Tomizawa Eri, Ohtomo Shogo, Asai Kanako, Ohta Yuka, Takiue Yukako, Hasumi Akihiro, Nishihara Masahiro, Nakatsuka Takashi
Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Shizuoka 422-8529, Japan.
Faculty of Agriculture, Shizuoka University, Shizuoka, Shizuoka 422-8529, Japan.
Plant Biotechnol (Tokyo). 2021 Sep 25;38(3):323-330. doi: 10.5511/plantbiotechnology.21.0516a.
Betalains, comprising violet betacyanins and yellow betaxanthins, are pigments found in plants belonging to the order Caryophyllales. In this study, we induced the accumulation of betalains in ornamental lisianthus () by genetic engineering. Three betalain biosynthetic genes encoding CYP76AD1, dihydroxyphenylalanine (DOPA) 4,5-dioxygenase (DOD), and -DOPA 5--glucosyltransferase (5GT) were expressed under the control of the cauliflower mosaic virus (CaMV) promoter in lisianthus, in which anthocyanin pigments are responsible for the pink flower color. During the selection process on hygromycin-containing media, some shoots with red leaves were obtained. However, most red-colored shoots were suppressed root induction and incapable of further growth. Only clone #1 successfully acclimatized and bloomed, producing pinkish-red flowers, with a slightly greater intensity of red color than that in wild-type flowers. T plants derived from clone #1 segregated into five typical flower color phenotypes: wine red, bright pink, pale pink, pale yellow, and salmon pink. Among these, line #1-1 showed high expression levels of all three transgenes and exhibited a novel wine-red flower color. In the flower petals of line #1-1, abundant betacyanins and low-level betaxanthins were coexistent with anthocyanins. In other lines, differences in the relative accumulation of betalain and anthocyanin pigments resulted in flower color variations, as described above. Thus, this study is the first to successfully produce novel flower color varieties in ornamental plants by controlling betalain accumulation through genetic engineering.
甜菜色素包括紫色的甜菜青素和黄色的甜菜黄素，是石竹目植物中发现的色素。在本研究中，我们通过基因工程诱导观赏型洋桔梗（）中甜菜色素的积累。编码CYP76AD1、二羟基苯丙氨酸（DOPA）4,5 -双加氧酶（DOD）和β-DOPA 5-O-葡萄糖基转移酶（5GT）的三个甜菜色素生物合成基因在花椰菜花叶病毒（CaMV） 启动子的控制下在洋桔梗中表达，在洋桔梗中花青素色素决定了粉色花朵的颜色。在含潮霉素培养基上的筛选过程中，获得了一些红叶芽。然而，大多数红色芽抑制生根诱导且无法进一步生长。只有克隆#1成功驯化并开花，产生粉红色花朵，红色强度略高于野生型花朵。来自克隆#1的T植株分离出五种典型的花色表型：酒红色、亮粉色、浅粉色、浅黄色和鲑鱼粉色。其中，株系#1-1显示所有三个转基因的高表达水平，并呈现出一种新的酒红色花色。在株系#1-1的花瓣中，丰富的甜菜青素和低水平的甜菜黄素与花青素共存。在其他株系中，如上述，甜菜色素和花青素色素相对积累的差异导致了花色变化。因此，本研究首次通过基因工程控制甜菜色素积累成功地在观赏植物中产生了新的花色品种。
