Effect of Amino Acids on Folates Accumulation in Wheat Seedlings during Germination under Red Light Radiation

Abstract

Deficiency of folates can cause various health problems, and germination is a potential way to enrich folates in grain-based food materials. In the present study, the effects of six amino acids (phenylalanine, tyrosine, tryptophan, glutamate, γ-aminobutyric acid, and p-aminobenzoic acid) on folate accumulation during wheat germination under red light radiation were investigated, and an optimized combination of amino acids for promoting folate enrichment was established. The results showed that applying phenylalanine, tyrosine, tryptophan, glutamate, or p-aminobenzoic acid to wheat seedlings during germination can significantly increase the content of total folates through activating the synthesis of the precursors for folate synthesis (pterin and p-aminobenzoic acid) or condensation of these two moieties. Meanwhile, up-regulation of corresponding genes was observed by measuring their expressions to investigate the mechanism for promoting the accumulation of folates. The highest content of folates (ca. 417 µg/100 g DW) was observed when the germinated wheat was cultured with a mixture of 1.5 mM phenylalanine, 0.5 mM tyrosine, 0.5 mM tryptophan, 0.75 mM p-aminobenzoic acid, and 0.5 mM glutamic acid, which was 50% higher than the control seedlings. This study established a promising and practical approach to enhance the accumulation of folates in wheat seedlings.

Transcriptome Analysis Reveals the Mechanisms of Accumulation and Conversion of Folate Derivatives during Germination of Quinoa (Chenopodium quinoa Willd.) Seeds

“…THF, 5-CH 3 -THF, and 10-CHO-THF can be oxidized into FA, MeFox, and 10-CHO-FA, respectively . MeFox has also been found in raw legumes such as soybeans, lentils, chickpeas, and peas and cereals like wheat germ and oat flour . Similarly, our present study found that the content of MeFox was quite high.…”

“…31 MeFox has also been found in raw legumes such as soybeans, lentils, chickpeas, and peas 30 and cereals like wheat germ and oat flour. 18 Similarly, our present study found that the content of MeFox was quite high. As shown in Figure 1B(g,h), in quinoa seeds of LL-1, QL-2, and GZ-4, the ratios of the oxidation product MeFox to 5-CH 3 -THF were 329.5, 122.9, and 226.5%, respectively, while the proportion of MeFox to 5-CH 3 -THF decreased to 33.6, 20.2, and 51.1% in 6-day-old quinoa sprouts of LL-1, QL-2, and GZ-4, respectively.…”

“…Besides, the ratio of oxidation product MeFox to 5-CH 3 -THF significantly decreased, even though the net content of MeFox increased during quinoa seed germination. The antioxidants in the food matrix can protect folate against oxidation, resulting in reduced content of oxidized product MeFox . Moreover, the content of antioxidants in quinoa sprouts significantly increased along with the prolonged germination period, including vitamin C, total phenols, total flavonoids, and carotenoids .…”

“…16 Furthermore, the addition of exogenous Phe and Try promoted the synthesis of p-ABA through upregulating ADCS, which might be owing to the negative feedback on the synthesis of endogenous aromatic amino acids, culminating in the conversion of chorismate to p-ABA. 18 Generally, the enrichment of 5-CH 3 -THF was most pronounced in legumes and cereal sprouts, while 5-CH 3 -THF can be oxidized into pyrazino-s-triazine (MeFox) in numerous food matrices at even higher levels but reduced biological activity. 19 Interestingly, legumes, cereals, pseudocereal, and sprouts showed overall increased antioxidant activity with dramatically raised content of polyphenols, flavonoids, and carotenoids, 15,20 which might protect against the oxidative loss of 5-CH 3 -THF and 5-CHO-THF.…”

“…Chang et al reported that folate accumulation promoted by red light could be attributed to the elevated expression of GCHI and ADCS, enhanced activity of GCHI and ADCS, and increased quantity of folate synthesis precursors pterin and p -ABA . Furthermore, the addition of exogenous Phe and Try promoted the synthesis of p -ABA through upregulating ADCS, which might be owing to the negative feedback on the synthesis of endogenous aromatic amino acids, culminating in the conversion of chorismate to p -ABA . Generally, the enrichment of 5-CH 3 -THF was most pronounced in legumes and cereal sprouts, while 5-CH 3 -THF can be oxidized into pyrazino-s-triazine (MeFox) in numerous food matrices at even higher levels but reduced biological activity .…”