan 2Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusaku, Nagoya 464-8601, Japan 3Center for Plant Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603- 8555, Japan 4Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 5School of Agriculture, Meiji University, 1-1-1, Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan 6Faculty of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan 7Center for Ecological Research, Kyoto University, Hirano 2-509-3, Otsu, Shiga 520-2113, Japan 8Faculty of Agriculture, Ryukoku University, 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga 520-2194, Japan 9Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto 606-8522, Japan 10Biotechnology Research Department, Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Center, 74 Oji, Kitainayazuma, Seika-cho, Soraku-gun, Kyoto 619- 0244, Japan 11Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan 12Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan *Corresponding author. E-mail: seisuke@cc.kyoto-su.ac.jp
Received: 21 Dec 2020 Revised: 09 Mar 2021 Accepted: 07 Apr 2021 Published online: 01 Jun 2021
Abstract
Since ancient times, humans have bred several plants that we rely on today. However, little is known about the divergence of most of these plants. In the present study, we investigated the divergence of Mibuna (Brassica rapa L. subsp. nipposinica L. H. Bailey), a traditional leafy vegetable in Kyoto (Japan), by combining genetic analysis and a survey of ancient literature. Mibuna is considered to have been bred 200 years ago from Mizuna, another traditional leafy vegetable in Kyoto. Mibuna has simple spatulate leaves, whereas Mizuna has characteristic serrated leaves. The quantitative trait loci (QTL) and gene expression analyses suggested that the downregulation of BrTCP15 expression contributed to the change in the leaf shape from serrated to simple spatulate. Interestingly, the SNP analysis indicated that the genomic region containing the BrTCP15 locus was transferred to Mibuna by introgression. Furthermore, we conducted a survey of ancient literature to reveal the divergence of Mibuna and found that hybridization between Mizuna and a simple-leaved turnip might have occurred in the past. Indeed, the genomic analysis of multiple turnip cultivars showed that one of the cultivars, Murasakihime, has almost the same sequence in the BrTCP15 region as Mibuna. These results suggest that the hybridization between Mizuna and turnip has resulted in the establishment of Mibuna.