Folate Biofortification in Hydroponically Cultivated Spinach by the Addition of Phenylalanine

Abstract

Folate is an important vitamin mainly ingested from vegetables, and folate deficiency causes various health problems. Recently, several studies demonstrated folate biofortification in plants or food crops by metabolic engineering through genetic modifications. However, the production and sales of genetically modified foods are under strict regulation. Here, we developed a new approach to achieve folate biofortification in spinach (Spinacia oleracea) without genetic modification. We hydroponically cultivated spinach with the addition of three candidate compounds expected to fortify folate. As a result of liquid chromatography tandem mass spectrometry analysis, we found that the addition of phenylalanine increased the folate content up to 2.0-fold (306 μg in 100 g of fresh spinach), representing 76.5% of the recommended daily allowance for adults. By measuring the intermediates of folate biosynthesis, we revealed that phenylalanine activated folate biosynthesis in spinach by increasing the levels of pteridine and p-aminobenzoic acid. Our approach is a promising and practical approach to cultivate nutrient-enriched vegetables.

Detection of betacyanin in red-tube spinach (Spinacia oleracea) and its biofortification by strategic hydroponics

“…To investigate whether the betacyanin content of red-tube spinach could be biofortified, three candidate compounds that were expected to increase the amount of betacyanins were added to the hydroponic culture system: dopamine, which is a precursor of 2-decarboxybetanin ( Fig 1B ) [ 18 ] and the supply of which increases the demand for betalamic acid, resulting in activation of 2-decarboxybetanin or betanin synthesis [ 19 ]; calcium ions (Ca 2+ ), which are known to be the best abiotic elicitor for increasing betacyanin contents [ 10 ]; and sucrose, which is known to be the best carbohydrate for secondary metabolite production [ 20 ]. We determined the doses of compounds based on these previous studies, and the biofortification schema on our previous study [ 16 ].…”

“…In a previous report, we constructed a hydroponic cultivation system to develop nutritious vegetables by adjusting the composition of liquid fertilizer [ 16 ]. In that study, we successfully produced biofortified spinach with a two-fold greater content of folate by hydroponically cultivating spinach plants in a nutrient solution containing phenylalanine [ 16 ].…”

“…In a previous report, we constructed a hydroponic cultivation system to develop nutritious vegetables by adjusting the composition of liquid fertilizer [ 16 ]. In that study, we successfully produced biofortified spinach with a two-fold greater content of folate by hydroponically cultivating spinach plants in a nutrient solution containing phenylalanine [ 16 ]. This approach has the advantages of not involving genetic modification, meaning that circulation of the resultant biofortified vegetables will not be restricted in the market, as well as being easy to perform at a reasonable cost through the use of inexpensive compounds.…”

“…In this study, we detected the production of betacyanins in red-tube spinach ( Spinacia orelacea L.) and aimed to develop a novel method for biofortifying the betacyanin content of red-tube spinach ( Spinacia orelacea L.) through hydroponic cultivation to examine the broader applicability of our recently developed biofortification method [ 16 ] and to improve our understanding of the mechanism of betacyanin biosynthesis.…”

Scalable Treatment of Flowing Organic Liquids Using Ambient-Air Glow Discharge for Agricultural Applications

“…L -Phenylalanine ( L -Phe, C 9 H 11 NO 2 ) is a commonly used component of amino acid fertilizers; it was reported that use of L -Phe allows the production of tropane alkaloids to increase (up to industrial scale) as a secondary plant metabolite, and achieve folate (which is an important vitamin) biofortification in vegetables [27][28][29][30]. On the other hand, pathogenic bacterial presence in a hydroponic nutrient solution could interfere with plant growth and contaminate the collected crops; therefore, a bactericidal effect of the nutrient solution is desired [31].…”