Folate Biofortification in Hydroponically Cultivated Spinach by the Addition of Phenylalanine

A decade of improving nutritional quality of horticultural crops agronomically (2012-2022): A systematic literature review

The ultimate goal of world crop production is to produce more with less to meet the growing population demands. However, concentrating solely on increased quantity of production often impacts the quality of produce. Consumption of crops or foods that do not meet nutritional or dietary needs can lead to malnutrition. Malnutrition and undernutrition are prevalent in a significant portion of the population. Agronomic biofortification of minerals and vitamins in horticultural crops has emerged as a promising approach to address nutrient deficiencies and enhance the nutritional quality of food. Despite numerous research papers on plant nutrient biofortification, there remains a lack of systematic reviews that comprehensively summarize the latest knowledge on this topic. Herein we discuss different agronomic ways to biofortify several horticultural crops over the past decade. This systematic review aims to fill this gap by presenting various methodologies and comparing the outcomes of these methods in respect to nutrient content in plant parts. The review focuses on original research papers collected from various scientific databases including Scopus and Web of Knowledge, covering the most recent literature from the last ten years (2012-2022) for specific studies on the agronomic biofortification macronutrients, micronutrients, and vitamins in horticultural plants with exclusion of certain criteria such as 'genetic,' 'breeding,' and 'agronomic crops.' This review critically analyzes the current state of research and explores prospects for the future in this field. The biofortification of various minerals and vitamins, including calcium, selenium, iodine, B vitamins, vitamin A, and vitamin C, are examined, highlighting the achievements and limitations of existing studies. In conclusion, agronomic biofortification of minerals and vitamins in horticultural crops with further research offers a promising approach to address nutrient deficiencies and improve the nutritional quality of food.

Metabolic profiling and transcriptome analysis provide insights into the accumulation of flavonoids in chayote fruit during storage

Chayote (Sechium edulel) fruits are rich in flavonoids, folate, and low-calorie food. However, studies about the flavonoids and the corresponding regulatory mechanism of flavonoid synthesis in chayote fruits was still unclear. In present study, an integrated transcriptome and metabolite analysis of chayote fruits at three different storage stages were conducted to explore the flavonoid compositions and gene expression associated with flavonoid synthesis. Through the UPLC-MS/MS analysis, a total of 57 flavonoid compounds were detected. Of these, 42 flavonoid glycosides were significantly differential accumulation in chayote fruits at three different storage stages. Many genes associated with flavonoid synthesis were differentially expressed in chayote fruits at three different storage stages through RNA-seq analysis, including structural genes and some TFs. There was a high correlation between RNA-seq analysis and metabolite profiling, and the expression level of candidate genes in the flavonoid synthesis pathway were consistent with the dynamic changes of flavonoids. In addition, one R2R3-MYB transcription factor, FSG0057100, was defined as the critical regulatory gene of flavonoid synthesis. Furthermore, exogenous application of phenylalanine increased the total content of flavonoids and promoted some flavonoid biosynthesis-related gene expression in chayote fruits. The above results not only make us better understand the molecular mechanism of flavonoid synthesis in chayote fruits, but also contribute to the promotion and application of chayote products.

Current Status and Potential of Biofortification to Enhance Crop Nutritional Quality: An Overview

Around 2 billion people are suffering from chronic malnutrition or “hidden hunger”, which is the result of many diseases and disorders, including cognitive degeneration, stunting growth, and mortality. Thus, biofortification of staple food crops enriched with micronutrients is a more sustainable option for providing nutritional supplements and managing malnutrition in a society. Since 2001, when the concept of biofortification came to light, different research activities have been carried out, like the development of target populations, breeding or genetic engineering, and the release of biofortified cultivars, in addition to conducting nutritional efficacy trials and delivery plan development. Although, being a cost-effective intervention, it still faces many challenges, like easy accessibility of biofortified cultivars, stakeholders’ acceptance, and the availability of biofortified germplasm in the public domain, which varies from region to region. Hence, this review is focused on the recent potential, efforts made to crop biofortification, impacts analysis on human health, cost-effectiveness, and future perspectives to further strengthen biofortification programs. Through regular interventions of sustainable techniques and methodologies, biofortification holds huge potential to solve the malnutrition problem through regular interventions of nutrient-enriched staple food options for billions of people globally.

Red light enhances folate accumulation in wheat seedlings

Red, white, blue, green, and yellow lights were applied to investigate their effects on folate accumulation in wheat seedlings. The different lights, especially red light, significantly increased the total folate content. Total folate showed maximum accumulation under 30 μmol/(m²·s) of red light, with an increase of 24% compared with the control (darkness). 5-Methyl-tetrahydrofolate (5-CH₃-THF) was the dominant folate component, and was significantly increased by red light irradiation. In addition, under red light, the folate content of leaves was higher and more sensitive to light than that of endosperm or roots. Red light up-regulated the expression of guanosine triphosphate (GTP) cyclohydrolase 1 (GCH1) and aminodeoxychorismate synthase(ADCS), enhanced the activity of GCH1 and ADCS, and increased the content of precursors of folate synthesis, including pterin and p-aminobenzoic acid (pABA). Hence, the increased folate accumulation promoted by light could be attributed to the increased content of folate synthesis precursors, the activity of key enzymes, and related gene expression.

Vitamin B12 (Cobalamin) and Micronutrient Fortification in Food Crops Using Nanoparticle Technology

It is necessary to develop a resilient food supply that will withstand unexpected future shocks and deliver the required amounts of nutrients to consumers. By increasing the sustainability of food and agriculture, the food system will be able to handle challenges such as climate change, declining agricultural resources, growing population/urbanization, pandemics, and recessions/shortages. Micronutrient deficiency, otherwise called hidden hunger, is one of the major malnutrition consequences worldwide, particularly in middle- or low- income countries. Unlike essential mineral or nutrient compounds, micronutrients could be less of a priority due to their small levels of requirement. However, insufficient micronutrients caused critical adverse health symptoms and are excessively vital for young children's development. Therefore, there have been numerous attempts to enhance minerals and nutrients in food crops, including biofortification, food fortification, and supplementation. Based on several interventions involving micronutrients, modern technology, such as nanotechnology, can be applied to enhance sustainability and to reduce the food system's environmental impact. Previous studies have addressed various strategies or interventions to mitigate major micronutrient deficiency including iron, iodine, zinc, and vitamin A. Comparably small amounts of studies have addressed vitamin B12 deficiency and its fortification in food crops. Vitamin B12 deficiency causes serious adverse health effects, including in the nervous or blood systems, and occurs along with other micronutrient deficiencies, such as folate, iron, and zinc, worldwide, particularly in middle- and low-income countries. Mitigation for B12 deficiency has mainly focused on developing pharmacological and medical treatments such as vitamin B12 serum or supplements. Further studies are required to undertake a sustainable approach to fortify vitamin B12 in plant-based food sources for public health worldwide. This review paper highlights nanoparticle application as a promising technology for enhancing vitamin B12 without conventional genetic modification requirements. The nanoparticle can efficiently deliver the mineral/nutrient using coating techniques to targeted sites into the plant. This is mainly because nanoparticles have better solubility and permeability due to their nano size with high surface exposure. Vitamin B12-coated nanoparticles would be absorbed, translocated, and accumulated by the plant and eventually enhance the bioavailability in food crops. Furthermore, by reducing adverse environmental effects, such as leaching issues that mainly occur with conventional fertilizer usage, it would be possible to develop more sustainable food fortification.

Fluorescent paper-based sensor based on carbon dots for detection of folic acid

Paper-based devices have been very much in the foreground of analytical science recently. This work innovatively proposed a fluorescent paper-based sensor (FPS) constructed on a hybrid polydimethylsiloxane (PDMS)/paper platform where cellulose papers functionalized with carbon dots (CDs) as fluorophores by Schiff base chemistry were loaded on the grooves array of a designed PDMS plate. As a proof of concept, the performance of FPS was investigated with folic acid (FA) as the target analyte. Under optimal conditions, FPS enabled a rapid fluorescence quenching response to FA via inner filter effect in a wide range of 1-300 μmol L^-1 with the limit of detection of 0.28 μmol L^-1. The feasibility of FPS was further verified by the detection of FA in orange juice and urine samples with satisfactory results. The covalent modification of CDs on paper endowed the FPS with good assay reproducibility and stability. Interestingly, FPS achieved a more sensitive assay of FA than the conventional strategy, by which the same CDs were directly used to detect FA in a solution-based system. The FPS illuminated a novel strategy for construction of reliable and sensitive assays based on paper-based devices. It is of paramount importance for its practical application in biosensing and clinical diagnosis. Graphical abstract.

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

In this work, we developed a portable device with low production and operation costs for generating ambient-air glow discharge (AAGD) that is transferred to the surface of flowing liquid and demonstrated its applicability to practical use in agriculture. An experiment procedure that ensured the stable treatment of various liquids was established. Additionally, it was found that humidity did not have a significant effect on the treatment process, which makes the use of the developed device possible in various locations. It was found that an L-phenylalanine solution treated with AAGD allows simultaneous 40% hydroponic radish-sprout growth promotion with a bactericidal effect. Further, scalability and practical-application possibilities in hydroponic plant growth were discussed.

From Central to Specialized Metabolism: An Overview of Some Secondary Compounds Derived From the Primary Metabolism for Their Role in Conferring Nutritional and Organoleptic Characteristics to Fruit

Fruit flavor and nutritional characteristics are key quality traits and ones of the main factors influencing consumer preference. Central carbon metabolism, also known as primary metabolism, contributes to the synthesis of intermediate compounds that act as precursors for plant secondary metabolism. Specific and specialized metabolic pathways that evolved from primary metabolism play a key role in the plant's interaction with its environment. In particular, secondary metabolites present in the fruit serve to increase its attractiveness to seed dispersers and to protect it against biotic and abiotic stresses. As a consequence, several important organoleptic characteristics, such as aroma, color, and fruit nutritional value, rely upon secondary metabolite content. Phenolic and terpenoid compounds are large and diverse classes of secondary metabolites that contribute to fruit quality and have their origin in primary metabolic pathways, while the delicate aroma of ripe fruits is formed by a unique combination of hundreds of volatiles that are derived from primary metabolites. In this review, we show that the manipulation of primary metabolism is a powerful tool to engineer quality traits in fruits, such as the phenolic, terpenoid, and volatile content. The enzymatic reactions responsible for the accumulation of primary precursors are bottlenecks in the transfer of metabolic flux from central to specialized metabolism and should be taken into account to increase the yield of the final products of the biosynthetic pathways. In addition, understanding the connection and regulation of the carbon flow between primary and secondary metabolism is a key factor for the development of fruit cultivars with enhanced organoleptic and nutritional traits.

From in planta Function to Vitamin-Rich Food Crops: The ACE of Biofortification

Humans are highly dependent on plants to reach their dietary requirements, as plant products contribute both to energy and essential nutrients. For many decades, plant breeders have been able to gradually increase yields of several staple crops, thereby alleviating nutritional needs with varying degrees of success. However, many staple crops such as rice, wheat and corn, although delivering sufficient calories, fail to satisfy micronutrient demands, causing the so called 'hidden hunger.' Biofortification, the process of augmenting nutritional quality of food through the use of agricultural methodologies, is a pivotal asset in the fight against micronutrient malnutrition, mainly due to vitamin and mineral deficiencies. Several technical advances have led to recent breakthroughs. Nutritional genomics has come to fruition based on marker-assisted breeding enabling rapid identification of micronutrient related quantitative trait loci (QTL) in the germplasm of interest. As a complement to these breeding techniques, metabolic engineering approaches, relying on a continuously growing fundamental knowledge of plant metabolism, are able to overcome some of the inevitable pitfalls of breeding. Alteration of micronutrient levels does also require fundamental knowledge about their role and influence on plant growth and development. This review focuses on our knowledge about provitamin A (beta-carotene), vitamin C (ascorbate) and the vitamin E group (tocochromanols). We begin by providing an overview of the functions of these vitamins in planta, followed by highlighting some of the achievements in the nutritional enhancement of food crops via conventional breeding and genetic modification, concluding with an evaluation of the need for such biofortification interventions. The review further elaborates on the vast potential of creating nutritionally enhanced crops through multi-pathway engineering and the synergistic potential of conventional breeding in combination with genetic engineering, including the impact of novel genome editing technologies.

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

Betacyanins have been reported as water-soluble, nitrogenous pigments found in the order Caryophyllales, and they are known for powerful natural antioxidant. The biofortification of secondary metabolites such as anthocyanins and betacyanins has recently been performed in food crops by metabolic engineering through genetic modification. However, the distribution of genetically modified foods is strictly regulated. Therefore, we aimed to develop a new method for biofortifying natural antioxidants, betacyanins, without genetic modification. We first detected the presence of betacyanins in red-tube spinach (Spinacia oleracea) through ultraviolet-visible spectroscopy and mass spectrometry. We then hydroponically cultivated plants in the presence of three candidate compounds for betacyanin biofortification: dopamine, Ca2+, and sucrose. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and antioxidant activity analyses showed that sucrose was most successful in biofortifying betacyanins, and reverse transcription polymerase chain reaction (RT-PCR) indicated that several genes involved in betacyanin biosynthesis were induced by sucrose. Therefore, strategic hydroponics represents a new approach for cultivating betacyanin-enriched vegetables.

Toward Eradication of B-Vitamin Deficiencies: Considerations for Crop Biofortification

'Hidden hunger' involves insufficient intake of micronutrients and is estimated to affect over two billion people on a global scale. Malnutrition of vitamins and minerals is known to cause an alarming number of casualties, even in the developed world. Many staple crops, although serving as the main dietary component for large population groups, deliver inadequate amounts of micronutrients. Biofortification, the augmentation of natural micronutrient levels in crop products through breeding or genetic engineering, is a pivotal tool in the fight against micronutrient malnutrition (MNM). Although these approaches have shown to be successful in several species, a more extensive knowledge of plant metabolism and function of these micronutrients is required to refine and improve biofortification strategies. This review focuses on the relevant B-vitamins (B1, B6, and B9). First, the role of these vitamins in plant physiology is elaborated, as well their biosynthesis. Second, the rationale behind vitamin biofortification is illustrated in view of pathophysiology and epidemiology of the deficiency. Furthermore, advances in biofortification, via metabolic engineering or breeding, are presented. Finally, considerations on B-vitamin multi-biofortified crops are raised, comprising the possible interplay of these vitamins in planta.