Search Results (46)

Cadmium (Cd) contamination in agricultural soils poses a severe threat to food safety and human health through the food chain. This study investigated the efficacy of tobacco straw-derived biochar, applied at varying rates (0%, 1%, 2%, and 5% w/w), in mitigating Cd accumulation and modulating the growth and nutritional quality of two amaranth (Amaranthus tricolor L.) cultivars (red and green) grown in Cd-contaminated soil (initial total Cd of 2.18 mg/kg). The pot experiment revealed that biochar significantly reduced Cd uptake in both cultivars. Mechanistically, biochar elevated soil pH and drove the in-situ transformation of highly bioavailable exchangeable Cd into the more stable Fe-Mn oxide-bound fraction. Consequently, shoot Cd concentrations were notably suppressed, with the red cultivar exhibiting a superior response; the 2% biochar treatment optimally reduced its shoot Cd concentration by 37.6% compared to the control. Crucially, the amendments induced highly cultivar-specific growth responses. While biochar application simultaneously mitigated Cd toxicity and promoted biomass accumulation in red amaranth (yielding a 58.6% increase in shoot dry weight at the 2% rate), it exerted antagonistic, inhibitory effects on the growth of green amaranth. In conclusion, the incorporation of 2% tobacco straw biochar serves as a highly effective, dual-purpose strategy for significantly reduced health risks and enhancing the yield of red amaranth in Cd-contaminated fields. However, in green amaranth, biochar application induced a physiological trade-off, inhibiting growth despite successful Cd reduction. Furthermore, while Cd concentrations were significantly reduced on a dry-weight basis, future evaluations based on fresh-weight regulatory limits are required to fully confirm food safety. Full article

The impact of microplastic pollution on soil functions and the ecological toxicity to crops is a hotspot in agronomy and environmental science. In this study, a pot experiment was conducted to examine the effects of polyethylene microplastics (PE-MPs) at concentrations of 0.25%, 0.5%, 2.5%, and 5% on the growth, physiological indicators, soil physical and chemical properties, and soil bacterial community diversity of Amaranthus tricolor L. The results showed that adding PE-MPs inhibited the growth of A. tricolor L. stems and leaves, and as the dosage increased, the aboveground fresh weight decreased by 13.5% to 60.7%. At the same time, the chlorophyll content in A. tricolor L. leaves decreased, whereas the malondialdehyde (MDA) content increased by up to 11.8%. When the added dosage of PE-MPs was ≥0.5%, soil porosity and available phosphorus (AP) content significantly decreased, resulting in a significant reduction of 22.1% to 31.3% in the phosphorus content of the aboveground parts of A. tricolor L. compared with controls (CK). High-throughput sequencing results indicated that adding PE-MPs could reduce the Shannon index of the soil bacterial community and increase the Simpson index, suggesting a decrease in diversity. The addition of PE-MPs also altered the structure of the soil bacterial community, increasing the relative abundance of the Acidobacteriota, while the abundance of the Planctomycetota significantly decreased. This study provides a numerical and theoretical basis for evaluating the impact of microplastics on vegetable production and soil ecological environment effects. Full article

Squalene, a high-value triterpenoid precursor widely used in pharmaceuticals and vaccine adjuvants, is primarily sourced from shark liver oil—an unsustainable practice that has driven interest in developing plant-based production alternatives. The first committed reaction in triterpenoid biosynthesis is catalyzed by squalene synthase (SQS), yet no SQS gene has been characterized in Amaranthus tricolor, a species recognized for its high squalene content. Here, we cloned and functionally characterized AtrSQS, a novel squalene synthase gene isolated from A. tricolor for the first time. Sequence analysis revealed that AtrSQS contains conserved domains and six characteristic motifs shared among plant SQSs, with high homology to orthologs from dicotyledonous species. To investigate its functional role in squalene biosynthesis, AtrSQS was overexpressed in Nicotiana tabacum under the CaMV 35S promoter. Transgenic lines exhibited significantly increased AtrSQS expression and accumulated squalene up to 6.81 μg/g dry weight, a 4.76-fold increase over wild-type plants. Additionally, the content of downstream product 2,3-oxidosqualene was also significantly elevated in the transgenic lines. Integrated transcriptomic and metabolomic analyses revealed that AtrSQS overexpression upregulated key mevalonate pathway genes (AACT, HMGS, MVD) and FPPS. Meanwhile, it suppressed competitive carotenoid biosynthesis and the production of an SQS-specific inhibitor, indicating a successful redirection of metabolic flux toward squalene production. These findings demonstrate that AtrSQS is crucial for squalene biosynthesis and provide both a valuable genetic resource and mechanistic insights for engineering plant-based squalene production systems. Full article

Amaranth (Amaranthus spp.) is a multifaceted genus of C4 plants with significant nutritional and agronomic potential, yet it remains underutilized in mainstream agriculture. Despite growing interest in Amaranth, most germplasm studies have used either phenotypic or molecular approaches alone, lacking integration. Multivariate methods have not been systematically applied to identify promising genotypes, and species-specific selection indices for grain Amaranth remain unexplored. To address these gaps, this study comprehensively characterized 84 Amaranth genotypes representing multiple species (A. caudatus, A. cruentus, A. hypochondriacus, A. hybridus, A. spinosus, A. powellii, A. tricolor, and 38 accessions of unknown taxonomic status) using field experiments in a randomized complete block design with three replications and DNA barcoding with chloroplast (psbA-trnH) and nuclear (ITS) markers. Analysis of variance revealed highly significant differences (p < 0.01) among genotypes for all six agronomic traits evaluated, confirming substantial genetic variability with grain yield exhibiting the widest variation (CV = 28.55%), ranging from 0.25 to 125.56 g/plant. High broad-sense heritability estimates (0.79–0.99) coupled with high genetic advance, particularly for grain yield (117.54%), indicated that these traits would respond favorably to selection. Path analysis and stepwise regression identified early flowering, long inflorescences, and heavy seeds as the primary determinants of grain yield, collectively explaining 27% of yield variation. Mahalanobis D² analysis identified nine multivariate outliers with distinct phenotypic profiles, among which G39 emerged as the most promising breeding candidate, combining exceptional yield (90.50 g/plant) with desirable architecture, long inflorescence, and large seeds. Principal component analysis further resolved trait complexes, identifying 11 PC1-selected promising genotypes as donors for plant architecture and three PC2-selected promising genotypes as donors for seed size characteristics. Molecular analysis revealed distinct genetic relationships. A. caudatus (kiwicha) exhibited limited haplotype diversity indicating a narrow genetic base, while A. cruentus and A. hypochondriacus showed broader diversity, with the nuclear ITS network providing clearer resolution than chloroplast markers due to biparental inheritance. Outlier genotypes, including G82, G83, G13, G10, and G39, occupied unique haplotype positions, confirming that their phenotypic distinctiveness corresponds to genuine genetic differentiation. The novelty of this study lies in integrating multivariate biostatistical techniques (heritability, path analysis, Mahalanobis D², PCA, and stepwise regression) with two complementary DNA barcode systems (chloroplast and nuclear) within a single germplasm collection. This integrated approach provides breeders with well-characterized germplasm, validated selection criteria, and prioritized parental materials for Amaranth improvement. Further multi-location and multi-season evaluations are recommended to ensure the stability and adaptability of these promising germplasm accessions. Full article

Weeds are a major cause of crop production losses worldwide, and environmentally friendly chemical control based on natural or semisynthetic compounds has attracted increasing attention. In this study, flavokawains, a class of natural chalcones, and their analogues were converted into dihydrochalcones (1–27) via Pd-catalyzed hydrogenation. The herbicidal activities of these compounds were evaluated against Chinese amaranth (Amaranthus tricolor) and barnyard grass (Echinochloa crus-galli). Several compounds significantly inhibited seed germination and seedling growth in both species. Herbicidal activity was strongly influenced by the type and position of aromatic substituents, with electron-withdrawing groups and meta substitution providing higher activity. The meta-chloro derivative (15) exhibited the highest activity, markedly inhibiting seed germination as well as shoot and root growth. Further investigation of its mode of action revealed that this compound interfered with seed imbibition, inhibited α-amylase activity, and affected membrane integrity and malondialdehyde (MDA) levels in A. tricolor in a concentration-dependent manner. These findings provide valuable insights for the development of natural product-derived herbicides. Full article

Artificial lighting is a central and resource-intensive component of controlled environment agriculture, directly regulating plant physiological processes while influencing energy efficiency and production outcomes. Chlorophyll fluorescence analysis, particularly pulse-amplitude-modulated fluorometry, provides a rapid and non-destructive method for assessing plants’ photosynthetic efficiency. However, the extent to which chlorophyll fluorescence reflects plant responses to different light spectra across species remains insufficiently understood. In this study, species-specific photoresponses of leafy vegetables (Amaranthus tricolor, Barbarea verna, Chrysanthemum coronarium, Perilla frutescens) to different light spectra were investigated by integrating chlorophyll fluorescence with growth, antioxidant, and pigment traits. Plants were cultivated under monochromatic red, blue, and combined red–blue light, with additional far-red supplementation. Correlation analysis was performed among growth, antioxidant parameters, pigment contents, and chlorophyll fluorescence parameters. The obtained results show that chlorophyll fluorescence parameters respond selectively, but species-specifically, to applied lighting-spectrum conditions. Relationships between fluorescence indices and physiological traits varied between species, and no single parameter consistently reflected plant performance across all crops. Therefore, to employ chlorophyll fluorescence as a useful proxy for assessing plant responses to lighting spectrum, a species-specific and context-dependent approach is required. Full article

Amaranthus L. includes valuable and promising crops of multi-purpose use, having high morphological diversity and complicated taxonomy. Their karyotypes and genomic relationships remain insufficiently studied. For the first time, a comparative repeatome analysis of Amaranthus tricolor L., Amaranthus cruentus L., and Amaranthus hypochondriacus L. was performed based on the high-throughput sequencing data obtained via bioinformatic analyses using the RepeatExplorer2/TAREAN/DANTE_LTR pipelines. Interspecific variations in the abundance of Ty1 Copia and Ty3 Gypsy retroelements, DNA transposons, and ribosomal and satellite DNA (satDNA) were detected. Based on fluorescence in situ hybridization (FISH), chromosome mapping of 45S rDNA, 5S rDNA, and satDNAs AmC9 and AmC70, and unique karyograms of A. tricolor, A. cruentus, Amaranthus paniculatus L., and A. hypochondriacus were constructed. The analysis of the interspecies genome diversity/similarity in DNA repeat contents, sequences of the identified satDNAs, and chromosome distribution patterns of the studied molecular markers indicated that these species might also share a common evolutionary ancestor. However, the genomes of A. cruentus, A. paniculatus, and A. hypochondriacus were more similar compared to A. tricolor, which aligns with the previous phylogenetic data. Our results demonstrate that cytogenomic studies might provide important data on Amaranthus species relationships elucidating taxonomy and evolution of these valuable crops. Full article

The present experiment aimed to examine the impact of nano urea (NU) and plant growth-promoting rhizobacteria (PGPR) on Reshmi amaranth (Amaranthus tricolor) growth under salt stress. Experiments were conducted using six different combinations of NaCl, NU, and PGPR for 35 days under greenhouse conditions. The results showed that salinity stress significantly (p < 0.05) reduced plant growth parameters, including shoot height, root length, fresh weight, and leaf area. However, the application of NU and PGPR, both individually and in combination, enhanced plant growth and physiological resilience under saline conditions. The NU + PGPR treatment yielded the best improvements, with a shoot height of 42.25 cm, root length of 34.79 cm, and fresh weight of 61.69 g, indicating a synergistic effect. Biochemical analysis showed that NaCl stress lowered chlorophyll (0.25 mg/g fwt.) and carotenoids (60.17 µg/100 g) and disrupted ionic homeostasis by increasing Na⁺ accumulation while reducing K⁺ and Ca²⁺ uptake. The combined NU and PGPR treatment restored ionic balance, with Na⁺ reduced to 58.12 mg and K⁺ and Ca²⁺ levels increasing to 115.25 mg and 78.70 mg, respectively. Stress markers such as malondialdehyde (MDA) and proline also showed significant reductions, while antioxidant enzyme activities stabilized under NU and PGPR application. Thus, this study indicated that NU and PGPR mitigate salt-induced stress by improving nutrient assimilation, promoting osmotic regulation, and enhancing antioxidative defenses in Reshmi amaranth. Full article

Light intensity and spectral composition are the main parameters that may be modulated to further affect plant nutritional value and shelf life. The current study aimed to assess how variations in spectral composition and light intensity affect sugar accumulation during the storage of two popular microgreens cultivated in a greenhouse under controlled conditions. Thus, in this study, amaranth (Amaranthus tricolor) and mustard (Brassica juncea) microgreens were grown in a greenhouse at 17/20 ± 3 °C and a 16 h photoperiod was maintained. (I) Four LED light intensities were set: 100, 150, 200, and 250 µmol m⁻² s⁻¹ while using 4000 K white LED lighting. (II) Maintaining 250 µmol m⁻² s⁻¹ the effect of spectrac composition: B_75.6%:R_24.2%:W_0.02%/R_88.9%:B_11.1%/and R_77.6%:W_9.9%:B_3.5% was evaluated. After 10 days from germination, microgreens were harvested and stored in the dark or under white LED light at +4 °C. Samples were collected on D₀, D₁, D₃, and D₅ days of postharvest storage. The results revealed that a wide spectrum of 250 µmol m⁻² s⁻¹ PPFD and R_88.9%:B_11.1% growing conditions produced the highest sugar content, achieving a balance between increased sugar accumulation and reduced deterioration during storage, ultimately extending shelf life. Full article

Betalains differ from anthocyanins, and they cannot coexist in the same plant under natural conditions. The L-DOPA 4,5-dioxygenase encoded by the DODA gene is a key step in the pathway of betalain biosynthesis in Caryophyllales plants. Amaranth is an important resource for the study and extraction of betalains. In order to clarify the function of AtrDODA family genes in betalain biosynthesis, we screened out three AtrDODA family gene members associated with betalains based on a genome database and RNA-seq databases of Amaranthus tricolor. Their characterization and expression pattern were further analyzed. The result of subcellular localization showed that all three AtrDODA members were located in the nucleus. Betacyanin and betaxanthin were promoted by paclobutrazol treatment in the leaves and stems of ‘Suxian No.1’ (red), while they were inhibited by gibberellin and darkness, which were consistent with the gene expression pattern of AtrDODAs. After heterologous transformation of the AtrDODA1-1 promoter into tobacco with GUS staining analysis, the promoter activity of AtrDODA1-1 of ‘Suxian No.1’ (red) amaranth was significantly higher than that of ‘Suxian No.2’ (green) amaranth. Furthermore, we analyzed the promoter activity of AtrDODA1-1 by GUS staining and qRT-PCR after sprayed exogenous MeJA and GA₃ on the AtrDODA1-1 promoter transformed tobacco plants. The results showed that AtrDODA1-1 responded to plant hormones. This study could lay a foundation for revealing the biological functions of the amaranth DODA gene family, and provide new clues for the molecular mechanism of betalain synthesis. Full article

MYB (myeloblastosis) is one of the most abundant transcription factors in plants which regulates various biological processes. The molecular characteristics and function of R2R3-MYB transcription factors in amaranth remain unclear. In this study, 73 R2R3-MYB members were identified from the amaranth genome database and we further analyzed their chromosome position, conserved motifs, physiological and biochemical features, collinearity relationships, gene structure, phylogeny and cis-acting element. Based on the phylogenetic and expression pattern analysis, 14 candidate R2R3-MYB genes might be involved in the betalain synthesis. Amongst the 14 candidate R2R3-MYB genes, the expression level of AtrMYB72 was higher in ‘Suxian No.1’ than ‘Suxian No.2’, and also higher in the red section than in the green section of the same leaf in Amaranthus. The overexpression vector pCambia1301-AtrMYB72-GUS and VIGS (virus-induced gene silencing) vector pTRV2- AtrMYB72 were transferred into leaves of ‘Suxian No.1’ via an Agrobacterium-mediated method. The results showed that AtrMYB72 overexpression could promote betalain synthesis. A yeast one-hybrid assay and dual luciferase reporter gene assay demonstrated that AtrMYB72 could bind to the AtrCYP76AD1 promoter to promote betalain synthesis. These results indicated that AtrMYB72 promoted betalain biosynthesis in amaranth by activating the AtrCYP76AD1 transcription. Our results could provide new insights into the betalain biosynthesis in amaranth. Full article

Drought may facilitate the invasion process of invasive plants, mainly because invasive plants can obtain a stronger growth competitiveness than native plants under drought. It is therefore imperative to illuminate the mechanisms underlying the successful invasion of invasive plants under drought, with a particular focus on the differences in the resistance of invasive and native plants to drought. This study aimed to elucidate the differences in the resistance between the invasive plant Amaranthus spinosus L. and the native plant A. tricolor L. to drought under a gradient of drought. The resistance of co-cultivated A. spinosus to drought was significantly higher than that of co-cultivated A. tricolor under light drought. Hence, A. spinosus may obtain a stronger competitive advantage than A. spinosus under co-cultivation conditions when treated with light drought. The resistance of the two plants to drought may be predominantly influenced by their height and biomass. This present study also defines a method for evaluating the stress resistance of a given plant species to stress by calculating the stress resistance index. This present study offers a robust theoretical foundation for determining the stress resistance of a given plant species and the environmental management of A. spinosus under drought. Full article

To explore and utilize the abundant soil microorganisms and their beneficial functions, high-throughput sequencing technology was used to analyze soil microbial compositions in the rhizosphere of red and green amaranth varieties. The results showed that significant differences in soil microbial composition could be found in the rhizosphere of amaranth plants with different color phenotypes. Firstly, soil bacterial compositions in the rhizosphere were significantly different between red and green amaranths. Among them, Streptomyces, Pseudonocardia, Pseudolabrys, Acidibacter, norank_ f_ Micropepsaceae, Bradyrhizobium, and Nocardioides were the unique dominant soil bacterial genera in the rhizosphere of red amaranth. In contrast, Conexibacter, norank_f_norank_o_norank_c_TK10, and norank_f_ norank_o_ norank_ c_AD3 were the special dominant soil bacterial genera in the rhizosphere of green amaranth. Additionally, even though the soil fungal compositions in the rhizosphere were not significantly different between red and green amaranths, the abundance of the dominant soil fungal genera in the rhizosphere showed significant differences between red and green amaranths. For example, unclassified_k__Fungi, Fusarium, Cladophialophora, unclassified_c__Sordariomycetes and unclassified_p__Chytridiomycota significantly enriched as the dominant soil fungal genera in the rhizosphere of the red amaranth. In contrast, Aspergillues only significantly enriched as the dominant soil fungal genus in the rhizosphere of green amaranth. All of the above results indicated that amaranth with various color phenotypes exactly recruited different microorganisms in rhizosphere, and the enrichments of soil microorganisms in the rhizosphere could be speculated in contributing to amaranth color formations. Full article

Nitrate leaching, greenhouse gas emissions, and water loss are caused by conventional water and fertilizer management in vegetable fields. The Expert-N system is a useful tool for recommending the optimal nitrogen (N) fertilizer for vegetable cultivation. To clarify the fates of water and N in vegetable fields, an open-field vegetable cultivation experiment was conducted in Dongbeiwang, Beijing. This experiment tested two irrigation treatments (W1: conventional and W2: optimal) and three fertilizer treatments (N1: conventional, N2: optimal N rate by Expert-N system, and N3: 80% optimal N rate) on cauliflower (Brassica oleracea L.), amaranth (Amaranthus tricolor L.), and spinach (Spinacia oleracea L.). The EU-Rotate_N model was used to simulate the fates of water and N in the soil. The results indicated that the yields of amaranth and spinach showed no significant differences among all the treatments in 2000 and 2001. However, cauliflower yield under the W1N2 and W1N3 treatments obviously reduced in 2001. Compared with the W1 treatment, W2 reduced irrigation amount by 27.9–29.8%, water drainage by over 76%, increased water use efficiency by 5–17%, and irrigation water use efficiency by 29–45%. Nitrate leaching was one of the main pathways in this study, accounting for 8.4% of the total N input; compared to N1, the input of fertilizer N under the N2 and N3 treatments decreased by over 66.5%, consequently reducing gaseous N by 48–72% and increasing nitrogen use efficiency (NUE) by 17–37%. Additionally, compared with the W1 treatments, gaseous N loss under the W2 treatments was reduced by 18–26% and annual average NUEs increased by 22–29%. The highest annual average NUEs were under W2N3 (169.6 kg kg⁻¹) in 2000 and W2N2 (188.0 kg kg⁻¹) in 2001, respectively. We found that optimizing fertilizer management allowed subsequent crops to utilize residual N in the soil. Therefore, we suggest that the W2N3 management should be recommended to farmers to reduce water and N loss in vegetable production systems. Full article

Amaranthus tricolor is an important vegetable, and its quality is affected by salt stress. Cation/proton antiporters (CPA) contribute to plant development and tolerance to salt stress. In this study, 35 CPA genes were identified from a genome database for A. tricolor, including 9 NHX, 5 KEA, and 21 CPA2 genes. Furthermore, in A. tricolor, the expression levels of most AtrNHX genes were higher at a low salinity level (50 or 100 mM NaCl) than in the control or 200 mM NaCl treatment. Levels of most AtrNHX genes were elevated in the stem. Moreover, AtrNHX8 was homologous to AtNHX4, which is involved in the regulation of sodium homeostasis and salt stress response. After AtrNHX8 overexpression in Arabidopsis thaliana, seed germination was better, and the flowering time was earlier than that of wild-type plants. Additionally, the overexpression of AtrNHX8 in A. thaliana improved salt tolerance. These results reveal the roles of AtrNHX genes under salt stress and provide valuable information on this gene family in amaranth. Full article