Metabolic engineering in food crops to enhance ascorbic acid production: crop biofortification perspectives for human health

Abstract

Ascorbic acid (AsA) also known as vitamin C is considered as an essential micronutrient in the diet of humans. The human body is unable to synthesize AsA, thus solely dependent on exogenous sources to accomplish the nutritional requirement. AsA plays a crucial role in different physiological aspects of human health like bone formation, iron absorption, maintenance and development of connective tissues, conversion of cholesterol to bile acid and production of serotonin. It carries antioxidant properties and is involved in curing various clinical disorders such as scurvy, viral infection, neurodegenerative diseases, cardiovascular diseases, anemia, and diabetes. It also plays a significant role in COVID-19 prevention and recovery by improving the oxygen index and enhancing the production of natural killer cells and T-lymphocytes. In plants, AsA plays important role in floral induction, seed germination, senescence, ROS regulation and photosynthesis. AsA is an essential counterpart of the antioxidant system and helps to defend the plants against abiotic and biotic stresses. Surprisingly, the deficiencies of AsA are spreading in both developed and developing countries. The amount of AsA in the major food crops such as wheat, rice, maize, and other raw natural plant foods is inadequate to fulfill its dietary requirements. Hence, the biofortification of AsA in staple crops would be feasible and cost-effective means of delivering AsA to populations that may have limited access to diverse diets and other interventions. In this review, we endeavor to provide information on the role of AsA in plants and human health, and also perused various biotechnological and agronomical approaches for elevating AsA content in food crops.

High-Nitrate-Supply-Induced Transcriptional Upregulation of Ascorbic Acid Biosynthetic and Recycling Pathways in Cucumber

“…In earlier works, growth rate has been associated with AsA, based on external applications leading to accelerated growth [ 29 ]. In transgenic studies, overexpression of AsA biosynthetic enzymes and related regulators provided evidence for the growth-promoting and stress-ameliorative effects of AsA [ 30 ]. Therefore, AsA levels were measured in leaf tissues of both hybrids.…”

Biofortification as a solution for addressing nutrient deficiencies and malnutrition

“…Numerous genes of the l -galactose/ d -mannose pathways have resulted in diverse crops to increase ascorbic acid content, but the results were not satisfactory [ 141 , 142 ]. It has been shown that the countenance of GGP, which characterizes the blockage of ascorbic acid biosynthesis [ 143 ], is a beautiful approach to biofortify vitamin C [ 144 ]. For example, in Arabidopsi s, transient overexpression of the GGP gene results in an increase in ascorbic acid content up to 2.5 times, however; increased expression of the extra genes implicated in the same biosynthetic pathway does not result in significant changes in ascorbic acid content [ 145 ].…”

A multi-response sensor based on a bat-like Zn(II) coordination polymer: synthesis, structure and ‘turn off’ sensing of TC, Fe3+ and AA in aqueous system

“…Among the easily decomposable organics, tetracycline (TC) could be easily degraded by most microorganisms, but the residue can lead to selective variation of microorganisms and the emergence of drug-resistant pathogens [7][8][9]. As a reducing agent, ascorbic acid (AA) is widely used in medicine, food and cosmetics [10]. However, excessive intake would disrupt the normal metabolism of cells, leading to coronary heart disease and urinary calculi [11][12].…”