Nucleic Acid-Based Nanodevices in Biological Imaging.

The nanoscale engineering of nucleic acids has led to exciting molecular technologies for high-end biological imaging. The predictable base pairing, high programmability, and superior new chemical and biological methods used to access nucleic acids with diverse lengths and in high purity, coupled with computational tools for their design, have allowed the creation of a stunning diversity of nucleic acid-based nanodevices. Given their biological origin, such synthetic devices have a tremendous capacity to interface with the biological world, and this capacity lies at the heart of several nucleic acid-based technologies that are finding applications in biological systems. We discuss these diverse applications and emphasize the advantage, in terms of physicochemical properties, that the nucleic acid scaffold brings to these contexts. As our ability to engineer this versatile scaffold increases, its applications in structural, cellular, and organismal biology are clearly poised to massively expand.

Gibberellins regulate masculinization through the SpGAI-SpSTM module in dioecious spinach.

The sex of dioecious plants is mainly determined by genetic factors, but it can also be converted by environmental cues such as exogenous phytohormones. Gibberellic acids (GAs) are well-known inducers of flowering and sexual development, yet the pathway of gibberellin-induced sex conversion in dioecious spinach (Spinacia oleracea L.) remains elusive. Based on sex detection before and after GA3 application using T11A and SSR19 molecular markers, we confirmed and elevated the masculinization effect of GA on a single female plant through exogenous applications of GA3, showing complete conversion and functional stamens. Silencing of GIBBERELLIC ACID INSENSITIVE (SpGAI), a single DELLA family protein that is a central GA signaling repressor, results in similar masculinization. We also show that SpGAI can physically interact with the spinach KNOX transcription factor SHOOT MERISTEMLESS (SpSTM), which is a homolog of the flower meristem identity regulator STM in Arabidopsis. The silencing of SpSTM also masculinized female flowers in spinach. Furthermore, SpSTM could directly bind the intron of SpPI to repress SpPI expression in developing female flowers. Overall, our results suggest that GA induces a female masculinization process through the SpGAI-SpSTM-SpPI regulatory module in spinach. These insights may help to clarify the molecular mechanism underlying the sex conversion system in dioecious plants while also elucidating the physiological basis for the generation of unisexual flowers so as to establish dioecy in plants.

Genome-wide characterization, functional analysis, and expression profiling of the Aux/IAA gene family in spinach.

BACKGROUND: The auxin/indole-3-acetic acid (Aux/IAA) gene family is a crucial element of the auxin signaling pathway, significantly influencing plant growth and development. Hence, we conducted a comprehensive investigation of Aux/IAAs gene family using the Sp75 and Monoe-Viroflay genomes in spinach. RESULTS: A total of 24 definitive Aux/IAA genes were identified, exhibiting diverse attributes in terms of amino acid length, molecular weight, and isoelectric points. This diversity underscores potential specific roles within the family, such as growth regulation and stress response. Structural analysis revealed significant variations in gene length and molecular weight. These variations indicate distinct roles within the Aux/IAA gene family. Chromosomal distribution analysis exhibited a dispersed pattern, with chromosomes 4 and 1 hosting the highest and lowest numbers of Aux/IAA genes, respectively. Phylogenetic analysis grouped the identified genes into distinct clades, revealing potential evolutionary relationships. Notably, the phylogenetic tree highlighted specific gene clusters suggesting shared genetic ancestry and potential functional synergies within spinach. Expression analysis under NAA treatment unveiled gene-specific and time-dependent responses, with certain genes exhibiting distinct temporal expression patterns. Specifically, SpoIAA5 displayed a substantial increase at 2 h post-NAA treatment, while SpoIAA7 and SpoIAA9 demonstrated continuous rises, peaking at the 4-hour time point. CONCLUSIONS: These observations indicate a complex interplay of gene-specific and temporal regulation in response to auxin. Moreover, the comparison with other plant species emphasized both shared characteristics and unique features in Aux/IAA gene numbers, providing insights into the evolutionary dynamics of this gene family. This comprehensive characterization of Aux/IAA genes in spinach not only establishes the foundation for understanding their specific functions in spinach development but also provides a valuable resource for experimental validation and further exploration of their roles in the intricate network of auxin signaling pathways.

Quantitative Analysis of 2D EXSY NMR Spectra of Strongly Coupled Spin Systems in Transmembrane Exchange.

Solute translocation by membrane transport proteins is a vital biological process that can be tracked, on the sub-second timescale, using nuclear magnetic resonance (NMR). Fluorinated substrate analogues facilitate such studies because of high sensitivity of 19 F NMR and absence of background signals. Accurate extraction of translocation rate constants requires precise quantification of NMR signal intensities. This becomes complicated in the presence of J-couplings, cross-correlations, and nuclear Overhauser effects (NOE) that alter signal integrals through mechanisms unrelated to translocation. Geminal difluorinated motifs introduce strong and hard-to-quantify contributions from non-exchange effects, the nuanced nature of which makes them hard to integrate into data analysis methodologies. With analytical expressions not being available, numerical least squares fitting of theoretical models to 2D spectra emerges as the preferred quantification approach. For large spin systems with simultaneous coherent evolution, cross-relaxation, cross-correlation, conformational exchange, and membrane translocation between compartments with different viscosities, the only available simulation framework is Spinach. In this study, we demonstrate GLUT-1 dependent membrane transport of two model sugars featuring CF2 and CF2 CF2 fluorination motifs, with precise determination of translocation rate constants enabled by numerical fitting of 2D EXSY spectra. For spin systems and kinetic networks of this complexity, this was not previously tractable.

Ligands with polyfluorophenyl moieties promote a local structural rearrangement in the Spinach2 and Broccoli aptamers that increases ligand affinities.

The interaction of nucleic acids with their molecular targets often involves structural reorganization that may traverse a complex folding landscape. With the more recent recognition that many RNAs, both coding and noncoding, may regulate cellular activities by interacting with target molecules, it becomes increasingly important to understand how nucleic acids interact with their targets and how drugs might be developed that can influence critical folding transitions. We have extensively investigated the interaction of the Spinach2 and Broccoli aptamers with a library of small molecule ligands modified by various extensions from the imido nitrogen of DFHBI [(Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one] that reach out from the Spinach2 ligand binding pocket. Studies of the interaction of these compounds with the aptamers revealed that polyfluorophenyl-modified ligands initiate a slow change in aptamer affinity that takes an extended time (half-life of ∼40 min) to achieve. The change in affinity appears to involve an initial disruption of the entrance to the ligand binding pocket followed by a gradual transition to a more defined structure for which the most likely driving force is an interaction of the gateway adenine with a nearby 2'OH group. These results suggest that polyfluorophenyl modifications might increase the ability of small molecule drugs to disrupt local structure and promote RNA remodeling.

A longitudinal study on the bacterial quality of baby spinach cultivated in Arizona and California.

In the U.S., baby spinach is mostly produced in Arizona (AZ) and California (CA). Characterizing the impact of growing region on the bacterial quality of baby spinach can inform quality management practices in industry. Between December 2021 and December 2022, baby spinach was sampled after harvest and packaging for microbiological testing, including shelf-life testing of packaged samples that were stored at 4°C. Samples were tested to (i) determine bacterial concentration, and (ii) obtain and identify bacterial isolates. Packaged samples from the Salinas, CA, area (n = 13), compared to those from the Yuma, AZ, area (n = 9), had a significantly higher bacterial concentration, on average, by 0.78 log10 CFU/g (P < 0.01, based on aerobic, mesophilic plate count data) or 0.67 log10 CFU/g (P < 0.01, based on psychrotolerant plate count data); the bacterial concentrations of harvest samples from the Yuma and Salinas areas were not significantly different. Our data also support that an increase in preharvest temperature is significantly associated with an increase in the bacterial concentration on harvested and packaged spinach. A Fisher's exact test and linear discriminant analysis (effect size), respectively, demonstrated that (i) the genera of 2,186 bacterial isolates were associated (P < 0.01) with growing region and (ii) Pseudomonas spp. and Exiguobacterium spp. were enriched in spinach from the Yuma and Salinas areas, respectively. Our findings provide preliminary evidence that growing region and preharvest temperature may impact the bacterial quality of spinach and thus could inform more targeted strategies to manage produce quality. IMPORTANCE: In the U.S., most spinach is produced in Arizona (AZ) and California (CA) seasonally; typically, spinach is cultivated in the Yuma, AZ, area during the winter and in the Salinas, CA, area during the summer. As the bacterial quality of baby spinach can influence consumer acceptance of the product, it is important to assess whether the bacterial quality of baby spinach can vary between spinach-growing regions. The findings of this study provide insights that could be used to support region-specific quality management strategies for baby spinach. Our results also highlight the value of further evaluating the impact of growing region and preharvest temperature on the bacterial quality of different produce commodities.

Insights into spinach domestication from genome sequences of two wild spinach progenitors, Spinacia turkestanica and Spinacia tetrandra.

Cultivated spinach (Spinacia oleracea) is a dioecious species. We report high-quality genome sequences for its two closest wild relatives, Spinacia turkestanica and Spinacia tetrandra, which are also dioecious, and are used to study the genetics of spinach domestication. Using a combination of genomic approaches, we assembled genomes of both these species and analyzed them in comparison with the previously assembled S. oleracea genome. These species diverged c. 6.3 million years ago (Ma), while cultivated spinach split from S. turkestanica 0.8 Ma. In all three species, all six chromosomes include very large gene-poor, repeat-rich regions, which, in S. oleracea, are pericentromeric regions with very low recombination rates in both male and female genetic maps. We describe population genomic evidence that the similar regions in the wild species also recombine rarely. We characterized 282 structural variants (SVs) that have been selected during domestication. These regions include genes associated with leaf margin type and flowering time. We also describe evidence that the downy mildew resistance loci of cultivated spinach are derived from introgression from both wild spinach species. Collectively, this study reveals the genome architecture of spinach assemblies and highlights the importance of SVs during the domestication of cultivated spinach.

The presence of free palmitic acid modulates the effects of lutein on structural and dynamic properties of lipid membranes.

Free fatty acids, like palmitic acid (PA), and xanthophyll pigments, like lutein (LUT) are the natural membrane compounds in plants. To study the effect of PA on LUT and their organization, a model membrane of 1,2-dimyristoyl-sn-glycerol-3-phosphocholine (DMPC) enriched with 2 mol% PA and 1 mol% LUT was formed. Molecular mechanisms underlying the interaction between these two compounds were examined with application of molecular spectroscopy techniques, e.g., visible spectroscopy, electron paramagnetic resonance and Fourier transform infrared. We determined the monomeric/dimeric organization of LUT in the membrane. We proved that the presence of PA in the lipid phase facilitated and stabilized the formation of LUT structures in the membrane. Lutein with PA did not form strong molecular aggregates like H- and J-structures. We presented the simplified model membrane that could be a suitable representation of the physiological process of de-esterification of PA from LUT appearing in natural biomembranes in humans.

Effects of dietary nitrate supplementation on oral health and associated markers of systemic health: a systematic review.

Poor oral health can impact an individual's ability to eat and has been associated with an increased risk of non-communicable diseases. While the benefits of nitrate consumption on oral health were first proposed more than 20 years ago, no systematic review has been published examining effects of dietary nitrate on oral health. This systematic review investigated the effects of dietary nitrate on markers of oral health in vivo in randomized controlled trials (RCTs). Five databases (PubMed, The Cochrane Library, CINAHL, MEDLINE, and SPORTDiscus) were searched from inception until March 2023. Nine articles reporting data on 284 participants were included. Dietary nitrate was provided via beetroot juice in most studies. The duration of the interventions ranged from one day to six weeks. Dietary nitrate supplementation increased the relative abundance of several individual bacterial genera including Neisseria and Rothia. Dietary nitrate supplementation increased salivary pH and decreased salivary acidification following consumption of a sugar-sweetened beverage. Furthermore, dietary nitrate supplementation resulted in a decrease in the gingival inflammation index. The results of this systematic review suggest that dietary nitrate could represent a potential nutritional strategy to positively modify oral health by impacting the oral microbiome, altering salivary pH, and minimizing gingival inflammation.

Plant growth-promoting bacteria isolated from earthworms enhance spinach growth and its phytoremediation potential in metal-contaminated soils.

The aim of this study was to evaluate the impact of metal-tolerant plant growth-promoting bacteria (PGPB) isolated from the chloragogenous tissue of Aporrectodea molleri, which represents a unique habitat. Our objectives were to investigate their effects on the growth of Spinacia oleracea under heavy metal stress and assess their potential for enhancing phytoremediation capabilities. The experiment was conducted in an alkaline soil contaminated with 7 mg kg-1 of cadmium, 100 mg kg-1 of nickel, 150 mg kg-1 of copper, 300 mg kg-1 of Zinc, and mg kg-1 of 600 Manganese. The results showed that heavy metal stress considerably diminished root (42.8%) and shoot length (60.1%), biomass (80%), chlorophyll content (41%), soil alkaline (45%), and acid (51%) phosphatases (42%) and urease (42%). However, soil inoculation with bacterial isolates remarkably improved plant growth. Soil bioaugmentation increased spinach growth (up to 74.5% for root length, up to 106.3% for shoot length, and up to 5.5 folds for fresh biomass) while significantly increasing soil enzyme activity and NPK content. Multivariate data analysis indicated that soil inoculation with Bacillus circulans TC7 promoted plant growth while limiting metal bioaccumulation, whereas Pseudomonas sp. TC33 and Bacillus subtilis TC34 increased metal bioaccumulation in spinach tissues while minimizing their toxicity. Our study confirms that earthworms are a reservoir of multi-beneficial bacteria that can effectively improve phytoremediation efficiency and mitigate the toxic effects of heavy metals on plant growth. Further studies are needed to investigate the long-term effects and feasibility of using these isolates as a consortium in field applications.

Health risks assessment and source admeasurement of potentially dangerous heavy metals (Cu, Fe, and Ni) in rapidly growing urban settlement.

Environmental contamination is a global challenge that impacts every aspect of ecosystem. The contaminants from anthropogenic or industrial trash continually recirculate into the environment, agricultural land, plants, livestock, and ultimately into humans by way of the food chain. After an increase in human and farmland animal deaths from illnesses due to contaminated drinking water, toxic metal water poisoning has remained a global concern. Diverse environmental and enforcement organisations have attempted to regulate the activities that serve as precursors to these heavy metals which have been proven ineffective. These unnecessary metals have severely hampered most biological processes. The presence of hazardous metals, which are harmful at extremely high levels and have a negative effect on the health of living bodies generally degrades the nutritional value of water. In order to evaluate the heavy metals (Cu, Ni, and Fe) toxicity of groundwater in pri-urban areas, the current study was conducted that have been considered as advance solution to tackle climate change which influence coastal ecosystem. Additionally, the impacts of soil and plant (spinach and brassica) contamination from groundwater were evaluated. The heavy metals were examined in the soil and groundwater samples (Pb, Fe and Ni). While Fe concentrations in water samples were found to be high as 1.978 mg/L as compared to Ni and Cu values low. According to WHO guidelines, the mean value of Fe exceeds the limit value. Similarly, Cu had a higher mean value (0.7 mg/L) in soil samples than other metals (Ni and Fe). In comparison to Ni and Cu, the Fe concentrations in spinach and brassica plants samples are greater, at 17.2 mg/L and 3.22 mg/L, respectively. The possible effects of metal poisoning of groundwater and plants on human health have been assessed using the Hazard Quotient (HQ), Evaluated Daily Intake (EDI), and Incremental Life Time Cancer Risk formulas (ILTCR). When drinking Ni-contaminated water, humans are more at risk of developing cancer (0.0031) than Fe and Cu. Metal concentrations in water and brassica showed substantially more scattered behaviour on the plot and no meaningful relationship, although PCA and masked matrix correlation showed a fair association between Ni and Cu in brassica (r2: 0.46) and Fe and Ni in spinach (r2: 0.31). According to the study's findings, it is anticipated that special management and groundwater monitoring will be needed in the examined area to reduce the health risks related to drinking water that has been contaminated with metals.

Assessing global-warming induced soil organic matter and iron oxides depletion: Empirical insights into sorption and uptake of atrazine by plants.

Recent pesticide use is alarmingly high and unregulated in several parts of the world. Pesticide fate in soil is controlled by sorption processes which affect the subsequent transport and chemical reactivity in the environment, as well as uptake by plants. Sorption processes are dependent on soil composition and properties, but these are beginning to be affected by global warming-linked factors leading to soil depletion. Thus, it is vital to decipher soils' response, especially in the sub-Sahara (SS), to the depletion of some inherent components in the presence of pesticides. This was ascertained by monitoring a model pesticide (atrazine) sorption and desorption on whole SS soil (WS), and the same soil whose organic matter (OMR) and iron oxides (IOR) were substantially depleted, as well as studying atrazine uptake from these soils by fast-growing vegetables. Organic matter depletion enhanced equilibrium in OMR. Sorption was enhanced at lower ambient pH, higher initial atrazine concentration, and higher temperature. Hysteresis was low resulting in high desorption. Overall, atrazine desorption of ≥65 % was observed; it was higher in OMR (≥95 %) since SOM enhanced hysteresis. Though sub-Saharan soils are rich in iron oxides, SOM played a significantly higher role in sorption than iron oxides in this soil. This result suggests a high potential for atrazine to leach into the aquifer in the sub-Saharan. Atrazine uptake experiment by waterleaf and spinach showed that it could be detected in soil after 63 d, and its presence significantly affected the growth of both vegetables especially in soils with depleted SOM and iron oxides, and at high (100 µg/kg) atrazine spiking. Spinach may be a higher atrazine accumulator than waterleaf. It may be concluded that waterleaf and spinach grown on atrazine-contaminated soils, especially on SOM/iron oxide-depleted soils, are likely to accumulate atrazine.

Microwave synthesized novel biomass carbon dots applied in the fluorescent detection of crystal violet.

To establish a new method for detecting crystal violet (CV), a harmful dye, herein, a genre of novel biomass carbon dots (CDs) was synthesized via a microwave method and employed as a fluorescent probe, in which water spinach and polyethylene glycol (PEG) performed as raw materials. Based on the inner filter effect (IFE) between the luminescent CDs and CV, the blue emission of this probe at 430 nm could be quenched by CV. Hence, a new strategy was proposed to selectively determine CV in aquaculture ambient. Moreover, under the optimal experiment conditions, this method showed a good linearity between the concentration of CV (c) and fluorescence quenching rate (ΔF/F0) in the concentration range of 4-200 µmol/L with the corresponding correlation coefficient (r) and the detection limit of 0.997 and 710 nmol/L, respectively. With advantages of environmental protectivity, sensitivity, affordability, and user-friendliness, the facilely fabricated CDs could be successfully applied in detecting CV in aquaculture samples, providing a technical foundation for monitoring the pollution of CV and ensuring the quality and safety of aquatic products.

Transmission of Spinach Downy Mildew via Seed and Infested Leaf Debris.

Spinach downy mildew, caused by the obligate oomycete pathogen Peronospora effusa, is a worldwide constraint on spinach production. The role of airborne sporangia in the disease cycle of P. effusa is well established, but the role of the sexual oospores in the epidemiology of P. effusa is less clear and has been a major challenge to examine experimentally. To evaluate seed transmission of spinach downy mildew via oospores in this study, isolated glass chambers were employed in two independent experiments to grow out oospore-infested spinach seed and noninfested seeds mixed with oospore-infested crop debris. Downy mildew diseased spinach plants were observed 37 and 34 days after planting in the two isolator experiments, respectively, in the chambers that contained one of two oospore-infested seed lots or seeds coated with oospore-infested leaves. Spinach plants in isolated glass chambers initiated from seeds without oospores did not show downy mildew symptoms. Similar findings were obtained using the same seed lot samples in a third experiment conducted in a growth chamber. In direct grow out tests to examine oospore infection on seedlings performed in a containment greenhouse with oospore-infested seed of two different cultivars, characteristic Peronospora sporangiophores were observed growing from a seedling of each cultivar. The frequency of seedlings developing symptoms from 82 of these oospore-infested seed indicated that approximately 2.4% of seedlings from infested seed developed symptoms, and 0.55% of seedlings from total seeds assayed developed symptoms. The results provide evidence that oospores can serve as a source of inoculum for downy mildew and provide further evidence of direct seed transmission of the downy mildew pathogen to seedlings in spinach via seedborne oospores.

Characterization of Stemphylium species associated with Stemphylium leaf spot of spinach (Spinacia oleracea).

Stemphylium leaf spot can result in significant losses to spinach seed, processing, and fresh market crops. Stemphylium isolates (n = 1,775) collected from 2000 to 2022 from spinach seed, leaves, and seed crop stem residues were used to assess the diversity of species associated with spinach. Eleven Stemphylium species were identified based on cmdA sequences: S. vesicarium (63.6% of isolates), S. beticola (48.9%), S. amaranthi (5.1%), S. eturmiunum (4.5%), S. astragali (4.0%), S. simmonsii (3.4%), and S. lucomagnoense, S. drummondii, S. gracilariae, S. lycopersici, and S. chrysanthemicola (each 0.6 to 1.7%). Only isolates of S. beticola, S. drummondii, and S. vesicarium were pathogenic to spinach. The incidence of spinach seed on which Stemphylium was observed ranged from 2.5 to 73.5% per seed lot, with S. vesicarium and S. beticola predominant. However, only 60.7 and 62.3% of isolates tested for these two species were pathogenic to spinach, respectively. Therefore, the incidence of Stemphylium species on spinach seed may not reflect accurately the risk of a seed lot carrying pathogenic isolates. Fused MAT1-1 and MAT1-2 genes were detected in isolates of S. vesicarium, but only MAT1-1 was detected in S. beticola isolates, which corroborates previous studies that have proposed the two species to be self-fertile. The duration of ascospore dispersal of S. beticola and S. vesicarium from spinach seed crop stem residues in western Washington, the primary region of spinach seed production in the USA, occurred from mid-winter to late spring or early fall, potentially serving as inoculum for the next season's spinach seed crops. Growers should incorporate residues into the soil after harvest to reduce inoculum production of these pathogens on spinach seed crop residues.

Quinoa as phytopharmaceutical? Urinary elimination of ecdysterone after consumption of quinoa alone and in combination with spinach.

The phytosteroid ecdysterone is classified as an anabolic agent and has been included on the monitoring list of the World Anti-Doping Agency since 2020. Therefore, the consumption of food rich in ecdysterone, such as quinoa and spinach, is the focus of a lively debate. Thus, the urinary excretion of ecdysterone and its metabolites in humans was investigated following quinoa consumption alone and in combination with spinach. Eight participants (four male and four female) were included, and they ingested 368 ± 61 g cooked quinoa alone and in combination with 809 ± 115 g spinach after a washout. Post-administration urines were analyzed by LC-MS/MS. After intake of both preparations, ecdysterone and two metabolites were excreted in the urine. The maximum concentration of ecdysterone ranged from 0.44 to 5.5 µg/mL after quinoa and from 0.34 to 4.1 µg/mL after quinoa with spinach. The total urinary excreted amount as parent drug plus metabolites was 2.61 ± 1.1% following quinoa intake and 1.7 ± 0.9% in combination with spinach. Significant differences were found in the total urinary excreted amount of ecdysterone, 14-deoxy-ecdysterone, and 14-deoxy-poststerone. Only small portions of ecdysterone from quinoa and the combination with spinach were excreted in the urine, suggesting that both quinoa and spinach are poor sources of ecdysterone in terms of bioavailability.

Influence of brassinosteroid and silicon on growth, antioxidant enzymes, and metal uptake of leafy vegetables under wastewater irrigation.

Vegetable cultivation under sewage irrigation is a common practice mostly in developing countries due to a lack of freshwater. Long-term usage provokes heavy metals accumulation in soil and ultimately hinders the growth and physiology of crop plants and deteriorates the quality of food. A study was performed to investigate the role of brassinosteroid (BRs) and silicon (Si) on lettuce, spinach, and cabbage under lead (Pb) and cadmium (Cd) contaminated sewage water. The experiment comprises three treatments (control, BRs, and Si) applied under a completely randomized design (CRD) in a growth chamber. BRs and Si application resulted in the highest increase of growth, physiology, and antioxidant enzyme activities when applied under canal water followed by distilled water and sewage water. However, BRs and Si increased the above-determined attributes under the sewage water by reducing the Pb and Cd uptake as compared to the control. It's concluded that sewerage water adversely affected the growth and development of vegetables by increasing Pb and Cd, and foliar spray of Si and BRs could have great potential to mitigate the adverse effects of heavy metals and improve the growth. The long-term alleviating effect of BRs and Si will be evaluated in the field conditions at different ecological zones.

Exploring the Impact of Alternative Sources of Dietary Nitrate Supplementation on Exercise Performance.

An increase in the level of nitric oxide (NO) plays a key role in regulating the human cardiovascular system (lowering blood pressure, improving blood flow), glycemic control in type 2 diabetes, and may help enhance exercise capacity in healthy individuals (including athletes). This molecule is formed by endogenous enzymatic synthesis and the intake of inorganic nitrate (NO3-) from dietary sources. Although one of the most well-known natural sources of NO3- in the daily diet is beetroot (Beta vulgaris), this review also explores other plant sources of NO3- with comparable concentrations that could serve as ergogenic aids, supporting exercise performance or recovery in healthy individuals. The results of the analysis demonstrate that red spinach (Amaranthus spp.) and green spinach (Spinacia oleracea) are alternative natural sources rich in dietary NO3-. The outcomes of the collected studies showed that consumption of selected alternative sources of inorganic NO3- could support physical condition. Red spinach and green spinach have been shown to improve exercise performance or accelerate recovery after physical exertion in healthy subjects (including athletes).

Genome-Wide Identification and Characterization of MYB Gene Family and Analysis of Its Sex-Biased Expression Pattern in Spinacia oleracea L.

The members of the myeloblastosis (MYB) family of transcription factors (TFs) participate in a variety of biological regulatory processes in plants, such as circadian rhythm, metabolism, and flower development. However, the characterization of MYB genes across the genomes of spinach Spinacia oleracea L. has not been reported. Here, we identified 140 MYB genes in spinach and described their characteristics using bioinformatics approaches. Among the MYB genes, 54 were 1R-MYB, 80 were 2R-MYB, 5 were 3R-MYB, and 1 was 4R-MYB. Almost all MYB genes were located in the 0-30 Mb region of autosomes; however, the 20 MYB genes were enriched at both ends of the sex chromosome (chromosome 4). Based on phylogeny, conserved motifs, and the structure of genes, 2R-MYB exhibited higher conservation relative to 1R-MYB genes. Tandem duplication and collinearity of spinach MYB genes drive their evolution, enabling the functional diversification of spinach genes. Subcellular localization prediction indicated that spinach MYB genes were mainly located in the nucleus. Cis-acting element analysis confirmed that MYB genes were involved in various processes of spinach growth and development, such as circadian rhythm, cell differentiation, and reproduction through hormone synthesis. Furthermore, through the transcriptome data analysis of male and female flower organs at five different periods, ten candidate genes showed biased expression in spinach males, suggesting that these genes might be related to the development of spinach anthers. Collectively, this study provides useful information for further investigating the function of MYB TFs and novel insights into the regulation of sex determination in spinach.

Evolution and Dynamic Transcriptome of Key Genes of Photoperiodic Flowering Pathway in Water Spinach (Ipomoea aquatica).

The photoperiod is a major environmental factor in flowering control. Water spinach flowering under the inductive short-day condition decreases the yield of vegetative tissues and the eating quality. To obtain an insight into the molecular mechanism of the photoperiod-dependent regulation of the flowering time in water spinach, we performed transcriptome sequencing on water spinach under long- and short-day conditions with eight time points. Our results indicated that there were 6615 circadian-rhythm-related genes under the long-day condition and 8691 under the short-day condition. The three key circadian-rhythm genes, IaCCA1, IaLHY, and IaTOC1, still maintained single copies and similar IaCCA1, IaLHY, and IaTOC1 feedback expression patterns, indicating the conservation of reverse feedback. In the photoperiod pathway, highly conserved GI genes were amplified into two copies (IaGI1 and IaGI2) in water spinach. The significant difference in the expression of the two genes indicates functional diversity. Although the photoperiod core gene FT was duplicated to three copies in water spinach, only IaFT1 was highly expressed and strongly responsive to the photoperiod and circadian rhythms, and the almost complete inhibition of IaFT1 in water spinach may be the reason why water spinach does not bloom, no matter how long it lasts under the long-day condition. Differing from other species (I. nil, I. triloba, I. trifida) of the Ipomoea genus that have three CO members, water spinach lacks one of them, and the other two CO genes (IaCO1 and IaCO2) encode only one CCT domain. In addition, through weighted correlation network analysis (WGCNA), some transcription factors closely related to the photoperiod pathway were obtained. This work provides valuable data for further in-depth analyses of the molecular regulation of the flowering time in water spinach and the Ipomoea genus.