Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, China.
Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, The Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212100, China.
Proc Natl Acad Sci U S A. 2023 Aug 15;120(33):e2306322120. doi: 10.1073/pnas.2306322120. Epub 2023 Aug 7.
Plants produce various pigments that not only appear as attractive colors but also provide valuable resources in applications in daily life and scientific research. Biosynthesis pathways for these natural plant pigments are well studied, and most have multiple enzymes that vary among plant species. However, adapting these pathways to animals remains a challenge. Here, we describe successful biosynthesis of betalains, water-soluble pigments found only in a single plant order, Caryophyllales, in transgenic silkworms by coexpressing three betalain synthesis genes, cytochrome P450 enzyme , and . Betalains can be synthesized in various tissues under the control of the ubiquitous IE1 promoter but accumulate mainly in the hemolymph with yields as high as 274 μg/ml. Additionally, transformed larvae and pupae show a strong red color easily distinguishable from wild-type animals. In experiments in which expression is controlled by the promoter of silk gland-specific gene, , betalains are found predominantly in the silk glands and can be secreted into cocoons through spinning. Betalains in transformed cocoons are easily recovered from cocoon shells in water with average yields reaching 14.4 μg/mg. These data provide evidence that insects can synthesize natural plant pigments through a complex, multiple enzyme-mediated synthesis pathway. Such pigments also can serve as dominant visible markers in insect transgenesis applications. This study provides an approach to producing valuable plant-derived compounds by using genetically engineered silkworms as a bioreactor.
植物产生各种色素，这些色素不仅呈现出吸引人的颜色，而且在日常生活和科学研究的应用中提供有价值的资源。这些天然植物色素的生物合成途径已经得到了很好的研究，并且大多数都有多种在植物物种之间变化的酶。然而，将这些途径适应于动物仍然是一个挑战。在这里，我们通过共表达三种甜菜红素合成基因、细胞色素 P450 酶和，成功地在转基因家蚕中合成了仅在单一植物目石竹目中发现的水溶性色素甜菜红素。甜菜红素可以在广泛表达的 IE1 启动子的控制下在各种组织中合成，但主要在血液中积累，产量高达 274μg/ml。此外，转化的幼虫和蛹呈现出强烈的红色，很容易与野生型动物区分开来。在通过丝腺特异性基因的启动子控制表达的实验中，甜菜红素主要存在于丝腺中，并可以通过纺丝分泌到茧中。通过在水中从茧壳中容易回收转化茧中的甜菜红素，平均产量达到 14.4μg/mg。这些数据表明昆虫可以通过复杂的、多酶介导的合成途径合成天然植物色素。这些色素也可以作为昆虫转基因应用中的显性可见标记。本研究为利用基因工程家蚕作为生物反应器生产有价值的植物衍生化合物提供了一种方法。
