Biofortification of plants with altered antioxidant content and composition: genetic engineering strategies

Abstract

email christou@pvcf.udl.es) † These authors contributed equally to this work.Keywords: biofortification, antioxidants, genetic engineering. SummaryAntioxidants are protective molecules that neutralize reactive oxygen species and prevent oxidative damage to cellular components such as membranes, proteins and nucleic acids, therefore reducing the rate of cell death and hence the effects of ageing and ageing-related diseases. The fortification of food with antioxidants represents an overlap between two diverse environments, namely fortification of staple foods with essential nutrients that happen to have antioxidant properties (e.g. vitamins C and E) and the fortification of luxury foods with healthpromoting but non-essential antioxidants such as flavonoids as part of the nutraceuticals/ functional foods industry. Although processed foods can be artificially fortified with vitamins, minerals and nutraceuticals, a more sustainable approach is to introduce the traits for such health-promoting compounds at source, an approach known as biofortification. Regardless of the target compound, the same challenges arise when considering the biofortification of plants with antioxidants, that is the need to modulate endogenous metabolic pathways to increase the production of specific antioxidants without affecting plant growth and development and without collateral effects on other metabolic pathways. These challenges become even more intricate as we move from the engineering of individual pathways to several pathways simultaneously. In this review, we consider the state of the art in antioxidant biofortification and discuss the challenges that remain to be overcome in the development of nutritionally complete and health-promoting functional foods.

Elevated vitamin E content improves all- trans β-carotene accumulation and stability in biofortified sorghum

“…To gain insight into all-trans β-carotene accumulation throughout seed development, we determined the accumulation of PSY1 protein (the enzyme that controls the rate-limiting step of carotenoid biosynthesis) by LC-MS/MS at six stages of seed development (10,17,24,30,38, and 45 DAP) in event ABS203-4. We found that PSY1 accumulated to the highest levels at the milkstage (around 17 DAP) and declined sharply to an undetected level at maturity (around 45 DAP) (Fig.…”

“…Although sorghum is gluten-free and could be an attractive replacement for wheat-allergy sufferers, it is considered a nutrient-poor crop (8, 9) with very low amounts of β-carotene (10). The improvement of micronutrients in food crops has attracted considerable attention, and significant advances have been made in a range of major crops (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Nutritional improvement in sorghum was undertaken a decade ago (23, 24); however, progress has lagged behind the progress in other crops.…”

Can biofortification of zinc improve the antioxidant capacity and nutritional quality of beans?

“…Yuan et al (2016) studied the result of enrichment of zinc on antioxidant capacity and growth in pea sprouts and found an increase from 10 to 50 µM Zinc improved antioxidant capacity due in turn to increase the Zn content, chlorophylls, phenolic content and amino acids, Zn enrichment could increase the nutritional quality and antioxidant activity as functional foods. Previous studies showed that the antioxidant capacity may depend on the abundance of metal ions (Zhu et al 2013). This means that certain metals are required in small quantities by humans and they act as cofactors of enzymes, transcription factors and signaling proteins.…”

Antioxidant content and cytological examination of aqueous fluid from patients with age-related cataracts at different stages

“…Aqueous fluid antioxidants decrease significantly with increasing lenticular nucleus hardness, and reach a minimum at hardness Level V, at which point an ultrasonic emulsification operation is unsuitable (Bonaccio et al, 2013;Zhu et al, 2013).…”

“…Large amounts of reactive oxygen species accumulate in the aqueous fluid and lenses with age; they cause SOD and GSH-PX consumption, changing the soluble proteins in the lens into insoluble proteins, which results in lens opacity (Lu and Rasco, 2012;Gupta and Ahmad, 2013). Reduced CAT weakens the antioxidant capacity of the lens epithelial cells and induces their apoptosis, which also causes cataracts (Ravipati et al, 2012;Zhu et al, 2013).…”