A comparative analysis of the nutrient and phytochemical richness among different varieties of quinoa in China.

Quinoa is a nutrient-dense pseudocereal that has garnered global attention for its potential to bolster food security and nutrition. Despite its celebrated status, the detailed nutritional profiles of various quinoa varieties remain poorly understood, which poses a significant barrier to the strategic cultivation and utilization of quinoa's genetic diversity to combat malnutrition. The impetus for this research lies in the urgent need to identify superior quinoa strains that can be tailored to meet specific nutritional requirements and adapt to diverse agro-ecological zones. Our findings reveal substantial variation in nutrient content across different quinoa varieties, highlighting the variety ZLZX-8 as a particularly nutrient-rich strain with the highest levels of protein, fat, essential fatty acids, amino acids, and key minerals such as Mg, K, and Zn. Moreover, ZLZX-8's exceptional antioxidant capacity suggests it may have additional health benefits beyond its macronutrient profile. In contrast, ZLZX-7 stands out for its dietary fiber and phenolic content, which are critical for digestive health and disease prevention, respectively. Meanwhile, ZLZX-5, with its high starch content, could be better suited for energy production in dietary applications. Notably, the study also uncovers a correlation between grain color and nutrient profile, with colored quinoa varieties exhibiting superior fiber, inositol, phenolic content, and antioxidant activity compared to their white counterparts. This work lays the groundwork for an informed selection of quinoa varieties that can enhance dietary quality, support local and global food systems, and contribute to the fight against malnutrition.

Genome-wide association study, combined with bulk segregant analysis, identify plant receptors and defense related genes as candidate genes for downy mildew resistance in quinoa.

BACKGROUND: Downy mildew is the most relevant disease of quinoa and the most widespread. Though, little is known about the genetics of resistance to this disease. The objective of this study was to identify the genomic regions controlling downy mildew resistance in quinoa and candidate genes for this trait. With this aim we carried out a GWAS analysis in a collection formed by 211 quinoa accessions from different origins. This approach was combined with inheritance studies and Bulk Segregant Analysis (BSA) in a segregating population. RESULTS: GWAS analysis identified 26 genomic regions associated with the trait. Inheritance studies in a F2 population segregating for resistance revealed the existence of a major single dominant gene controlling downy mildew complete resistance in quinoa accession PI614911. Through BSA, this gene was found to be located in chromosome 4, in a region also identified by GWAS. Furthermore, several plant receptors and resistance genes were found to be located into the genomic regions identified by GWAS and are postulated as candidate genes for resistance. CONCLUSIONS: Until now, little was known about the genetic control of downy mildew resistance in quinoa. A previous inheritance study suggested that resistance to this disease was a quantitative polygenic trait and previous GWAS analyses were unable to identify accurate markers for this disease. In our study we demonstrate the existence of, at least, one major gene conferring resistance to this disease, identify the genomic regions involved in the trait and provide plausible candidate genes involved in defense. Therefore, this study significantly increases our knowledge about the genetics of downy mildew resistance and provides relevant information for breeding for this important trait.

Optimizing Soil Health and Sorghum Productivity through Crop Rotation with Quinoa.

Crop rotation has been considered a potential solution to mitigate the negative effects of the continuous cropping of sorghum, including soil quality issues, inadequate plant development, and diminished yield and quality. A two-year field experiment was conducted to compare the effects of sorghum-sorghum continuous cropping and quinoa-sorghum rotation on soil properties and sorghum yield. The treatments were arranged in a randomized complete block design with three replicates. Sorghum seeds (Jinza 22) and quinoa seeds ('Jiaqi 1' variety) were used. Soil samples were collected before and during the experiment for the analysis of physicochemical properties. The yield traits of sorghum were measured at maturity. The results showed that soil nutrients and organic matter were higher in the top 0-20 cm soil depth compared to 20-40 cm depth, with significant differences observed between cropping systems. Sorghum-quinoa cropping increased soil total N and organic matter, particularly at the jointing and maturity stages of sorghum. However, the available phosphorus was higher under continuous cropping at all growth stages. Crop rotation significantly improved sorghum yield traits, including spike fresh weight, spike dry weight, grain weight per spike, and grain yield per hectare. A correlation analysis revealed positive relationships between soil total N, organic matter, and sorghum yield. Overall, sorghum-quinoa rotation demonstrated potential for improving soil fertility and enhancing crop productivity compared to continuous cropping, although further studies are needed to explore the long-term effects and optimize management practices.

Effect of Gibberellic Acid and Mechanical Scarification on the Germination and Seedling Stages of Chenopodium quinoa Willd. under Salt Stress.

Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte renowned for its importance in enhancing food security, and it supports forage production across diverse climatic regions. The objective of this study is to examine the impacts of multiple pre-treatment methods on C. quinoa seed (Titicaca cultivar) germination parameters, identify the optimum pre-treatment to diminish the consequence of salinity, and promote the productivity of this crop, especially in marginal environments. For this purpose, a spectrum of sodium chloride (NaCl) concentrations spanning from 0 to 500 mM and gibberellic acid (GA3) concentrations ranging from 0 to 300 ppm were tested, and mechanical scarification (MS) was carried out. The effect of a combination of these pretreatment NaCl/GA3 and NaCl/MS on the germination parameters of C. quinoa seed was also investigated. The results showed that the total germination, vigor index, and germination index decreased progressively with an increase in salinity. Hence, salinity exhibited a notable influence on most germination parameters. Moreover, seeds scarified with 500 mM of NaCl negatively affected all measured parameters. In contrast, gibberellic acid applied at 200 ppm was effective on most of the parameters measured, particularly under 100 mM of NaCl. These findings indicate that immersing seeds in gibberellic acid could mitigate the adverse impacts of salinity.

Potential structure-function relationships of pectic polysaccharides from quinoa microgreens: Impact of various esterification degrees.

Pectic polysaccharides are one of the most vital functional ingredients in quinoa microgreens, which exhibit numerous health-promoting benefits. Nevertheless, the detailed information about the structure-function relationships of pectic polysaccharides from quinoa microgreens (QMP) remains unknown, thereby largely restricting their applications as functional foods or fortified ingredients. Therefore, to unveil the possible structure-function relationships of QMP, the mild alkali de-esterification was utilized to modify QMP, and then the correlations of esterification degrees of native and modified QMPs to their biological functions were systematically investigated. The results showed that the modified QMPs with different esterification degrees were successfully prepared by the mild alkali treatment, and the primary chemical structure (e.g., compositional monosaccharides and glycosidic linkages) of the native QMP was overall stable after the de-esterified modification. Furthermore, the results revealed that the antioxidant capacity, antiglycation effect, prebiotic potential, and immunostimulatory activity of the native QMP were negatively correlated to its esterification degree. In addition, both native and modified QMPs exerted immunostimulatory effects through activating the TLR4/NF-κB signaling pathway. These results are conducive to unveiling the precise structure-function relationships of QMP, and can also promote its applications as functional foods or fortified ingredients.

A Quantitative Real-Time PCR Method to Detect the Quinoa Downy Mildew Pathogen, Peronospora variabilis.

Quinoa downy mildew, caused by Peronospora variabilis, is the most devastating disease of quinoa globally. Rapid, sensitive diagnostic methods are needed to detect and quantify this pathogen in seeds and plant tissue. A hydrolysis probe-based quantitative real-time PCR (qPCR) assay including a competitive internal control was developed for P. variabilis detection. This assay could detect as low as 20 ag of DNA or approximately 25 internal transcribed spacer (ITS) copies per reaction with efficiencies ranging from 93.9 to 98.2%. No non-target amplification was observed when tested against DNA from other downy mildew pathogens and related oomycetes. Peronospora variabilis strains from multiple countries were detected using this assay. The assay was successfully applied to quantify the pathogen in quinoa seeds from a field trial conducted in Washington State. Downy mildew disease was recorded on all 14 genotypes with the genotypes 104.88 and 106.49 recording the highest area under the disease progress values (3,236 ± 303 SE and 2,851 ± 198, respectively) while J6 and Dutchess recorded the lowest (441 ± 107 and 409 ± 129, respectively). Seed washes obtained from field samples were subjected to the qPCR assay, and the pathogen was detected in all samples. The highest pathogen ITS copy number recorded with 106.49 (194,934 ± 38,171 SE), while the lowest was observed in Pasto (5,971 ± 1,435) and Riobamba (9,954 ± 4,243). This qPCR assay could lead to improved detection and quantification of P. variabilis as well as increased understanding of quinoa-P. variabilis interactions and epidemiology.

Ecdysterone and Turkesterone-Compounds with Prominent Potential in Sport and Healthy Nutrition.

The naturally occurring compounds ecdysterone and turkesterone, which are present in plants, including Rhaponticum carthamoides Willd. (Iljin), Spinacia oleracea L., Chenopodium quinoa Willd., and Ajuga turkestanica (Regel) Briq, are widely recognized due to their possible advantages for both general health and athletic performance. The current review investigates the beneficial biological effects of ecdysterone and turkesterone in nutrition, highlighting their roles not only in enhancing athletic performance but also in the management of various health problems. Plant-based diets, associated with various health benefits and environmental sustainability, often include sources rich in phytoecdysteroids. However, the therapeutic potential of phytoecdysteroid-rich extracts extends beyond sports nutrition, with promising applications in treating chronic fatigue, cardiovascular diseases, and neurodegenerative disorders.

Site-directed genotype screening for elimination of antinutritional saponins in quinoa seeds identifies TSARL1 as a master controller of saponin biosynthesis selectively in seeds.

Climate change may result in a drier climate and increased salinization, threatening agricultural productivity worldwide. Quinoa (Chenopodium quinoa) produces highly nutritious seeds and tolerates abiotic stresses such as drought and high salinity, making it a promising future food source. However, the presence of antinutritional saponins in their seeds is an undesirable trait. We mapped genes controlling seed saponin content to a genomic region that includes TSARL1. We isolated desired genetic variation in this gene by producing a large mutant library of a commercial quinoa cultivar and screening the library for specific nucleotide substitutions using droplet digital PCR. We were able to rapidly isolate two independent tsarl1 mutants, which retained saponins in the leaves and roots for defence, but saponins were undetectable in the seed coat. We further could show that TSARL1 specifically controls seed saponin biosynthesis in the committed step after 2,3-oxidosqualene. Our work provides new important knowledge on the function of TSARL1 and represents a breakthrough for quinoa breeding.

Metabolomics Characterization of Phenolic Compounds in Colored Quinoa and Their Relationship with In Vitro Antioxidant and Hypoglycemic Activities.

Chenopodium quinoa Willd. is rich in phenolic compounds and exhibits diverse biological activities. Few studies have focused on the effect of colored quinoa's phenolic profile on potential biological activity. This study used a UPLC-MS/MS-based metabolomic approach to examine the quinoa phenolics and their association with in vitro antioxidant and hypoglycemic properties. In total, 430 polyphenols, mainly phenolic acids, flavonoids, and flavonols, were identified. Additionally, 121, 116, and 148 differential polyphenols were found between the white and black, white and red, and black and red comparison groups, respectively; 67 polyphenols were screened as shared key differential metabolites. Phenylalanine, tyrosine, and the biosynthesis of plant secondary metabolites were the main differently regulated pathways. Black quinoa had better total phenolic contents (643.68 mg/100 g DW) and antioxidant capacity, while white quinoa had better total flavonoid contents (90.95 mg/100 g DW) and in vitro α-amylase (IC50 value of 3.97 mg/mL) and α-glucosidase (IC50 value of 1.08 mg/mL) inhibition activities. Thirty-six polyphenols, including epicatechin and linarin, etc., were highly correlated with in vitro antioxidant activity, while six polyphenols, including tiliroside and chrysoeriol, etc., were highly correlated with in vitro hypoglycemic activity. This study may provide important information for colored quinoa resources to develop their healthy food applications.

Comment on the "Does saponin in quinoa really embody the source of its bitterness?"

Saponins are considered the main source of the bitter taste of quinoa, however, it has not been confirmed by Song et al. (2024). These authors suggested that saponin extracts contribute to the umami taste, however, the stronger source of the bitter taste may be the flavonoids contained in the extracts. It is an interesting finding in view of the flavonoids role in the field of food sciences. The UPLC-MS results showed that besides saponins, also polyphenols were present in the analyzed samples. However, the presented results of UPLC-MS analysis should be substantially improved, mainly with respect to the reported accurate masses and retention times, as described in details in this comment.

Genome-wide identification of polyamine metabolism and ethylene synthesis genes in Chenopodium quinoa Willd. and their responses to low-temperature stress.

BACKGROUND: Quinoa (Chenopodium quinoa Willd.) is valued for its nutritional richness. However, pre-harvest sprouting poses a significant threat to yield and grain quality. This study aims to enhance our understanding of pre-harvest sprouting mitigation strategies, specifically through delayed sowing and avoiding rainy seasons during quinoa maturation. The overarching goal is to identify cold-resistant varieties and unravel the molecular mechanisms behind the low-temperature response of quinoa. We employed bioinformatics and genomics tools for a comprehensive genome-wide analysis of polyamines (PAs) and ethylene synthesis gene families in quinoa under low-temperature stress. RESULTS: This involved the identification of 37 PA biosynthesis and 30 PA catabolism genes, alongside 227 ethylene synthesis. Structural and phylogenetic analyses showcased conserved patterns, and subcellular localization predictions indicated diverse cellular distributions. The results indicate that the PA metabolism of quinoa is closely linked to ethylene synthesis, with multiple genes showing an upregulation in response to cold stress. However, differential expression within gene families suggests a nuanced regulatory network. CONCLUSIONS: Overall, this study contributes valuable insights for the functional characterization of the PA metabolism and ethylene synthesis of quinoa, which emphasize their roles in plant low-temperature tolerance and providing a foundation for future research in this domain.

Natural compounds proposed for the management of non-alcoholic fatty liver disease.

Although non-alcoholic fatty liver disease (NAFLD) presents as an intricate condition characterized by a growing prevalence, the often-recommended lifestyle interventions mostly lack high-level evidence of efficacy and there are currently no effective drugs proposed for this indication. The present review delves into NAFLD pathology, its diverse underlying physiopathological mechanisms and the available in vitro, in vivo, and clinical evidence regarding the use of natural compounds for its management, through three pivotal targets (oxidative stress, cellular inflammation, and insulin resistance). The promising perspectives that natural compounds offer for NAFLD management underscore the need for additional clinical and lifestyle intervention trials. Encouraging further research will contribute to establishing more robust evidence and practical recommendations tailored to patients with varying NAFLD grades.

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

Folate was enriched during quinoa germination, while molecular mechanisms were not well understood. In this study, three quinoa varieties were selected for germination, and changes in substrate content and enzyme activity of the folate biosynthesis pathway were monitored. 5-Methyltetrahydrofolate (5-CH3-THF) and 5-formyltetrahydrofolate (5-CHO-THF) were significantly enriched in quinoa sprouts. Among the selected varieties, QL-2 exhibited the lowest content of the oxidation product MeFox and the highest total folate content. Based on transcriptome analysis, the p-ABA branch was found to be crucial for folate accumulation, while the pterin branch served as a key control point for the one carbon pool by folate pathway, which limited further folate biosynthesis. In the one carbon pool by folate pathway, genes CqMTHFR and CqAMT significantly contributed to the enrichment of 5-CH3-THF and 5-CHO-THF. Findings gained here would facilitate the potential application of quinoa sprouts as an alternative strategy for folate supplementation.

Genotoxicity Assessment of Quinoin, a Ribosome Inactivating Protein from Quinoa Seeds, in the Teleost Danio rerio.

BACKGROUND: Ribosome inactivating proteins (RIPs) are N-glycosylases found in various plants that are able to specifically and irreversibly inhibit protein translation, thereby leading to cell death. Their cytotoxic properties have attracted attention in the medical field in the context of developing new anticancer therapies. Quinoin is a novel toxic enzyme obtained from quinoa seeds and classified as a type 1 RIP (Chenopodium quinoa Willd.). Recently, quinoin was found to be cytotoxic to normal fibroblasts and keratinocytes in vitro, as well as to several tumor cell lines. METHODS: The aim of this study was to evaluate the in vitro and in vivo genotoxicity of quinoin in a zebrafish model. We evaluated its ability to induce DNA fragmentation, genomic instability, and reactive oxygen species (ROS) generation by means of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) reaction, randomly amplified polymorphic DNA (RAPD) Polymerase Chain Reaction (PCR) technique, and dichlorofluorescine (DCF) assay, respectively. RESULTS: Quinoin was found to cause genomic damage in zebrafish, as shown by DNA fragmentation, polymorphic variations leading to genomic instability, and oxidative stress. Interestingly, longer quinoin treatment caused less damage than shorter treatments. CONCLUSIONS: This study demonstrated ROS-mediated genotoxicity of quinoin toward the zebrafish genome. The reduced damage observed after longer quinoin treatment could indicate the activation of detoxification mechanisms, activation of repair mechanisms, or the loss of protein activity due to enzymatic digestion. In order to clarify the genotoxic actions of quinoin, further investigations of the response pathways to DNA damage are needed. Overall, the ability of quinoin to cause breaks and instability in DNA, together with its clear cytotoxicity, make it an interesting candidate for the development of new drugs for cancer treatment.

Response surface methodology based development of an optimized polyherbal formulation and evaluation of its anti-diabetic and anti-obesity potential in high-fat diet-induced obese mice.

Background and aim: The seeds of Nelumbo nucifera, Chenopodium quinoa and Salvia hispanica are known as super foods due to their various therapeutic properties. The present study aimed to develop an optimized polyherbal formulation from edible seeds aqueous extract and to evaluate its anti-diabetic and lipase inhibitory effect on diet-induced obese diabetic mice. Experimental procedure: Response surface methodology based various formulations were evaluated for their potent anti-diabetic, lipase-inhibitory and antioxidant activities. Acute toxicity of the best optimized formulation was conducted. The mice were fed a high fat diet for 10 weeks resulting in hyperglycemia and obesity. Oral tolerance tests (sucrose, starch and lipid) of the formulation were performed. The mice were supplemented with different doses (125, 250 and 500 mg/kg) of the formulation for 6 weeks. The body weight and blood glucose level were monitored on a weekly basis. Finally, histological alterations and lipid profiles were analysed. Results and conclusion: The formulation containing equal concentration (1.5 mg/ml) of each seed extract showed maximum bioactivities. The formulation was found to be safe during toxicity assay. The tolerance tests supported the anti-diabetic and anti-obesity effect. Higher dose (500 mg/kg) of the formulation significantly (p < 0.01) lowered elevated fasting blood glucose, lipid indices and ameliorated the histological alterations in liver, kidney and pancreas caused by high fat diet. We demonstrated for the first time that the developed aqueous extract optimized formulation possess anti-diabetic and anti-obesity potential and thus could be used as adjuvant therapy for holistic management of type 2 diabetes mellitus.

Structure, ultrastructure and cation accumulation in quinoa epidermal bladder cell complex under high saline stress.

Quinoa is a facultative halophyte with excellent tolerance to salinity. In this study, the epidermal bladder cell complex (EBCc) of quinoa leaves was studied to determine their cellular characteristics and involvement in salt tolerance. We used light microscopy, confocal RAMAN microscopy, confocal fluorescence microscopy, transmission electron microscopy, and environmental scanning electron microscopy complemented by energy dispersive X-ray analysis. Ionic content was quantified with flame atomic absorption spectroscopy and with flame emission photometry. Results show that: (i) the number of EBCcs remains constant but their density and area vary with leaf age; (ii) stalk cells store lipids and exhibit thick walls, bladder cells present carotenes in small vesicles, oxalate crystals in vacuoles and lignin in their walls and both stalk and bladder cells have cuticles that differ in wax and cutin content; (iii) chloroplasts containing starch can be found on both stalk and bladder cells, and the latter also presents grana; (iv) plasmodesmata are observed between the stalk cell and the bladder cell, and between the epidermal cell and the stalk cell, and ectodesmata-like structures are observed on the bladder cell. Under high salinity conditions, (v) there is a clear tendency to accumulate greater amounts of K+ with respect to Na+ in the bladder cell; (vi) stalk cells accumulate similar amounts of K+ and Na+; (vii) Na+ accumulates mainly in the medullary parenchyma of the stem. These results add knowledge about the structure, content, and role of EBCc under salt stress, and surprisingly present the parenchyma of the stem as the main area of Na+ accumulation.

Insight into neofunctionalization of 2,3-oxidosqualene cyclases in B,C-ring-opened triterpene biosynthesis in quinoa.

Bioactive triterpenes feature complex fused-ring structures, primarily shaped by the first-committed enzyme, 2,3-oxidosqualene cyclases (OSCs) in plant triterpene biosynthesis. Triterpenes with B,C-ring-opened skeletons are extremely rare with unknown formation mechanisms, harbouring unchartered chemistry and biology. Here, through mining the genome of Chenopodium quinoa followed by functional characterization, we identified a stress-responsive and neofunctionalized OSC capable of generating B,C-ring-opened triterpenes, including camelliol A and B and the novel (-)-quinoxide A as wax components of the specialized epidermal bladder cells, namely the quinoxide synthase (CqQS). Protein structure analysis followed by site-directed mutagenesis identified key variable amino acid sites underlying functional interconversion between pentacyclic ß-amyrin synthase (CqbAS1) and B,C-ring-opened triterpene synthase CqQS. Mutation of one key residue (N612K) in even evolutionarily distant Arabidopsis ß-amyrin synthase could generate quinoxides, indicating a conserved mechanism for B,C-ring-opened triterpene formation in plants. Quantum computation combined with docking experiments further suggests that conformations of conserved W613 and F413 of CqQS might be key to selectively stabilizing intermediate carbocations towards B,C-ring-opened triterpene formation. Our findings shed light on quinoa triterpene skeletal diversity and mechanisms underlying B,C-ring-opened triterpene biosynthesis, opening avenues towards accessing their chemistry and biology and paving the way for quinoa trait engineering and quality improvement.

The Salinity Survival Strategy of Chenopodium quinoa: Investigating Microbial Community Shifts and Nitrogen Cycling in Saline Soils.

Quinoa is extensively cultivated for its nutritional value, and its exceptional capacity to endure elevated salt levels presents a promising resolution to the agricultural quandaries posed by salinity stress. However, limited research has been dedicated to elucidating the correlation between alterations in the salinity soil microbial community and nitrogen transformations. To scrutinize the underlying mechanisms behind quinoa's salt tolerance, we assessed the changes in microbial community structure and the abundance of nitrogen transformation genes across three distinct salinity thresholds (1 g·kg-1, 3 g·kg-1, and 6 g·kg-1) at two distinct time points (35 and 70 days). The results showed the positive effect of quinoa on the soil microbial community structure, including changes in key populations and its regulatory role in soil nitrogen cycling under salt stress. Choroflexi, Acidobacteriota, and Myxococcota were inhibited by increased salinity, while the relative abundance of Bacteroidota increased. Proteobacteria and Actinobacteria showed relatively stable abundances across time and salinity levels. Quinoa possesses the ability to synthesize or modify the composition of keystone species or promote the establishment of highly complex microbial networks (modularity index > 0.4) to cope with fluctuations in external salt stress environments. Furthermore, quinoa exhibited nitrogen (N) cycling by downregulating denitrification genes (nirS, nosZ), upregulating nitrification genes (Archaeal amoA (AOA), Bacterial amoA (AOB)), and stabilizing nitrogen fixation genes (nifH) to absorb nitrate-nitrogen (NO3-_N). This study paves the way for future research on regulating quinoa, promoting soil microbial communities, and nitrogen transformation in saline environments.

Evaluating relationships between seed morphological traits and seed dormancy in Chenopodium quinoa Willd.

Introduction: Quinoa is a high-value, nutritious crop that performs well in variable environments, marginal soils, and in diverse crop rotations. Quinoa's many attributes make it an ideal crop for supporting human health in global communities and economies. To date, quinoa research has largely focused on traits in adult plants important for enhancing plant phenotypic plasticity, abiotic stress, disease resistance, and yield. Fewer studies have evaluated quinoa seed dormancy and suggest that most modern quinoa varieties have weak or no seed dormancy, and a narrow window of seed viability post-harvest. In other crops, diminished seed dormancy is a major risk factor for preharvest sprouting (PHS; germination on the panicle due to rain prior to harvest) and may also pose a similar risk for quinoa. Methods: This study (1) developed a dormancy screening assay to characterize seed dormancy strength in a large collection of quinoa varieties, (2) investigated if morphological variables including seed coat color, seed coat thickness, seed shape including eccentricity which evaluates the roundness or flatness of a seed, and other agronomic traits like crude protein content and seed moisture, contribute to quinoa seed dormancy, and (3) evaluated the use of a phenetic modeling approach to explore relationships between seed morphology and seed dormancy. Results: Dormancy screening indicated seed dormancy ranges in quinoa varieties from none to strong dormancy. Further, phenetic modeling approaches indicate that seed coat thickness and eccentricity are important morphological variables that impact quinoa seed dormancy strength. Conclusions: While dormancy screening and phenetic modeling approaches do not provide a direct solution to preventing PHS in quinoa, they do provide new tools for identifying dormant varieties as well as morphological variables contributing to seed dormancy.

Identification of Reference Genes for Precise Expression Analysis during Germination in Chenopodium quinoa Seeds under Salt Stress.

Chenopodium quinoa Willd. (quinoa), a member of the Amaranthaceae family, is an allotetraploid annual plant, endemic to South America. The plant of C. quinoa presents significant ecological plasticity with exceptional adaptability to several environmental stresses, including salinity. The resilience of quinoa to several abiotic stresses, as well as its nutritional attributes, have led to significant shifts in quinoa cultivation worldwide over the past century. This work first defines germination sensu stricto in quinoa where the breakage of the pericarp and the testa is followed by endosperm rupture (ER). Transcriptomic changes in early seed germination stages lead to unstable expression levels in commonly used reference genes that are typically stable in vegetative tissues. Noteworthy, no suitable reference genes have been previously identified specifically for quinoa seed germination under salt stress conditions. This work aims to identify these genes as a prerequisite step for normalizing qPCR data. To this end, germinating seeds from UDEC2 and UDEC4 accessions, with different tolerance to salt, have been analyzed under conditions of absence (0 mM NaCl) and in the presence (250 mM NaCl) of sodium chloride. Based on the relevant literature, six candidate reference genes, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Monensin sensitivity1 (MON1), Polypyrimidine tract-binding protein (PTB), Actin-7 (ACT7), Ubiquitin-conjugating enzyme (UBC), and 18S ribosomal RNA (18S), were selected and assessed for stability using the RefFinder Tool encompassing the statistical algorithms geNorm, NormFinder, BestKeeper, and ΔCt in the evaluation. The data presented support the suitability of CqACT7 and CqUBC as reference genes for normalizing gene expression during seed germination under salinity stress. These recommended reference genes can be valuable tools for consistent qPCR studies on quinoa seeds.