Magnesium nanoparticles extirpate salt stress in carrots (Daucus carota L.) through metabolomics regulations

Underground vegetables are sensitive and vulnerable to salt stress. The vegetables are the main source of vitamins, nutrients and minerals in human diet. Also contain healthy carbohydrates, antioxidant and resistant starch which are beneficial for human health. Salinity influences water balance, morphological appearance and cellular interference of crop plants. It also caused disproportion of nutrients which usually affects the physiochemical processes in plant. Salt stress also affect biochemical attributes and hampers the growth of underground organs, due to which yield of crop decreased. The nanoparticles had been potentially used for better crop yield, in the recent. In our research study, we elaborate the positive response of magnesium oxide nanoparticles (MgO-NPs) on the morphological and biochemical parameters as well as anti-oxidant enzymes action on two accessions of carrot (Daucus carota L.) under salt stress of 40 mM and 80 mM. In a pilot experiment, various levels (0, 50, 100, 150, 200 and 250 mg/L) of MgO-NPs were tested through foliar application on carrot plants. Foliar application of MgO-NPs at concentration of 150 mg/L was most effective treatment and ameliorate the salt stress in both carrot accessions (DC-03 and DC-90). The MgO-NPs significantly enhanced the morphological and biochemical parameters. The yield was significantly increased with the exposure of MgO-NPs. Our results thus confirmed the potential of MgO-NPs to endorse the plant development and growth under salinity. However, further research study is needed to explore effectiveness of MgO-NPs in various other plants for the ameliorant of salinity.

TPP-chitosomes as potential encapsulation system to protect carotenoid-rich extract obtained from carrot by-product: A comparison with liposomes and chitosomes

The objectives of this study were to extract bioactive compounds from carrot by-products and evaluate their chemical stability after encapsulation in liposomes (L) coated either with chitosan (Ch) or using sodium tripolyphosphate for chitosan complexation (TPP-Ch). The main compounds quantified in this study were carotenoids and total phenolic compounds, which reached encapsulation efficiencies higher than 75%. The TPP-Ch charged with carrot extract showed greater particle size (90.5 nm) and zeta potential (+22 mV) than vesicles without coating (68.0 nm and -2 mV, respectively), indicating that liposomes were successfully coated with chitosan. Regarding results of the carotenoid's encapsulated stability, TPP-Ch particles were more efficient preventing their degradation in all the experimental conditions studied (40 and 70 °C). It is significant that loaded TPP-Ch particles demonstrated similar results for the stability of carotenoid-rich extracts in ethanol, which would therefore be suitable for application in food industry or any aqueous matrices.

Impact of Cultivar Selection and Thermal Processing by Air Drying, Air Frying, and Deep Frying on the Carotenoid Content and Stability and Antioxidant Capacity in Carrots (Daucus carota L.)

Epidemiological data suggest that consuming diets rich in carotenoids can reduce the risk of developing several non-communicable diseases. Thus, we investigated the extent to which carotenoid contents of foods can be increased by the choice of food matrices with naturally high carotenoid contents and thermal processing methods that maintain their stability. For this purpose, carotenoids of 15 carrot (Daucus carota L.) cultivars of different colors were assessed with UHPLC-DAD-ToF-MS. Additionally, the processing effects of air drying, air frying, and deep frying on carotenoid stability were applied. Cultivar selection accounted for up to 12.9-fold differences in total carotenoid content in differently colored carrots and a 2.2-fold difference between orange carrot cultivars. Air frying for 18 and 25 min and deep frying for 10 min led to a significant decrease in total carotenoid contents. TEAC assay of lipophilic extracts showed a correlation between carotenoid content and antioxidant capacity in untreated carrots.

Characteristics of the AT-Hook Motif Containing Nuclear Localized (AHL) Genes in Carrot Provides Insight into Their Role in Plant Growth and Storage Root Development

The AT-hook motif containing nuclear localized (AHL) gene family, controlling various developmental processes, is conserved in land plants. They comprise Plant and Prokaryote Conserved (PPC) domain and one or two AT-hook motifs. DcAHLc1 has been proposed as a candidate gene governing the formation of the carrot storage root. We identified and in-silico characterized carrot AHL proteins, performed phylogenetic analyses, investigated their expression profiles and constructed gene coexpression networks. We found 47 AHL genes in carrot and grouped them into two clades, A and B, comprising 29 and 18 genes, respectively. Within Clade-A, we distinguished three subclades, one of them grouping noncanonical AHLs differing in their structure (two PPC domains) and/or cellular localization (not nucleus). Coexpression network analysis attributed AHLs expressed in carrot roots into four of the 72 clusters, some of them showing a large number of interactions. Determination of expression profiles of AHL genes in various tissues and samples provided basis to hypothesize on their possible roles in the development of the carrot storage root. We identified a group of rapidly evolving noncanonical AHLs, possibly differing functionally from typical AHLs, as suggested by their expression profiles and their predicted cellular localization. We pointed at several AHLs likely involved in the development of the carrot storage root.

Cytokinin (6-benzylaminopurine) elevates lignification and the expression of genes involved in lignin biosynthesis of carrot

Carrot is a root crop consumed worldwide and has great nutritional qualities. It is considered as one of the ten most important vegetable crops. Cytokinins are an essential class of the plant hormones that regulate many processes of plant growth. Till now, the effects of cytokinin, BAP, on lignin biosynthesis and related gene expression profiles in carrot taproot is unclear. In order to investigate the effect of applied BAP on lignin-related gene expression profiles, lignin accumulation, anatomical structures, and morphological characters in carrot taproots. Carrot roots were treated with different concentrations of BAP (0, 10, 20, and 30 mg L^-1). The results showed that the application of BAP significantly increased plant length, shoot fresh weight, root fresh weight, and taproot diameter. In addition, BAP at 20 mg L^-1 or 30 mg L^-1 enhanced the average number of petioles. BAP treatment led to increased number and width of xylem vessels. The parenchyma cell numbers of pith were significantly induced in taproots treated with the BAP at a concentration of 30 mg L^-1. BAP significantly upregulated most of the expression levels of lignin biosynthesis genes, caused elevated lignin accumulation in carrot taproots. Our results indicate that BAP may play important roles in growth development and lignification in carrot taproots. Our results provide a valuable database for more studies, which may focus on the regulation of root lignification via controlling cytokinin levels in carrot taproots.

Effect of cetyltrimethyl ammonium bromide on uptake of polycyclic aromatic hydrocarbons by carrots

This is the first study investigating the effect of cationic surfactants on the mobility of polycyclic aromatic hydrocarbons (PAHs) in aged contaminated soils and on PAH bioaccumulation in tuberous vegetables. In an aerobic soil incubation experiment, 150 mg/kg cetyltrimethyl ammonium bromide (CTMAB) decreased the bioavailability of PAHs primarily via immobilization (by 13%). In a carrot pot experiment, the effectiveness of CTMAB to reduce PAH uptake by carrots decreased with time. Accordingly, the bioavailability of PAHs in the soil decreased in the first 90 days and then increased and remained stable until harvest. In the leaching test, the leaching loss of CTMAB (15%) was lower in soils treated with small amounts of CTMAB in several applications than it was in soils (24%) treated once with CTMAB. Therefore, CTMAB, when applied in appropriate doses via addition methods, can effectively reduce the environmental risk of PAH entering humans and livestock through the food chain.

Transcript profiling of sucrose synthase genes involved in sucrose metabolism among four carrot (Daucus carota L.) cultivars reveals distinct patterns

BACKGROUND

Carrot which contains lots of nutrients has a large demand around the world. The soluble sugar content in fleshy root of carrot directly influences its taste and quality. Sucrose, as an important member of soluble sugar, is the main product of photosynthesis in higher plants and it plays pivotal roles in physiological processes including energy supply, signal transduction, transcriptional regulation, starch and cellulose synthesis, and stress tolerance. Sucrose synthase is a key enzyme involved in sucrose metabolism and is closely related to sucrose content. However, the molecular mechanism involved in sucrose metabolism in carrot has lagged behind.

RESULTS

Here, carrot roots of five developmental stages from four carrot cultivars were collected, and the contents of soluble sugar and sucrose in different stages and cultivars were surveyed. Three DcSus genes (DcSus1, DcSus2, and DcSus3), with lengths of 2427 bp, 2454 bp and 2628 bp, respectively, were identified and cloned in carrot. Phylogenetic analysis from the deduced amino acid sequences suggested that three DcSus were clustered into three distinct groups (SUSI, II and III). Results of enzymatic profiles demonstrated that the DcSus activities showed decrease trends during taproot development. Correlation analysis indicated that the DcSus activity showed negative correlation with soluble sugar content and strong negative correlation with sucrose concentration. Quantitative real-time PCR analysis showed that the expression profiles of the DcSus genes are significantly different in carrot tissues (root, leaf blade, and petiole), and the expression levels of the DcSus genes in the leaf blade were much higher than that in the root and petiole. The expression profiles of DcSus genes showed strong negative correlation with both sucrose content and soluble sugar content.

CONCLUSIONS

During carrot root development, the soluble sugar content and sucrose content showed increasing trends, while DcSus activities had persisting declinations, which may be due to the decreasing expression levels of genes encoding sucrose synthase. Our data demonstrate that synthesis of sucrose in carrot tissue is closely related with DcSus genes. The results from our study would not only provide effective insights of sucrose metabolism in carrot, but also are beneficial for biologists to improve carrot quality.

Exogenous gibberellin enhances secondary xylem development and lignification in carrot taproot

Gibberellins (GAs) are important growth regulators involved in plant development processes. However, limited information is known about the relationship between GA and xylogenesis in carrots. In this study, carrot roots were treated with GA₃. The effects of applied GA₃ on root growth, xylem development, and lignin accumulation were then investigated. Results indicated that GA treatment dose-dependently inhibited carrot root growth. The cell wall significantly thickened in the xylem parenchyma. Autofluorescence analysis with ultraviolet (UV) excitation indicated that these cells became lignified because of long-term GA₃ treatment. Moreover, lignin content increased in the roots, and the transcripts of lignin biosynthesis genes were altered in response to applied GA₃. Our data indicate that GA may play important roles in xylem growth and lignification in carrot roots. Further studies shall focus on regulating plant lignification, which may be achieved by modifying GA levels within plant tissues.

Respiration Traits as Novel Markers for Plant Robustness Under the Threat of Climate Change: A Protocol for Validation

Respiration traits allow calculating temperature-dependent carbon use efficiency and prediction of growth rates. This protocol aims (1) to enable validation of respiration traits as non-DNA biomarkers for breeding on robust plants in support of sustainable and healthy plant production; (2) to provide an efficient, novel way to identify and predict functionality of DNA-based markers (genes, polymorphisms, edited genes, transgenes, genomes, and hologenomes), and (3) to directly help farmers select robust material appropriate for a specified region. The protocol is based on applying isothermal calorespirometry and consists of four steps: plant tissue preparation, calorespirometry measurements, data processing, and final validation through massive field-based data.The methodology can serve selection and improvement for a wide range of crops. Several of them are currently being tested in the author's lab. Among them are important cereals, such as wheat, barley, and rye, and diverse vegetables. However, it is critical that the protocol for measuring respiration traits be well adjusted to the plant species by considering deep knowledge on the specific physiology and functional cell biology behind the final target trait for production. Here, Daucus carota L. is chosen as an advanced example to demonstrate critical species-specific steps for protocol development. Carrot is an important global vegetable that is grown worldwide and in all climate regions (moderate, subtropical, and tropical). Recently, this species is also used in my lab as a model for studies on alternative oxidase (AOX) gene diversity and evolutionary dynamics in interaction with endophytes.

Residual tembotrione and atrazine in carrot

Carrot (Daucus carota L.) is a vegetable crop that is grown throughout the year across various regions of Brazil in rotation or in succession to other cultures. Herbicide residual effect has emerged as a concern, because of the possibility of carryover. Thus, the objective of this study was to evaluate the effect of tembotrione and atrazine residues - in mixture and isolated - on carrot planted in succession to corn. The experiment was designed in randomized blocks with five replications. Treatments consisted of tembotrione (50.4 g ha(-1)), tembotrione (100.8 g ha(-1)), tembotrione + atrazine (50.4 g ha(-1)+ 2 L ha(-1)), tembotrione + atrazine (100.8 g ha(-1)+ 2 L ha(-1)), and atrazine (2.00 L ha(-1)) applied eight months before carrot seeding, plus a control treatment with no herbicide application. Investigated variables were shoot dry mass, productivity, and classification of carrot roots. The presence of atrazine and tembotrione decreased dry mass in the area, and only tembotrione reduced total root productivity. Thus, there is a carryover effect to tembotrione application that reduces the dry matter accumulation of shoot and total productivity, and an atrazine + tembotrione (100.8 g ha(-1)) mixture reduces the total productivity after application of these herbicides to soil.

Regulation of ascorbic acid biosynthesis and recycling during root development in carrot (Daucus carota L.)

Ascorbic acid (AsA), also known as vitamin C, is an essential nutrient in fruits and vegetables. The fleshy root of carrot (Daucus carota L.) is a good source of AsA for humans. However, the metabolic pathways and molecular mechanisms involved in the control of AsA content during root development in carrot have not been elucidated. To gain insights into the regulation of AsA accumulation and to identify the key genes involved in the AsA metabolism, we cloned and analyzed the expression of 21 related genes during carrot root development. The results indicate that AsA accumulation in the carrot root is regulated by intricate pathways, of which the l-galactose pathway may be the major pathway for AsA biosynthesis. Transcript levels of the genes encoding l-galactose-1-phosphate phosphatase and l-galactono-1,4-lactone dehydrogenase were strongly correlated with AsA levels during root development. Data from this research may be used to assist breeding for improved nutrition, quality, and stress tolerance in carrots.

Two new eudesmane-type glucopyranosides from the fruits of Daucus carota L

Two new eudesmane-type glucopyranosides have been isolated from the fruits of Daucus carota L. On the basis of their spectroscopic and chemical evidence, the new compounds were elucidated as daucucarotol-10-O-β-D-glucopyranoside (1) and decahydro-7-[(2-O-β-D-glucopyranosyl)-isopropyl]-1β,4aα-dimethyl-(1α,4α,8aβ)-naphthalenetriol (2). Compounds 1 and 2 showed moderate antitumour activity against human ECA-109 and gave IC50 values of 23.22 and 26.76 μM, respectively.