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Quinoa ( Chenopodium quinoa Willd), an ancient Andean seed crop, exhibits exceptional nutritional properties and resistance to abiotic stress. The species' tolerance to heavy metals has, however, not yet been investigated nor its ability to take up and translocate chromium (Cr). This study aimed to investigate the metabolic adjustments occurring upon exposure of quinoa to several concentrations (0.01–5 mM) of CrCl 3 . Young hydroponically grown plants were used to evaluate Cr uptake, growth, oxidative stress, and other biochemical parameters three and/or seven days after treatment. Leaves accumulated the lowest amounts of Cr, while roots and stems accumulated the most at low and at high metal concentrations, respectively. Fresh weight and photosynthetic pigments were reduced only by the higher Cr(III) doses. Substantially increased lipid peroxidation, hydrogen peroxide, and proline levels were observed only with 5 mM Cr(III). Except for a significant decrease at day 7 with 5 mM Cr(III), total polyphenols and flavonoids maintained control levels in Cr(III)-treated plants, whereas antioxidant activity increased in a dose-dependent manner. Maximum polyamine accumulation was observed in 1 mM CrCl 3 -treated plants. Even though α- and γ-tocopherols also showed enhanced levels only with the 1 mM concentration, tyrosine aminotransferase (TAT, EC 2.6.1.5) activity increased under Cr(III) treatment in a dose- and time-dependent manner. Taken together, results suggest that polyamines, tocopherols, and TAT activity could contribute to tolerance to 1 mM Cr(III), but not to the highest concentration that, instead, generated oxidative stress. [ABSTRACT FROM AUTHOR]

Quinoa (Chenopodium quinoa Willd) is an ancient Andean seed-producing crop well known for its exceptional nutritional properties and resistance to adverse environmental conditions, such as salinity and drought. Seed storage proteins, amino acid composition, and bioactive compounds play a crucial role in determining the nutritional value of quinoa. Seeds harvested from three Chilean landraces of quinoa, one belonging to the salares ecotype (R49) and two to the coastal-lowlands ecotype, VI-1 and Villarrica (VR), exposed to two levels of salinity (100 and 300 mM NaCl) were used to conduct a sequential extraction of storage proteins in order to obtain fractions enriched in albumins/globulins, 11S globulin and in prolamin-like proteins. The composition of the resulting protein fractions was analyzed by one- and two-dimensional polyacrylamide gel electrophoresis. Results confirmed a high polymorphism in seed storage proteins; the two most representative genotype-specific bands of the albumin/globulin fraction were the 30- and 32-kDa bands, while the 11S globulin showed genotype-specific polymorphism for the 40- and 42-kDa bands. Spot analysis by mass spectrometry followed by in silico analyses were conducted to identify the proteins whose expression changed most significantly in response to salinity in VR. Proteins belonging to several functional categories (i.e., stress protein, metabolism, and storage) were affected by salinity. Other nutritional and functional properties, namely amino acid profiles, total polyphenol (TPC) and flavonoid (TFC) contents, and antioxidant activity (AA) of protein extracts were also analyzed. With the exception of Ala and Met in R49, all amino acids derived from protein hydrolysis were diminished in seeds from salt-treated plants, especially in landrace VI-1. By contrast, several free amino acids were unchanged or increased by salinity in R49 as compared with VR and VI-1, suggesting a greater tolerance in the salares landrace. VR had the highest TPC and AA under non-saline conditions. Salinity increased TPC in all three landraces, with the strongest increase occurring in R49, and enhanced radical scavenging capacity in R49 and VR. Overall, results show that salinity deeply altered the seed proteome and amino acid profiles and, in general, increased the concentration of bioactive molecules and AA of protein extracts in a genotype-dependent manner. [ABSTRACT FROM AUTHOR]

• Polyamines are plant growth regulators also involved in stress responses. • They interact with other PGRs and NO and their catabolism produces H 2 O 2. • Their exogenous application to crops improves several functional processes. • Seed priming is a method to enhance seedling establishment and stress tolerance. • Priming quinoa seeds with PAs improved germination and modulated gene expression. The importance of polyamines (PAs) in plant growth and development was recognised several decades ago and, since then, their role in cell proliferation, embryogenesis, organogenesis, flowering, fruit development and ripening, etc. has been investigated to a great extent. In more recent years, most of the attention on PAs has been focussed on their functions in biotic and, especially, abiotic stress responses. Exogenous application, transgenic plants over- or under-expressing PA biosynthetic genes, and mutants have been used to unveil their essential contribution to plant tolerance to salinity, drought, chilling, and heavy metal stresses, among others. In parallel, knowledge on their mechanisms of action has increased greatly and it is today evident that PA functions depend upon their ability to (a) bind electrostatically or covalently to numerous compounds thereby modulating membrane, cell wall, nucleic acid, and protein structure and functions, (b) produce hydrogen peroxide via their catabolic pathways, (c) interact with the biosynthetic and signaling pathways of practically all known phytohormones, and (d) interact with nitric oxide. In this review, a state-of-the-art overview of PA functions in plants and their possible applications in mitigating stress in crop plants is provided. The potential of seed priming with PAs as an economically and environmentally valid approach for enhancing plant tolerance to adverse environmental conditions is discussed and some results from our study on quinoa and salt stress are presented. [ABSTRACT FROM AUTHOR]

The nutraceutical interest in quinoa (Chenopodium quinoa Willd.) seeds is associated with the presence of macronutrients, micronutrients, minerals, vitamins, and polyphenols. In particular, polyphenols contribute to the health-promoting effects of this food crop, and their levels are influenced by environmental conditions. Production of quinoa is recently being explored in temperate climate areas, including Italy. The aim of this research was to assess the profile of bioactive compounds in seeds of two quinoa varieties, Regalona-Baer and Titicaca, grown in northern Italy, compared to that of seeds of those varieties grown in Chile and Denmark, respectively. High-performance liquid chromatography-diode array detector (HPLC-DAD) analysis of phenolic acid and flavonoid profiles, both in their free and soluble conjugated forms, showed that the main differences between Regalona grown in Chile and Italy were for the free vanillic acid and daidzein contents, while the two Titicaca samples mainly differed in quercetin derivative levels. The total phenolic index was comparable in Titicaca and Regalona, and only a slight decrease in this parameter was found in seeds of the two varieties grown in Italy. The in vitro antioxidant activity of seed extracts, evaluated by means of three different assays, indicated that it correlated with flavonol (quercetin derivative) levels. In conclusion, the results indicate that, although environmental conditions alter the polyphenolic profile and biological activities, it is possible to grow good-quality quinoa in northern Italy. [ABSTRACT FROM AUTHOR]

Many areas of the world are affected simultaneously by salinity and heavy metal pollution. Halophytes are considered as useful candidates in remediation of such soils due to their ability to withstand both osmotic stress and ion toxicity deriving from high salt concentrations. Quinoa (Chenopodium quinoa Willd) is a halophyte with a high resistance to abiotic stresses (drought, salinity, frost), but its capacity to cope with heavy metals has not yet been fully investigated. In this pot experiment, we investigated phytoextraction capacity, effects on nutrient levels (P and Fe), and changes in gene expression in response to application of Cr(III) in quinoa plants grown on saline or non-saline soil. Plants were exposed for three weeks to 500 mg kg−1 soil of Cr(NO 3) 3 ·9H 2 O either in the presence or absence of 150 mM NaCl. Results show that plants were able tolerate this soil concentration of Cr(III); the metal was mainly accumulated in roots where it reached the highest concentration (ca. 2.6 mg g−1 DW) in the presence of NaCl. On saline soil, foliar Na concentration was significantly reduced by Cr(III). Phosphorus translocation to leaves was reduced in the presence of Cr(III), while Fe accumulation was enhanced by treatment with NaCl alone. A real-time RT-qPCR analysis was conducted on genes encoding for sulfate, iron, and phosphate transporters, a phytochelatin, a metallothionein, glutathione synthetase, a dehydrin, Hsp70, and enzymes responsible for the biosynthesis of proline (P5CS), glycine betaine (BADH), tocopherols (TAT), and phenolic compounds (PAL). Cr(III), and especially Cr(III)+NaCl, affected transcript levels of most of the investigated genes, indicating that tolerance to Cr is associated with changes in phosphorus and sulfur allocation, and activation of stress-protective molecules. Moderately saline conditions, in most cases, enhanced this response, suggesting that the halophytism of quinoa could contribute to prime the plants to respond to chromium stress. • Salinity and heavy metal pollution are one of the world's major environmental concerns. • Quinoa is a halophytic crop and highly tolerant to multiple stresses. • Plants did not show any toxicity symptoms in the presence of Cr with or without NaCl. • Cr and/or NaCl severely affected the uptake of nutrients. • The presence of Cr with or without NaCl modified the expression of several genes. [ABSTRACT FROM AUTHOR]

Quinoa (Chenopodium quinoa Willd.), a model halophytic crop species, was used to shed light on salt tolerance mechanisms at the transcriptomic level. An RNA-sequencing analysis of genotype R49 at an early vegetative stage was performed by Illumina paired-ends method comparing high salinity and control conditions in a time-course pot experiment. Genome-wide transcriptional salt-induced changes and expression profiling of relevant salt-responsive genes in plants treated or not with 300 mM NaCl were analyzed after 1 h and 5 days. We obtained up to 49 million pairs of short reads with an average length of 101 bp, identifying a total of 2416 differentially expressed genes (DEGs) based on the treatment and time of sampling. In salt-treated vs. control plants, the total number of up-regulated and down-regulated genes was 945 and 1471, respectively. The number of DEGs was higher at 5 days than at 1 h after salt treatment, as reflected in the number of transcription factors, which increased with time. We report a strong transcriptional reprogramming of genes involved in biological processes like oxidation-reduction, response to stress and response to abscisic acid (ABA), and cell wall organization. Transcript analyses by real-time RT- qPCR supported the RNA-seq results and shed light on the contribution of roots and shoots to the overall transcriptional response. In addition, it revealed a time-dependent response in the expression of the analyzed DEGs, including a quick (within 1 h) response for some genes, suggesting a "stress-anticipatory preparedness" in this highly salt-tolerant genotype. [ABSTRACT FROM AUTHOR]

Chenopodium quinoa Willd. (quinoa) is a halophyte for which some parameters linked to salt tolerance have been investigated separately in different genotypes and under different growth conditions. In this study, several morphological and metabolic responses were analysed in parallel after exposure to salinity. In vitro seed germination was initially delayed by a 150 mM NaCl treatment but eventually reached the same level as the control (0 mM NaCl), whereas seedling root growth was enhanced; both parameters were moderately inhibited (~35-50%) by 300 mM NaCl. In pot grown plants, plant size was reduced by increasing salinity (0-750 mM NaCl). Transpiration and stomatal conductance were decreased at the highest salinity levels tested, consistent with reduced stomatal density and size. The density of epidermal bladder cells (EBCs) on the leaf surface remained unaffected up to 600 mM NaCl. Tissue contents of Na+ and Cl- increased dramatically with salt treatment, but resulted in only a 50% increase in Na+ from 150 to 750 mM NaCl. Internal K+ was unaffected up to 450 mM NaCl but increased at the highest salinity levels tested. Excretion through sequestration into EBCs was limited (generally ≤20%) for all ions. A modest dose-dependent proline accumulation, and concomitant reduction in total polyamines and putrescine efflux occurred in NaCl-treated plants. Results confirm the importance of inorganic ions for osmotic adjustment, the plant's ability to maintain K+ levels and the involvement of putrescine efflux in maintaining ionic balance under high salinity conditions. Conversely, ion excretion and proline appear to play a minor role. Taken together these results indicate which parameters could be used for future comparison among different genotypes. [ABSTRACT FROM AUTHOR]

Saponins (SAPs) are a diverse family of plant secondary metabolites and due to their biological activities, SAPs can be utilised as biopesticides and as therapeutic compounds. Given their widespread industrial use, a search for alternative sources of SAPs is a priority. Quinoa ( Chenopodium quinoa Willd) is a valuable food source that is gaining importance worldwide for its nutritional and nutraceutical properties. SAPs from quinoa seed coats could represent a new sustainable source to obtain these compounds in high quantities due to the increasing production and worldwide expansion of the crop. This research aims to characterise saponins of seed coat waste products from six different quinoa varieties for their potential use as a saponin source. Gas chromatography (GC)- and Liquid chromatography (LC)- with mass spectrometry (MS) were applied for qualitative and relative quantitative analysis of saponins. GC–MS led to the identification of three main aglycones, oleanolic acid (Ole), hederagenin (Hed), and a phytolaccagenic acid (Phy), while LC–MS enabled characterization of 24 SAPs with varying sugar moieties. Hed was the most abundant aglycone, followed by Phy and Oledepending on the genotype. Saponin distribution and relative abundances are discussed in the light of genotype provenance and agronomic features. Improved knowledge on the phytochemicals present in quinoa varieties might help in finding valuable and sustainable uses for quinoa SAPs in agroindustry as biopesticides as well as in the production of food and pharmaceuticals. [ABSTRACT FROM AUTHOR]

To further our understanding of the mechanisms governing salt stress responses and adaptation in halophytes, we explored morphological, metabolic, and gene expression responses to high salinity in quinoa ( Chenopodium quinoa Willd). The main objective of this study was to analyze selected responsive genes in a time-course experiment to test for expression kinetics and to compare short-term salt-induced effects at the transcript level between two Chilean landraces belonging to different ecotypes. Quinoa genotypes exhibit a large variability in their responses to salinity, but it is not clear whether this is strictly related to the ecotype to which they belong. We tested this hypothesis by comparing the expression levels of genes involved in growth, ion homeostasis, abscisic acid (ABA) biosynthesis, perception, and conjugate cleavage, polyamine (PA) biosynthesis and oxidation, and proline biosynthesis as well as genes encoding ABA-dependent and −independent transcription factors. Landraces R49 ( salares ecotype) and Villarrica (VR, coastal-lowlands ecotype) were analyzed from 0.5 to 120 h after transfer to saline (300 mM NaCl) or non-saline (control) medium. All the genes, except CqSOS1 and CqNHX , were investigated here for the first time in quinoa under salt stress. Transcript levels were determined by quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) analysis. Germination, seedling growth, ABA, and PA contents were evaluated in parallel. Even though on saline medium germination was inhibited in VR but not in R49, seedling growth reduction at 120 h was not substantially different in the two landraces. The ABA biosynthetic enzyme NCED was the most strongly salt-induced gene; ABA content was similarly enhanced (shoots) or unaffected (roots) in both R49 and VR. NaCl treatment also altered transcript levels of some PA metabolic enzymes and the PA profile leading to an enhanced ratio between the higher PAs and putrescine. All other genes also exhibited similar expression profiles in response to salinity in the two landraces especially in roots, while in shoots some differences were observed. Our results provide new information indicating that crucial salt adaptation strategies at the molecular level and in terms of ABA and PA contents are shared by the coastal-lowlands and salares landraces; however, the timing of the onset of transcriptional changes (e.g., NCED , ABF3 , and RD22 ) may reflect genotype-dependent constitutive and/or inducible adaptive strategies. [ABSTRACT FROM AUTHOR]

Quinoa ( Chenopodium quinoa Willd.) is a highly salt-tolerant species subdivided into five ecotypes and exhibiting broad intra-specific differences in tolerance levels. In a greenhouse study, Chilean landraces belonging either to the salares (R49) or coastal lowlands (VI-1, Villarrica) ecotype with contrasting agro-ecological origins were investigated for their responses to high salinity. The effects of two levels of salinity, 100 (T1) and 300 (T2) mM NaCl, on plant growth and on some physiological parameters were measured. Leaf and root Na + accumulation differed among landraces. T2 reduced growth and seed yield in all landraces with maximum inhibition relative to controls in R49. Salinity negatively affected chlorophyll and total polyphenol content (TPC) in VI-1 and Villarrica but not R49. Germination on saline or control media of seeds harvested from plants treated or not with NaCl was sometimes different; the best performing landrace was R49 insofar as 45–65% of seeds germinated on 500 mM NaCl-containing medium. In all landraces, average seedling root length declined strongly with increasing NaCl concentration, but roots of R49 were significantly longer than those of VI-1 and Villarrica up to 300 mM NaCl. Salt caused increases in seed TPC relative to controls, but radical scavenging capacity was higher only in seeds from T2 plants of R49. Total SDS-extractable seed proteins were resolved into distinct bands (10–70 kDa) with some evident differences between landraces. Salt-induced changes in protein patterns were landrace-specific. The responses to salinity of the salares landrace are discussed in relation to its better adaptation to an extreme environment. [ABSTRACT FROM AUTHOR]

Abstract: Chenopodium quinoa (Willd.) is an Andean plant showing a remarkable tolerance to abiotic stresses. In Chile, quinoa populations display a high degree of genetic distancing, and variable tolerance to salinity. To investigate which tolerance mechanisms might account for these differences, four genotypes from coastal central and southern regions were compared for their growth, physiological, and molecular responses to NaCl at seedling stage. Seeds were sown on agar plates supplemented with 0, 150 or 300mM NaCl. Germination was significantly reduced by NaCl only in accession BO78. Shoot length was reduced by 150mM NaCl in three out of four genotypes, and by over 60% at 300mM (except BO78 which remained more similar to controls). Root length was hardly affected or even enhanced at 150mM in all four genotypes, but inhibited, especially in BO78, by 300mM NaCl. Thus, the root/shoot ratio was differentially affected by salt, with the highest values in PRJ, and the lowest in BO78. Biomass was also less affected in PRJ than in the other accessions, the genotype with the highest increment in proline concentration upon salt treatment. Free putrescine declined dramatically in all genotypes under 300mM NaCl; however (spermidine+spermine)/putrescine ratios were higher in PRJ than BO78. Quantitative RT-PCR analyses of two sodium transporter genes, CqSOS1 and CqNHX, revealed that their expression was differentially induced at the shoot and root level, and between genotypes, by 300mM NaCl. Expression data are discussed in relation to the degree of salt tolerance in the different accessions. [Copyright &y& Elsevier]