Amaranth: A New Millennium Crop of Nutraceutical Values

Identification and Characterization of Novel Antioxidant Protein Hydrolysates from Kiwicha (Amaranthus caudatus L.)

Kiwicha (Amaranthus caudatus) is considered one of the few multipurpose pseudocereals for its potential use not only as a source of nutrients and fiber but also for its bioactive compounds. In recent years, antioxidant peptides are commonly used as functional ingredient of food. Herein, a kiwicha protein isolate (KPI), obtained from kiwicha defatted flour (KDF), was hydrolyzed by Bioprotease LA 660, a food-grade endoprotease, under specific conditions. The resulting kiwicha protein hydrolysates (KPHs) were chemically characterized and their digestibility and antioxidant capacity were evaluated by in vitro cell-free experiments owing to their measure of capacity to sequester DPPH free radical and reducing power. KPHs showed higher digestibility and antioxidant capacity than intact proteins into KPI. Therefore, the results shown in this study indicate that KPHs could serve as an adequate source of antioxidant peptides, representing an effective alternative to the generation of functional food.

Unlocking the inherent potential of plant genetic resources: food security and climate adaptation strategy in Fiji and the Pacific

Pacific Island Countries (PICs) are the center of origin and diversity for several root, fruit and nut crops, which are indispensable for food security, rural livelihoods, and cultural identity of local communities. However, declining genetic diversity of traditional food crops and high vulnerability to climate change are major impediments for maintaining agricultural productivity. Limited initiatives to achieve food self-sufficiency and utilization of Plant Genetic Resources (PGR) for enhancing resilience of agro-ecosystems are other serious constraints. This review focuses on the visible and anticipated impacts of climate ge, on major food and tree crops in agriculture and agroforestry systems in the PICs. We argue that crop improvement through plant breeding is a viable strategy to enhance food security and climatic resilience in the region. The exploitation of adaptive traits: abiotic and biotic stress tolerance, yield and nutritional efficiency, is imperative in a world threatened by climatic extremes. However, the insular constraints of Fiji and other small PICs are major limitations for the utilization of PGR through high throughput techniques which are also cost prohibitive. Crop Improvement programs should instead focus on the identification, conservation, documentation and dissemination of information on unique landraces, community seed banks, introduction of new resistant genotypes, and sustaining and enhancing allelic diversity.

Photosynthetic Phenomics of Field- and Greenhouse-Grown Amaranths vs. Sensory and Species Delimits

Consumers hesitate to purchase field-grown shoot-tops of amaranths in Sri Lanka, citing the low-cleanliness making growers focus on greenhouse farming. However, the photosynthetic and growth variations in relation to the organoleptic preference of the greenhouse-grown amaranths in comparison to field-grown counterparts have not been studied. Also, the species delimits of the amaranths in Sri Lanka have not been identified, limiting our ability to interpret species-specific production characteristics. Thus, we assessed the common types of amaranths under greenhouse and field conditions. The photosynthesis was measured using a MultispeQ device of the PhotosynQ phenomic platform, which records chlorophyll fluorescence-based parameters. The shoot-tops were harvested and prepared as dishes according to the typical recipe for amaranths in Sri Lanka. The dishes were subjected to an organoleptic assessment for the parameters color, aroma, bitterness, texture, and overall taste. The differences in plant and the shoot-top biomass were also assessed. The markers atpB-rbcL, matk-trnT, and ITS were used to define the species delimits. The field-grown and greenhouse-grown amaranths exhibited species/cultivar-specific photosynthetic variations. The texture and overall taste of the dishes were different among greenhouse and field-grown material. The tasters preferred the texture and the overall taste of the greenhouse-grown shoot-tops. The greenhouse-grown plants also yielded higher shoot-top harvests compared to field-grown counterparts. Out of the tested markers, ITS defines the delimits of amaranth species. The higher organoleptic preference, the appreciable yield levels, unique photosynthetic patterns of the greenhouse-grown amaranths, and species definitions provide the much-needed platform for clean shoot-top production guaranteeing the highest end-user trust.

A Review of Recent Studies on the Antioxidant Activities of a Third-Millennium Food: Amaranthus spp

Amaranth (Amaranthus spp.) plant commonly refers to the sustainable food crop for the 21st century. The crop has witnessed significant attention in recent years due to its high nutritional value and agronomic advantages. It is a relatively well-balanced cosmopolitan food that is a protector against chronic diseases. Usually, the antioxidant activities of amaranth are held responsible for its defensive behavior. Antioxidant activity of plants, generally, is attributed to their phytochemical compounds. The current interest, however, lies in hydrolysates and bioactive peptides because of their numerous biological functions, including antioxidant effect. While the importance of bioactive peptides has been progressively recognized, an integrated review of recent studies on the antioxidant ability of amaranth species, especially their hydrolysates and peptides has not been generated. Hence, in this review, we summarize studies focused on the antioxidant capacity of amaranth renewal over the period 2015-2020. It starts with a background and overall image of the amaranth-related published reviews. The current research focusing on in vitro, in vivo, and chemical assays-based antioxidant activity of different amaranth species are addressed. Finally, the last segment includes the latest studies concerning free radical scavenging activity and metal chelation capacity of amaranth protein hydrolysates and bioactive peptides.

Identification of genuine and novel miRNAs in Amaranthus hypochondriacus from high-throughput sequencing data

Amaranth has been proposed as an exceptional alternative for food security and climate change mitigation. Information about the distribution, abundance, or specificity of miRNAs in amaranth species is scare. Here, small RNAs from seedlings under control, drought, heat, and cold stress conditions of the Amaranthus hypocondriacus variety "Gabriela" were sequenced and miRNA loci identified in the amaranth genome using the ShortStack software. Fifty-three genuine miRNA clustersthirty-nine belonging to conserved families, and fourteen novel, were identified. Identification of their target genes suggests that conserved amaranth miRNAs are involved in growth and developmental processes, as well as stress responses. MiR0005, an amaranth-specific miRNA, exhibited an unusual high level of expression, akin to that of conserved miRNAs. Overall, our results broaden our knowledge regarding the distribution, abundance and expression of miRNAs in amaranth, providing the basis for future research on miRNAs and their functions in this important species.

Can pseudocereals modulate microbiota by functioning as probiotics or prebiotics?

Amaranth, quinoa, and buckwheat, known as pseudocereals, have been consumed since ancient times and are considered sacred in most cultures. Their grains can be used as cereals for breakfast or mixed with other grains in meals and their health-enhancing effects have been investigated more in recent years. They have an antioxidant effect and their nutrient profiles are enriched with processing techniques such as sprouting and fermentation. Their suitability to different processing techniques and the rapid increase in microbiota researches highlighted the probiotic/prebiotic effects of pseudocereals. Using cultures or naturally fermented amaranth, quinoa and buckwheat exhibited good substrate properties for probiotic bacteria, especially for Lactobacillus strains. Studies have found that they reduce the number of pathogen microorganisms, increase the synthesis of short-chain fatty acids due to their prebiotic effects. Also the number of bacterial colonies do not change during the storage period and their organoleptic properties are revealed. It has been determined that pseudocereals decrease Ruminococcacea, Lachnospiraceae, Helicobacteracea, Clostridium, Escherichia and increase Peptoclostridium, Prevotellaceae, Lactobacillus, Bifidobacterium, Enterococcus, and Eubacteriaceae. Due to these effects, they are considered as good sources for synbiotic formulations to be developed for the treatment of dysbiosis, obesity, Celiac Disease, lactose intolerance, inflammatory bowel diseases and inflammation-mediated chronic disorders.

Defoliation timing for optimal leaf nutrition in dual-use amaranth production systems

BACKGROUND

Amaranth leaves can provide important nutrients to small-scale farming families growing amaranth for seed. Amaranth is known to be tolerant to defoliation, but there is little guidance on when defoliation should be performed for optimal nutritional benefits. This series of experiments assessed tolerance to defoliation at different points throughout the vegetative stage of development, in addition to the nutritional benefits and flavor of amaranth leaves at each stage.

RESULTS

Overall, timing of defoliation had no impact on seed yield or quality. Fifty percent defoliation at any point did not significantly reduce seed yield, whereas 100% defoliation throughout development reduced seed yield. The nutritional value of amaranth leaves differed substantially throughout development, with the highest concentrations of iron mid-way through vegetative development, and the highest levels of vitamin A, magnesium, and copper at the end of the vegetative development stage. Palatability was highest in young leaves, and decreased as plants aged. We also found that neither timing nor intensity of defoliation had an influence on branching, which can negatively influence ease of harvest.

CONCLUSIONS

These results indicate that amaranth leaves are a nutritious food source that provides vital nutrients at different concentrations throughout development. Farmers who wish to harvest both leaves and seeds can harvest up to 50% of the leaves at any point during vegetative development or bud formation while maintaining seed yield. Leaf harvest timing can thus be tailored to nutritional needs, although palatability decreases with plant age. © 2020 Society of Chemical Industry.

Amaranth as a Source of Antihypertensive Peptides

Amaranth is an ancestral crop used by pre-Columbian cultures for 6000 to 8000 years. Its grains have a relevant chemical composition not only from a nutritional point of view but also due to the contribution of components with good techno-functional properties and important potential as bioactive compounds. Numerous studies have shown that amaranth storage proteins possess encrypted sequences that, once released, exhibit different physiological activities. One of the most studied is antihypertensive activity. This review summarizes the progress made over the last years (2008-2020) related to this topic. Studies related to inhibition of different enzymes of the Renin-Angiotensin-Aldosterone system, in particular Angiotensin Converting Enzyme (ACE) and Renin, as well as those referring to potential modulation mechanisms of tissue or local Renin-Angiotensin-Aldosterone system, are analyzed, including in silico, in vitro, in vivo, and ex vivo assays. Furthermore, the potential use of these bioactive peptides or products containing them, in the elaboration of functional food matrices is discussed. Finally, the most relevant conclusions and future requirements in research and development of food products are presented.

Agrobacterium rhizogenes-mediated transformation of grain (Amaranthus hypochondriacus) and leafy (A. hybridus) amaranths

Transgenic A. hypochondriacus and A. hybridus roots were generated. Further, a distinct plant regeneration program via somatic embryos produced from hairy roots was established. Work was implemented to develop an optimized protocol for root genetic transformation of the three grain amaranth species and A. hybridus, their presumed ancestor. Transformation efficiency was species-specific, being higher in A. hypochondriacus and followed by A. hybridus. Amaranthus cruentus and A. caudatus remained recalcitrant. A reliable and efficient Agrobacteruim rhizogenes-mediated transformation of these species was established using cotyledon explants infected with the previously untested BVG strain. Optimal OD₆₀₀ bacterial cell densities were 0.4 and 0.8 for A. hypochondriacus and A. hybridus, respectively. Hairy roots of both amaranth species were validated by the amplification of appropriate marker genes and, when pertinent, by monitoring green fluorescent protein emission or β-glucuronidase activity. Embryogenic calli were generated from A. hypochondriacus rhizoclones. Subsequent somatic embryo maturation and germination required the activation of cytokinin signaling, osmotic stress, red light, and calcium incorporation. A crucial step to ensure the differentiation of germinating somatic embryos into plantlets was their individualization and subcultivation in 5/5 media containing 5% sucrose, 5 g/L gelrite, and 0.2 mg/L 2-isopentenyladenine (2iP) previously acidified to pH 4.0 with phosphoric acid, followed by their transfer to 5/5 + 2iP media supplemented with 100 mg/L CaCl₂. These steps were strictly red light dependent. This process represents a viable protocol for plant regeneration via somatic embryo germination from grain amaranth transgenic hairy roots. Its capacity to overcome the recalcitrance to genetic transformation characteristic of grain amaranth has the potential to significantly advance the knowledge of several unresolved biological aspects of grain amaranths.

The Role of Agrotechnical Factors in Shaping the Protein Yield of Maize (Zea mays L.)

The subject of the work was the evaluation of maize protein yield conditioned by various agrotechnical factors. The test results are derived from two different field experiments covering a total of seven years of observation. Protein yield was significantly dependent on changing weather conditions in the growing seasons. Protein yield was significantly lower in the dry and hot years. The sum of precipitation for the month of May was positively correlated with maize protein yield. However, there was no correlation between the average air temperature and the amount of protein yield. The sum of atmospheric precipitation for the entire growing season (IV–X) shaped maize protein yield in over 96%. A non-linear relationship of the 2nd degree was determined between these traits. Sowing maize into the soil cultivated traditionally (autumn tillage), “stay-green” type cultivars and row fertilization positively influenced maize protein yield. Initial fertilization (regardless of depth) with two-component NP fertilizer, in relation to broadcast fertilization, significantly increased maize protein yield from 11.4% to 18%, respectively. The type of nitrogen fertilizer did not differentiate the value of this trait. Pre-sowing nitrogen application was more effective compared to the top dressing, and significantly increased protein yield. Row fertilization with two-component NP fertilizer clearly affected the content protein in grain. The interdependence of genetic and agronomic progress is an important factor shaping the potential of maize protein yield and cannot be attributed to either breeding (cultivar) or agronomy.

Moisture sorption isotherm and shelf life prediction of complementary food based on amaranth-sorghum grains

The quantity and quality of complementary foods is one of the contributing factors to childhood under nutrition. Complementary food based on amaranth and sorghum grains was formulated. It was deemed to be superior nutritionally to the commonly used complementary foods in Kenya. Knowledge on storage and packaging is important for a long shelf life of the product to be achieved. Water activity and moisture content are key indicators of the stability of dried foods. To establish the proper storage conditions of the product, moisture sorption isotherms at 25 °C, 30 °C and 35 °C were determined over water activity range of 0.11-0.97 and data fitted with six sorption models. Water vapour permeability of common packaging materials was also determined at 25 °C and 35 °C and the data was used to predict the product's shelf life. The product exhibited type two sorption isotherm according to Brunner classification an indication of monolayer-multilayer sorption behavior. The critical storage moisture content of the complementary food corresponding to 0.6 water activity a point of microbiological stability was found to be 7.5%. Based on Heiss-Eichner model, a shelf life of 1423 days at 25 °C can be achieved with product initial moisture content of 5 g/100 g and packaged in 110 µm thick aluminum pouch. The shelf life of the product was shortened two to three fold at 35 °C in comparison to storage at 25 °C.

Healthy and Resilient Cereals and Pseudo-Cereals for Marginal Agriculture: Molecular Advances for Improving Nutrient Bioavailability

With the ever-increasing world population, an extra 1.5 billion mouths need to be fed by 2050 with continuously dwindling arable land. Hence, it is imperative that extra food come from the marginal lands that are expected to be unsuitable for growing major staple crops under the adverse climate change scenario. Crop diversity provides right alternatives for marginal environments to improve food, feed, and nutritional security. Well-adapted and climate-resilient crops will be the best fit for such a scenario to produce seed and biomass. The minor millets are known for their high nutritional profile and better resilience for several abiotic stresses that make them the suitable crops for arid and salt-affected soils and poor-quality waters. Finger millet (Eleucine coracana) and foxtail millet (Setaria italica), also considered as orphan crops, are highly tolerant grass crop species that grow well in marginal and degraded lands of Africa and Asia with better nutritional profile. Another category of grains, called pseudo-cereals, is considered as rich foods because of their protein quality and content, high mineral content, and healthy and balance food quality. Quinoa (Chenopodium quinoa), amaranth (Amaranthus sp.), and buckwheat (Fagopyrum esculentum) fall under this category. Nevertheless, both minor millets and pseudo-cereals are morphologically different, although similar for micronutrient bioavailability, and their grains are gluten-free. The cultivation of these millets can make dry lands productive and ensure future food as well as nutritional security. Although the natural nutrient profile of these crop plant species is remarkably good, little development has occurred in advances in molecular genetics and breeding efforts to improve the bioavailability of nutrients. Recent advances in NGS have enabled the genome and transcriptome sequencing of these millets and pseudo-cereals for the faster development of molecular markers and application in molecular breeding. Genomic information on finger millet (1,196 Mb with 85,243 genes); S. italica, a model small millet (well-annotated draft genome of 420 Mb with 38,801 protein-coding genes); amaranth (466 Mb genome and 23,059 protein-coding genes); buckwheat (genome size of 1.12 Gb with 35,816 annotated genes); and quinoa (genome size of 1.5 Gb containing 54,438 protein-coding genes) could pave the way for the genetic improvement of these grains. These genomic resources are an important first step toward genetic improvement of these crops. This review highlights the current advances and available resources on genomics to improve nutrient bioavailability in these five suitable crops for the sustained healthy livelihood.

Parallel Seed Color Adaptation during Multiple Domestication Attempts of an Ancient New World Grain

Thousands of plants have been selected as crops; yet, only a few are fully domesticated. The lack of adaptation to agroecological environments of many crop plants with few characteristic domestication traits potentially has genetic causes. Here, we investigate the incomplete domestication of an ancient grain from the Americas, amaranth. Although three grain amaranth species have been cultivated as crop for millennia, all three lack key domestication traits. We sequenced 121 crop and wild individuals to investigate the genomic signature of repeated incomplete adaptation. Our analysis shows that grain amaranth has been domesticated three times from a single wild ancestor. One trait that has been selected during domestication in all three grain species is the seed color, which changed from dark seeds to white seeds. We were able to map the genetic control of the seed color adaptation to two genomic regions on chromosomes 3 and 9, employing three independent mapping populations. Within the locus on chromosome 9, we identify an MYB-like transcription factor gene, a known regulator for seed color variation in other plant species. We identify a soft selective sweep in this genomic region in one of the crop species but not in the other two species. The demographic analysis of wild and domesticated amaranths revealed a population bottleneck predating the domestication of grain amaranth. Our results indicate that a reduced level of ancestral genetic variation did not prevent the selection of traits with a simple genetic architecture but may have limited the adaptation of complex domestication traits.

Amaranth as a Dual-Use Crop for Leafy Greens and Seeds: Stable Responses to Leaf Harvest Across Genotypes and Environments

Dual-use production systems that utilize the green leaves as well as seeds from amaranth are highly promising for small-scale farmers around the world. The leaves are an important source of nutrients for farming families, while seeds can provide income. Farmers who use amaranth as a dual-use crop are concerned about the impacts of defoliation on seed yield. This experiment tested defoliation at various intensities and frequencies (0, 25, 50, 75, and 100% defoliation, 1, 2, and 3 times) under controlled conditions as well as under Danish and Mexican field conditions. Defoliation tolerance was tested in a total of seven varieties, spanning the three primary grain amaranth species: A. cruentus, A. hypocondriacus, and A. caudatus. In all of the varieties and environments tested, we found that neither seed yield nor quality was impacted by a single defoliation event at intensities up to 50% leaf removal. We observed similar responses with two and three consecutive defoliations in which we removed 25% of all leaves. Greater frequency and intensity of defoliation resulted in reduced seed yield in some environments, while seed quality (protein content and 1000 KW) did not appear to be affected. Dual-use production systems should be promoted with small-scale farmers around the world as promising systems for improving local nutrition while maintaining profits from seed production. This paper provides baseline guidelines for farmers regarding optimal defoliation intensities and frequencies.

Antioxidant Activity and Phenolic Composition of Amaranth (Amaranthus caudatus) during Plant Growth

The antioxidant activity and phenolic composition of the aerial part of Amaranthus caudatus at seven stages of development were investigated. Total phenolic content, ABTS•+, DPPH•, and O2•- scavenging activity, ferric-reducing antioxidant power (FRAP), and Fe2+ chelating ability were evaluated. The phenolic profile was characterized by 17 compounds. Rutin was predominant in all growth stages, although its content, similar to the quantity of other phenolics, changed during the growth cycle. Flavonols were most abundant in the plants of early flowering and grain fill stages. In contrast, the highest content of hydroxycinnamic acid derivatives was found in the early vegetative stage. The results of antioxidant assays also showed significant differences among plant stages. Generally, the lowest antioxidant activity was found in the shooting and budding stages. Significantly higher activity was observed in amaranths in earlier (vegetative) and later (early flowering and grain fill) stages, suggesting that plants in these stages are valuable sources of antioxidants.

Chemometric analysis of Amaranthus retroflexus in relation to livestock toxicity in southern Australia

Amaranthus retroflexus L., an introduced invasive weed in southern Australia, has been associated with acute renal failure and/or mortality in a number of livestock species. While its leaves, flowers and stems are generally reported to contain high levels of nitrogen, few studies have fully characterised the chemical composition of A. retroflexus foliage with respect to mammalian toxicity. We performed extensive metabolic profiling of stems, leaves, roots and inflorescence tissues of A. retroflexus collected from three spatially and/or temporally distinct toxicity outbreaks, and report on the 1) composition of primary and secondary metabolites in methanolic extracts of A. retroflexus tissues using HPLC and HPLC-MS QToF and 2) chemometric analysis of A. retroflexus extracts in relation to the associated toxin(s). All tissues of A. retroflexus possessed an abundance of N-containing metabolites, particularly quaternary ammonium compounds which were identified as betaines, two of which (valine betaine and isoleucine betaine) are rarely encountered in plants. Cytotoxicity to murine fibroblasts was highest in extracts of leaf tissue and was associated with a single, a small modified peptide with high similarity to N-acetyl-L-α-aspartyl-L-alanyl-L-α-aspartyl-L-α-glutamyl-O-(carboxymethyl)-L-tyrosyl-L-leucinamide, a synthetic phosphotyrosyl mimic involved in cell signaling processes. One possible mode of action leading to acute renal failure in grazing livestock by a modified peptide such as this is proposed.

RNA-sequencing analysis reveals betalains metabolism in the leaf of Amaranthus tricolor L

Amaranth plants contain large amounts of betalains, including betaxanthins and betacyanins. Amaranthin is a betacyanin, and its molecular structure and associated metabolic pathway differ from those of betanin in beet plants. The chlorophyll, carotenoid, betalain, and flavonoid contents in amaranth leaves were analyzed. The abundance of betalain, betacyanin, and betaxanthin was 2-5-fold higher in the red leaf sectors than in the green leaf sectors. Moreover, a transcriptome database was constructed for the red and green sectors of amaranth leaves harvested from 30-day-old seedlings. 22 unigenes were selected to analyze the expression profiles in the two leaf sectors. The RNA-sequencing data indicated that many unigenes are involved in betalain metabolic pathways. The potential relationships between diverse metabolic pathways and betalain metabolism were analyzed. The validation of the expression of 22 selected unigenes in a qRT-PCR assay revealed the genes that were differentially expressed in the two leaf sectors. Betalains were biosynthesized in specific tissues of the red sectors of amaranth leaves. Almost all of the genes related to betalain metabolism were identified in the transcriptome database, and the expression profiles were different between the red sectors and green sectors in the leaf. Amaranth plants consist of diverse metabolic pathways, and the betalain metabolic pathway is linked to a group of other metabolic pathways.

Dietary fiber sources and human benefits: The case study of cereal and pseudocereals

Dietary fiber (DF) includes the remnants of the edible part of plants and analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the human large intestine. DF can be classified into two main groups according to its solubility, namely insoluble dietary fiber (IDF) that mainly consists on cell wall components, including cellulose, some hemicelluloses, lignin and resistant starch, and soluble dietary fiber (SDF) that consists of non-cellulosic polysaccharides as non-digestible oligosaccharides, arabinoxylans (AX), β-glucans, some hemicelluloses, pectins, gums, mucilages and inulin. The intake of DF is associated with health benefits. IDF can contribute to the normal function of the intestinal tract and it has an important role in the prevention of colonic diverticulosis and constipation. SDF is extensively fermented by gut microbiota and it is associated with carbohydrate and lipid metabolism, with important health benefits due to its hypocholesterolemic properties. Due to these nutritional and health properties, DF is widely used as functional ingredients in food industry, being whole grain cereals, pulses, fruits and vegetables the main sources of DF. Also some synthetic sources are employed, namely polydextrose, hydroxypropyl methylcellulose or cyclodextrins. The DF content of cereals varies depending on cultivars, their botanical components (pericarp, emdosperm and germ) and the processing conditions they have undergone (baking, extrusion, etc.). In cereal grains, AX are the predominant non-cellulose DF polysaccharides followed by cellulose and β-glucans, while in pseudocereals, pectins are quantitatively predominant.

Amaranth's 2-Caffeoylisocitric Acid-An Anti-Inflammatory Caffeic Acid Derivative That Impairs NF-κB Signaling in LPS-Challenged RAW 264.7 Macrophages

For centuries, Amaranthus sp. were used as food, ornamentals, and medication. Molecular mechanisms, explaining the health beneficial properties of amaranth, are not yet understood, but have been attributed to secondary metabolites, such as phenolic compounds. One of the most abundant phenolic compounds in amaranth leaves is 2-caffeoylisocitric acid (C-IA) and regarding food occurrence, C-IA is exclusively found in various amaranth species. In the present study, the anti-inflammatory activity of C-IA, chlorogenic acid, and caffeic acid in LPS-challenged macrophages (RAW 264.7) has been investigated and cellular contents of the caffeic acid derivatives (CADs) were quantified in the cells and media. The CADs were quantified in the cell lysates in nanomolar concentrations, indicating a cellular uptake. Treatment of LPS-challenged RAW 264.7 cells with 10 µM of CADs counteracted the LPS effects and led to significantly lower mRNA and protein levels of inducible nitric oxide synthase, tumor necrosis factor alpha, and interleukin 6, by directly decreasing the translocation of the nuclear factor κB/Rel-like containing protein 65 into the nucleus. This work provides new insights into the molecular mechanisms that attribute to amaranth's anti-inflammatory properties and highlights C-IA's potential as a health-beneficial compound for future research.

Release of multifunctional peptides from kiwicha (Amaranthus caudatus) protein under in vitro gastrointestinal digestion

BACKGROUND

The multifactorial origin of many chronic diseases provides a new framework for the development of multifunctional foods. In this study, the effect of in vitro simulated gastrointestinal digestion of kiwicha (Amaranthus caudatus) proteins on the release of multifunctional peptides was evaluated.

RESULTS

Gastric digest showed higher angiotensin I converting enzyme (ACE) inhibitory activity while 60 min gastroduodenal digest showed the highest antioxidant, dipeptidyl peptidase IV (DPP-IV), α-amylase and Caco-2 cell viability inhibitory activities. Peptides >5 kDa were more effective in inhibiting colon cancer cell viability, whereas peptides <5 kDa were mainly responsible for the antioxidant, ACE, DPP-IV and α-amylase inhibitory activities. Thirteen peptides from amaranth sequenced proteins were identified. Structure-activity relationship analysis of the identified sequences pointed to three amaranth fragments, namely FLISCLL, SVFDEELS and DFIILE, as potential peptides able to concurrently exert antioxidant capacity and ability to inhibit both ACE and α-amylase.

CONCLUSIONS

Five of thirteen peptides identified in kiwicha protein digests show high potential to exert multifunctional properties. Thus kiwicha proteins might start to gain importance as ingredients for functional foods for the prevention and/or management of chronic diseases related to oxidative stress, hypertension and/or diabetes. © 2018 Society of Chemical Industry.

Palyno-morphological investigations of halophytic taxa of Amaranthaceae through SEM from Salt range of Northern Punjab, Pakistan

The pollen morphology of 11 salt tolerant plant species of family Amaranthaceae from the salt range of Northern Punjab, Pakistan has been studied. The palyno-morphological characters were examined using light and scanning electron microscope. The examined all salt tolerant species have a slight difference in size but have similarity in shape, pore ornamentation, and polarity. The observed morphological characters of pollen grains were pollen symmetry, size, shape, pore ornamentation, pore size, number of pores, exine thickness, polar and equatorial diameter and, P/E ratio. Apolar type of pollens has been observed in all species. Shape of pollens was spheroidal. Exine sculpturing of pollen grains was scabrate (six spp), microechinate (four spp), and microechinate-scabrate (one spp). Different pori numbers were observed in different species. The pantoporate aperturate and sunken pore ornamentation have been reported in all species. A pollen taxonomic key was developed using examined morphological characters for the accurate identification of halophytic taxa. The high fertility and low sterility of pollens confirmed that the selected halophytes are well-established in the salt region. The findings highlight the taxonomic significance of pollen morphology in correct identification and differentiation of salt tolerant plant species.

Morpho-palynological assessment of medicinal flora of district Lahore, Pakistan based on LM and SEM

This study was carried out to identify 20 high valued medicinal plants of District Lahore, Punjab, Pakistan with the help of the palynological studies. The distinguishing characteristics for selected species were found by systematized methods using light microscopy and Scanning Electron Microscopy. In this study, important pollen qualitative and quantitative features of these medicinal species such as polar and equatorial outline and their diameter, P/E ratio, presence or absence of pore, sculpturing of pollen, exine thickness, intine thickness, intercellular distance of exine and intine, presence or absence of spines, length of spines, width of spines, presence or absence of colpi and length of colpi, were compared. Remarkable variations in these pollen characters have been observed. Pollen grains were usually circular-semicircular (Calendula officinalis), spheroidal (Convolvulus arvensis), bilobed and trilobed (Convolvulus arvensis), spiny, (Abutilon indicum), oblate (Terminalia chebula) and elongated (Euphorbia pilulifera). In polar view Conyza bonariensis exhibited the highest pollen size [195.9 (211.6-180.2) μm]. While in equatorial view Calendula officinalis and Euphorbia pilulifera had lowest value [22.5 (20-25) μm] whereas Carissa carandas [165 (140-179) μm] appeared to be the largest. Parthenium hysterophorus showed the highest P/E ratio, that is, 1.28. Colpi were reported in only 7 species. Most of the plants showed 100% fertility but Terminalia chebula showed the least value 35%. In the present, project the diversity in pollen morphology present pollen as a valuable taxonomic tool. It is also concluded that pollen features are helpful at the specific level as well as generic level and can provide us fruitful taxonomic solutions. RESEARCH HIGHLIGHTS: Palynological flora of the medicinal plant species of district Lahore, Pakistan is investigated first time on the basis of LM and SEM and the flora is found very significant for taxonomic investigations.

From zero to hero: the past, present and future of grain amaranth breeding

Grain amaranth is an underutilized crop with high nutritional quality from the Americas. Emerging genomic and biotechnological tools are becoming available that allow the integration of novel breeding techniques for rapid improvement of amaranth and other underutilized crops. Out of thousands of edible plants, only three cereals-maize, wheat and rice-are the major food sources for a majority of people worldwide. While these crops provide high amounts of calories, they are low in protein and other essential nutrients. The dependence on only few crops, with often narrow genetic basis, leads to a high vulnerability of modern cropping systems to the predicted climate change and accompanying weather extremes. Broadening our food sources through the integration of so-called orphan crops can help to mitigate the effects of environmental change and improve qualitative food security. Thousands of traditional crops are known, but have received little attention in the last century and breeding efforts were limited. Amaranth is such an underutilized pseudocereal that is of particular interest because of its balanced amino acid and micronutrient profiles. Additionally, the C₄ photosynthetic pathway and ability to withstand environmental stress make the crop a suitable choice for future agricultural systems. Despite the potential of amaranth, efforts of genetic improvement lag considerably behind those of major crops. The progress in novel breeding methods and molecular techniques developed in model plants and major crops allow a rapid improvement of underutilized crops. Here, we review the history of amaranth and recent advances in genomic tools and give a concrete perspective how novel breeding techniques can be implemented into breeding programs. Our perspectives are transferable to many underutilized crops. The implementation of these could improve the nutritional quality and climate resilience of future cropping systems.

Betalains in Some Species of the Amaranthaceae Family: A Review

Natural pigments are largely distributed in the plant kingdom. They belong to diverse groups, with distinct biochemical pathways. Betalains with colours that range from yellow to red-violet can de divided into two main subgroups: betaxanthins and betacyanins. These types of pigments are confined into 13 families of the order Caryophyllales and in some genera of higher fungi (Amanita muscaria, Hygrocybe and Hygrophorus). The Amaranthaceae family includes diverse genera in which betalains are present: Alternanthera, Amaranthus, Beta, Chenopodium, Celosia and Gomphrena. The biosynthesis of betalains and their general biological properties were reviwed in the present work. In addition, the types of betalains present in some species of the aforementioned genera, their stability and production, as well as biological attributes, were reviewed.

Mineral composition of amaranth (Amaranthus L.) seeds of vegetable and grain usage by ARHIVBSP selection

The questions of the practical usage of the analytical scanning electron microscope JSM 600 LA by JEOL company (Japan) with EDS system - microanalysis for the studying of the ash elemental composition of seeds 9 breeds (Vegetable and Grain application) 4 species genus Amaranthus L. - A. hypochondriacus, A. cruentus, A. hybridus, A. caudatus, A. tricolor. Plant seeds by Federal center of vegetable production selection were envisaged. We studied the concentration of 14 basic elements (in weight %) contained in the mineral part of amaranth seeds. In the amaranth seeds of vegetable forms the accumulation order of the elements is the following: Ca >K >P >Mg >Si >Se >Fe >Mo ≈ S ≈ Cl ≈ Zn >Na >Al. In the seeds of the grain forms the order is different: К >P >Ca >Si >Se >Mg >Fe >Na >Mo >Cl ≈ S ≈ Mn ≈ Zn ≈ Al. The amaranth seeds of the grain forms are rich in macro - and microelements. P, K, Cl and S in the seeds of the grain forms are accumulated on 50, 37, 15 and 5% more and Si, Fe and Al in 2.6 and 1.8 times more than in the vegetable forms seeds. The breeds with the high concentration of the elements are recommended for using in the selection process. The elevated level of the essential macro- and microelements such as Ca, K, P, Mg, Mo, S and Cl stipulates the perspective of the functional products creation on the base of the studied amaranth seeds for the enrichment of the food stuffs.

Application of Chloroplast Phylogenomics to Resolve Species Relationships Within the Plant Genus Amaranthus

Amaranthus species are an emerging and promising nutritious traditional vegetable food source. Morphological plasticity and poorly resolved dendrograms have led to the need for well resolved species phylogenies. We hypothesized that whole chloroplast phylogenomics would result in more reliable differentiation between closely related amaranth species. The aims of the study were therefore: to construct a fully assembled, annotated chloroplast genome sequence of Amaranthus tricolor; to characterize Amaranthus accessions phylogenetically by comparing barcoding genes (matK, rbcL, ITS) with whole chloroplast sequencing; and to use whole chloroplast phylogenomics to resolve deeper phylogenetic relationships. We generated a complete A. tricolor chloroplast sequence of 150,027 bp. The three barcoding genes revealed poor inter- and intra-species resolution with low bootstrap support. Whole chloroplast phylogenomics of 59 Amaranthus accessions increased the number of parsimoniously informative sites from 92 to 481 compared to the barcoding genes, allowing improved separation of amaranth species. Our results support previous findings that two geographically independent domestication events of Amaranthus hybridus likely gave rise to several species within the Hybridus complex, namely Amaranthus dubius, Amaranthus quitensis, Amaranthus caudatus, Amaranthus cruentus and Amaranthus hypochondriacus. Poor resolution of species within the Hybridus complex supports the recent and ongoing domestication within the complex, and highlights the limitation of chloroplast data for resolving recent evolution. The weedy Amaranthus retroflexus and Amaranthus powellii was found to share a common ancestor with the Hybridus complex. Leafy amaranth, Amaranthus tricolor, Amaranthus blitum, Amaranthus viridis and Amaranthus graecizans formed a stable sister lineage to the aforementioned species across the phylogenetic trees. This study demonstrates the power of next-generation sequencing data and reference-based assemblies to resolve phylogenies, and also facilitated the identification of unknown Amaranthus accessions from a local genebank. The informative phylogeny of the Amaranthus genus will aid in selecting accessions for breeding advanced genotypes to satisfy global food demand.

Consumption of Amaranth Induces the Accumulation of the Antioxidant Protein Paraoxonase/Arylesterase 1 and Modulates Dipeptidyl Peptidase IV Activity in Plasma of Streptozotocin-Induced Hyperglycemic Rats

BACKGROUND/AIM

Amaranth is a source of several bioactive compounds, among which peptides with inhibitory activity upon dipeptidyl peptidase IV (DPP-IV) have been reported. However, there is no information about the action of amaranth DPP-IV-inhibitory peptides using in vivo models. The aim of this work was to evaluate the effect of amaranth consumption on plasma and kidney DPP-IV activity as well the changes in plasma proteome profile of streptozotocin (STZ)-induced hyperglycemic rats.

METHODS

Rats were fed for 12 weeks with a diet containing 20% popped amaranth grain. Kidneys and blood samples were collected for lipid profile, DPP-IV activity and expression, and proteomic analysis.

RESULTS

Total cholesterol and DPP-IV activity in plasma was increased in hyperglycemic rats, but this effect was reverted by amaranth consumption. Triacylglycerols were increased in the hyperglycemic group fed amaranth, and the highest levels of high-density lipoproteins were also observed in this group. These data correlated with the accumulation of apolipoprotein A-II in plasma. Accumulation of the antioxidant protein paraoxonase/arylesterase 1 in STZ-induced hyperglycemic rats was observed when amaranth was supplied in the diet.

CONCLUSION

This study provides new insights into the molecular mechanisms by which amaranth exerts its beneficial health action in a hyperglycemic state.

Emerging opportunities in exploring the nutritional/functional value of amaranth

Amaranthusspp. is a highly nutritive pseudocereal, rich in macronutrients and micronutrients, including vitamins and minerals.

Diversity in Grain Amaranths and Relatives Distinguished by Genotyping by Sequencing (GBS)

The genotyping by sequencing (GBS) method has become a molecular marker technology of choice for many crop plants because of its simultaneous discovery and evaluation of a large number of single nucleotide polymorphisms (SNPs) and utility for germplasm characterization. Genome representation and complexity reduction are the basis for GBS fingerprinting and can vary by species based on genome size and other sequence characteristics. Grain amaranths are a set of three species that were domesticated in the New World to be high protein, pseudo-cereal grain crops. The goal of this research was to employ the GBS technique for diversity evaluation in grain amaranth accessions and close relatives from six Amaranthus species and determine genetic differences and similarities between groupings. A total of 10,668 SNPs were discovered in 94 amaranth accessions with ApeKI complexity reduction and 10X genome coverage Illumina sequencing. The majority of the SNPs were species specific with 4,568 and 3,082 for the two grain amaranths originating in Central America Amaranthus cruentus and A. hypochondriacus and 3,284 found amongst both A. caudatus, originally domesticated in South America, and its close relative, A. quitensis. The distance matrix based on shared alleles provided information on the close relationships of the two cultivated Central American species with each other and of the wild and cultivated South American species with each other, as distinguished from the outgroup with two wild species, A. powellii and A. retroflexus. The GBS data also distinguished admixture between each pair of species and the geographical origins and seed colors of the accessions. The SNPs we discovered here can be used for marker development for future amaranth study.

In Vitro Modulation of Renin-Angiotensin System Enzymes by Amaranth (Amaranthus hypochondriacus) Protein-Derived Peptides: Alternative Mechanisms Different from ACE Inhibition

Among the factors affecting the development of cardiovascular diseases, hypertension is one of the most important. Research done on amaranth proteins has demonstrated their hypotensive capacity in vivo and in vitro; nevertheless, the mechanism underlying this effect remains unclear. The aim of this study was to analyze in vitro the inhibition of peptides derived from an amaranth hydrolysate (AHH) on other RAS enzymes other than ACE. The chymase and renin activities were studied. AHH was not able to inhibit chymase activity, although a dose-response effect was found on renin activity (IC₅₀ 0.6 mg/mL). To provide an approach to the renin inhibition mechanism, we analyzed AHH renin inhibition kinetics and performed a structural characterization of the peptides involved in the effect in terms of molecular size and hydrophobicity. Results suggest that amaranth peptides exhibit renin competitive inhibition behavior. Renin inhibition potency was directly related to peptide hydrophobicity. RP-HPLC separation of AHH and subsequent analysis of the peptide sequences showed 6 peptides belonging to 11S globulin (that can be grouped into 3 families) that would be responsible for renin inhibition. These results demonstrate that Amaranthus hypochondriacus seeds are an adequate source of peptides with renin inhibitory properties that could be used in functional food formulations.

Indigenous leafy vegetables of Eastern Africa - A source of extraordinary secondary plant metabolites

Indigenous African leafy vegetables vary enormously in their secondary plant metabolites whereat genus and the species have a great impact. In African nightshade (Solanum scabrum), spiderplant (Cleome gynandra), amaranth (Amaranthus cruentus), cowpea (Vigna unguiculata), Ethiopian kale (Brassica carinata) and common kale (Brassica oleracea) the specific secondary metabolite profile was elucidated and gained detailed data about carotenoids, chlorophylls, glucosinolates and phenolic compounds all having an appropriate contribution to health beneficial properties of indigenous African leafy vegetables. Exemplarily, various quercetin glycosides such as quercetin-3-rutinoside occur in high concentrations in African nightshade, spiderplant, and amaranth between ~1400-3300μg/g DW. Additionally the extraordinary hydroxycinnamic acid derivatives such as glucaric isomers and isocitric acid isomers are found especially in amaranth (up to ~1250μg/g DW) and spiderplant (up to 120μg/g DW). Carotenoids concentrations are high in amaranth (up to101.7μg/g DW) and spiderplants (up to 64.7μg/g DW) showing high concentrations of β-carotene, the pro-vitamin A. In contrast to the ubiquitous occurring phenolics and carotenoids, glucosinolates are only present in the Brassicales species Ethiopian kale, common kale and spiderplant characterized by diverse glucosinolate profiles. Generally, the consumption of a variety of these indigenous African leafy vegetables can be recommended to contribute to different benefits such as antioxidant activity, increase pro-vitamin A and anticancerogenic compounds in a healthy diet.

Analysis of phylogenetic relationships and genome size evolution of the Amaranthus genus using GBS indicates the ancestors of an ancient crop

The genus Amaranthus consists of 50-70 species and harbors several cultivated and weedy species of great economic importance. A small number of suitable traits, phenotypic plasticity, gene flow and hybridization made it difficult to establish the taxonomy and phylogeny of the whole genus despite various studies using molecular markers. We inferred the phylogeny of the Amaranthus genus using genotyping by sequencing (GBS) of 94 genebank accessions representing 35 Amaranthus species and measured their genome sizes. SNPs were called by de novo and reference-based methods, for which we used the distant sugarbeet Beta vulgaris and the closely related Amaranthus hypochondriacus as references. SNP counts and proportions of missing data differed between methods, but the resulting phylogenetic trees were highly similar. A distance-based neighbor joining tree of individual accessions and a species tree calculated with the multispecies coalescent supported a previous taxonomic classification into three subgenera although the subgenus A. Acnida consists of two highly differentiated clades. The analysis of the Hybridus complex within the A. Amaranthus subgenus revealed insights on the history of cultivated grain amaranths. The complex includes the three cultivated grain amaranths and their wild relatives and was well separated from other species in the subgenus. Wild and cultivated amaranth accessions did not differentiate according to the species assignment but clustered by their geographic origin from South and Central America. Different geographically separated populations of Amaranthus hybridus appear to be the common ancestors of the three cultivated grain species and A. quitensis might be additionally be involved in the evolution of South American grain amaranth (A. caudatus). We also measured genome sizes of the species and observed little variation with the exception of two lineages that showed evidence for a recent polyploidization. With the exception of two lineages, genome sizes are quite similar and indicate that polyploidization did not play a major role in the history of the genus.

Insights on Structure and Function of a Late Embryogenesis Abundant Protein from Amaranthus cruentus: An Intrinsically Disordered Protein Involved in Protection against Desiccation, Oxidant Conditions, and Osmotic Stress

Late embryogenesis abundant (LEA) proteins are part of a large protein family that protect other proteins from aggregation due to desiccation or osmotic stresses. Recently, the Amaranthus cruentus seed proteome was characterized by 2D-PAGE and one highly accumulated protein spot was identified as a LEA protein and was named AcLEA. In this work, AcLEA cDNA was cloned into an expression vector and the recombinant protein was purified and characterized. AcLEA encodes a 172 amino acid polypeptide with a predicted molecular mass of 18.34 kDa and estimated pI of 8.58. Phylogenetic analysis revealed that AcLEA is evolutionarily close to the LEA3 group. Structural characteristics were revealed by nuclear magnetic resonance and circular dichroism methods. We have shown that recombinant AcLEA is an intrinsically disordered protein in solution even at high salinity and osmotic pressures, but it has a strong tendency to take a secondary structure, mainly folded as α-helix, when an inductive additive is present. Recombinant AcLEA function was evaluated using Escherichia coli as in vivo model showing the important protection role against desiccation, oxidant conditions, and osmotic stress. AcLEA recombinant protein was localized in cytoplasm of Nicotiana benthamiana protoplasts and orthologs were detected in seeds of wild and domesticated amaranth species. Interestingly AcLEA was detected in leaves, stems, and roots but only in plants subjected to salt stress. This fact could indicate the important role of AcLEA protection during plant stress in all amaranth species studied.

Optimization of the malting process for nutritional improvement of finger millet and amaranth flours in the infant weaning food industry

Malting is a beneficial approach to improve the nutritional value of cereals used in infant preparations. Malted finger millet and amaranth might be considered as potentially appropriate gluten-free alternatives for common wheat-based weaning products, especially in case of those suffering from celiac disease. In this study, the effects of germination temperature and duration on the main nutrients of malted finger millet and amaranth, are evaluated and optimized. Grains were germinated for 24, 36 and 48 h at 22, 26 and 30 °C. In the case of finger millet, germinating for 48 h at 30 °C resulted into 17% increase in protein availability, 10% increase in total energy and 60% reduction in resistant starch (RS). For amaranth, germinating for 48 h at 26 °C was preferable, resulting in 8% increase in protein availability, 11% increase in total energy, 70% reduction in RS and a 10% increase in the linoleic acid.

Physiological and biochemical characterization of two Amaranthus species under Cr(VI) stress differing in Cr(VI) tolerance

The present study was undertaken to evaluate Cr(VI) toxicity tolerance in two Amaranthus species viz. Amaranthus viridis and Amaranthus cruentus exposed to hexavalent chromium [Cr(VI)] stress. To ascertain this, both Amaranthus species were grown under various concentrations (0, 10 and 50 μM) of Cr(VI) in the hydroponic system. After 7 days of Cr(VI) treatment, various traits such as growth, Cr accumulation, photochemistry of photosystem II (PS II) (JIP-test), oxidative stress and antioxidant defense system were analyzed. Cr(VI) treatments caused inhibition in growth and PS II photochemistry, which was accompanied with increased accumulation of Cr that results into enhanced generation of reactive oxygen species (ROS): O₂^- and H₂O₂, which subsequently induced the peroxidation of lipids and leakage of electrolyte in both the Amaranthus species. Cr(VI) accumulation, lipid peroxidation and electrolyte leakage were more pronounced in A. viridis than in A. cruentus. On the other hand, A. cruentus seedlings showed higher activities of enzymatic antioxidants: SOD, POD, CAT and GST, and non-enzymatic antioxidants: cysteine and non-protein thiols (NP-SH) levels than A. viridis. The overall results suggest that A. cruentus is more tolerant than A. viridis due to its higher antioxidant defense system that protected seedlings under Cr(VI) stress.

Overexpression of Grain Amaranth (Amaranthus hypochondriacus) AhERF or AhDOF Transcription Factors in Arabidopsis thaliana Increases Water Deficit- and Salt-Stress Tolerance, Respectively, via Contrasting Stress-Amelioration Mechanisms

Two grain amaranth transcription factor (TF) genes were overexpressed in Arabidopsis plants. The first, coding for a group VII ethylene response factor TF (i.e., AhERF-VII) conferred tolerance to water-deficit stress (WS) in transgenic Arabidopsis without affecting vegetative or reproductive growth. A significantly lower water-loss rate in detached leaves coupled to a reduced stomatal opening in leaves of plants subjected to WS was associated with this trait. WS tolerance was also associated with an increased antioxidant enzyme activity and the accumulation of putative stress-related secondary metabolites. However, microarray and GO data did not indicate an obvious correlation between WS tolerance, stomatal closure, and abscisic acid (ABA)-related signaling. This scenario suggested that stomatal closure during WS in these plants involved ABA-independent mechanisms, possibly involving reactive oxygen species (ROS). WS tolerance may have also involved other protective processes, such as those employed for methyl glyoxal detoxification. The second, coding for a class A and cluster I DNA binding with one finger TF (i.e., AhDof-AI) provided salt-stress (SS) tolerance with no evident fitness penalties. The lack of an obvious development-related phenotype contrasted with microarray and GO data showing an enrichment of categories and genes related to developmental processes, particularly flowering. SS tolerance also correlated with increased superoxide dismutase activity but not with augmented stomatal closure. Additionally, microarray and GO data indicated that, contrary to AhERF-VII, SS tolerance conferred by AhDof-AI in Arabidopsis involved ABA-dependent and ABA-independent stress amelioration mechanisms.

Combination of transglutaminase and sourdough on gluten-free flours to improve dough structure

The aim of this work was to evaluate the effects of microbial transglutaminase (mTG) and sourdough on gluten-free (GF) flours. Besides deamidation and incorporation of amines, mTG catalyses protein cross-links, modifying dough structure. Sourdough from lactic acid bacteria (LAB) and yeast modifies dough protein composition, determining proteolysis, which induce the formation of aroma precursor metabolites. The chemical-physical interactions of volatile molecules with various constituents of the matrix affect the retention of aroma compounds. Here, the effect on volatile molecule profiles and on protein networks formation after mTG treatment in sourdoughs obtained with four GF flours belonging to cereals, pseudo-cereals and legumes (rice, corn, amaranth and lentil) was investigated. Sourdough was prepared with a two-step fermentation using Lactobacillus sanfrancisciensis (LSCE1) and Candida milleri (PFL44), then mTG was added after 21 h of fermentation at increasing levels. The results showed that mTG had the capacity to modify GF flour proteins and improve protein networks formation, involving mainly the prolamin protein fraction. This is particularly relevant for the production of GF backed goods generally lacking of technological, structural and sensorial features compared with products obtained with wheat flour sourdough fermentation. Interestingly, mTG treatment of sourdough affected also the volatile composition and indeed possibly the final organoleptic properties of the products.