Southwest Forestry University, Kunming, 650224, Yunnan, China.
Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.
Plant Cell Rep. 2022 Aug;41(8):1751-1761. doi: 10.1007/s00299-022-02889-4. Epub 2022 Jun 24.
Ketocarotenoids were synthesized successfully in Camelina sativa seeds by genetic modification without using a traditional selection marker genes. This method provided an interesting tool for metabolic engineering of seed crops. Camelina sativa (L.) Crantz is an important oil crop with many excellent agronomic traits. This model oil plant has been exploited to accumulate value-added bioproducts using genetic manipulation that depends on antibiotic- or herbicide-based selection marker genes (SMG), one of the major concerns for genetically modified foods. Here we reported metabolic engineering of C. sativa to synthesize red ketocarotenoids that could serve as a reporter to visualize transgenic events without using a traditional SMG. Overexpression of a non-native β-carotene ketolase gene coupled with three other carotenogenous genes (phytoene synthase, β-carotene hydroxylase, and Orange) in C. sativa resulted in production of red seeds that were visibly distinguishable from the normal yellow ones. Constitutive expression of the transgenes led to delayed plant development and seed germination. In contrast, seed-specific transformants demonstrated normal growth and seed germination despite the accumulation of up to 70-fold the level of carotenoids in the seeds compared to the controls, including significant amounts of astaxanthin and keto-lutein. As a result, the transgenic seed oils exhibited much higher antioxidant activity. No significant changes were found in the profiles of fatty acids between transgenic and control seeds. This study provided an interesting tool for metabolic engineering of seed crops without using a disputed SMG.
角鲨烯在荠蓝种子中通过遗传修饰成功合成，而不使用传统的选择标记基因。这种方法为种子作物的代谢工程提供了一个有趣的工具。荠蓝（L.）Crantz 是一种重要的油料作物，具有许多优良的农艺性状。这种模式油料植物已被用于通过遗传操作来积累增值的生物制品，这种遗传操作依赖于抗生素或除草剂为基础的选择标记基因（SMG），这是对转基因食品的主要关注之一。在这里，我们报道了荠蓝的代谢工程，以合成红色角鲨烯，作为一种无需使用传统 SMG 即可可视化转基因事件的报告基因。非天然β-胡萝卜素酮化酶基因的过表达与另外三个类胡萝卜素生物合成基因（phytoene synthase、β-carotene hydroxylase 和 Orange）在荠蓝中的共表达导致红色种子的产生，这些红色种子与正常的黄色种子明显不同。转基因的组成型表达导致植物发育和种子萌发延迟。相比之下，种子特异性转化体尽管在种子中积累了高达 70 倍的类胡萝卜素水平，包括大量的虾青素和酮叶黄素，但仍表现出正常的生长和种子萌发。因此，转基因种子油表现出更高的抗氧化活性。在转基因和对照种子之间，脂肪酸的图谱没有发现明显的变化。这项研究为不使用有争议的 SMG 进行种子作物的代谢工程提供了一个有趣的工具。
