School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia.
Centre for Tropical Crops and Biocommodities, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4001, Australia.
Int J Mol Sci. 2020 Mar 5;21(5):1790. doi: 10.3390/ijms21051790.
Abiotic stresses, such as drought, salinity, and extreme temperatures, are major limiting factors in global crop productivity and are predicted to be exacerbated by climate change. The overproduction of reactive oxygen species (ROS) is a common consequence of many abiotic stresses. Ascorbate, also known as vitamin C, is the most abundant water-soluble antioxidant in plant cells and can combat oxidative stress directly as a ROS scavenger, or through the ascorbate-glutathione cycle-a major antioxidant system in plant cells. Engineering crops with enhanced ascorbate concentrations therefore has the potential to promote broad abiotic stress tolerance. Three distinct strategies have been utilized to increase ascorbate concentrations in plants: (i) increased biosynthesis, (ii) enhanced recycling, or (iii) modulating regulatory factors. Here, we review the genetic pathways underlying ascorbate biosynthesis, recycling, and regulation in plants, including a summary of all metabolic engineering strategies utilized to date to increase ascorbate concentrations in model and crop species. We then highlight transgene-free strategies utilizing genome editing tools to increase ascorbate concentrations in crops, such as editing the highly conserved upstream open reading frame that controls translation of the gene.
非生物胁迫，如干旱、盐度和极端温度，是全球作物生产力的主要限制因素，并预计会因气候变化而加剧。活性氧（ROS）的过度产生是许多非生物胁迫的常见后果。抗坏血酸，也称为维生素 C，是植物细胞中含量最丰富的水溶性抗氧化剂，可直接作为 ROS 清除剂来抵抗氧化应激，或通过抗坏血酸-谷胱甘肽循环——植物细胞中的主要抗氧化系统。因此，工程作物中增强的抗坏血酸浓度有可能促进广泛的非生物胁迫耐受性。已经利用了三种不同的策略来增加植物中的抗坏血酸浓度：（i）增加生物合成，（ii）增强循环，或（iii）调节调节因子。在这里，我们回顾了植物中抗坏血酸生物合成、循环和调节的遗传途径，包括迄今为止用于增加模型和作物物种中抗坏血酸浓度的所有代谢工程策略的摘要。然后，我们强调了利用基因组编辑工具增加作物中抗坏血酸浓度的无转基因策略，例如编辑控制 基因翻译的高度保守上游开放阅读框。
