Carrot Tissue Research Articles

Anthocyanin glucosylation mediated by a glycoside hydrolase family 3 protein in purple carrot.

Purple carrot accumulates anthocyanins modified with galactose, xylose, glucose, and sinapic acid. Most of the genes associated with anthocyanin biosynthesis have been identified, except for the glucosyltransferase genes involved in the step before the acylation in purple carrot. Anthocyanins are commonly glycosylated in reactions catalyzed by UDP-sugar-dependent glycosyltransferases (UGTs). Although many studies have been conducted on UGTs, the glucosylation of carrot anthocyanins remains unknown. Acyl-glucose-dependent glucosyltransferase activity modifying cyanidin 3-xylosylgalactoside was detected in the crude protein extract prepared from purple carrot cultured cells. In addition, the corresponding enzyme was purified. The cDNA encoding this glucosyltransferase was isolated based on the partial amino acid sequence of the purified protein. The recombinant protein produced in Nicotiana benthamiana leaves via agroinfiltration exhibited anthocyanin glucosyltransferase activity. This glucosyltransferase belongs to the glycoside hydrolase family 3 (GH3). The expression pattern of the gene encoding this GH3-type anthocyanin glucosyltransferase was consistent with anthocyanin accumulation in carrot tissues and cultured cells.

A Study on the Effect Mechanism of Pectin Modification on the Carrot Cell Wall’s Texture Formation under Ultrasonic and Infrared Drying

The carrot has a high water content, and dehydration is an important means to extend its edible period and reduce storage and transportation costs. In the case of infrared (IR) drying, the porosity of the product is low and the structure is compact; the textural properties of the product are improved by using combined ultrasound and infrared (US-IR) drying; however, there is a lack of reports on the mechanism of this. Pectin has an important influence on the formation of the textural properties of fruit and vegetable tissues. In order to investigate the mechanism of the change in endogenous pectin properties in the carrot cell wall under US-IR drying on the improvement of the textural properties of the product, different fractions of pectins (water-soluble pectin, chelating pectin, alkali-soluble pectin) of the carrot were extracted, separated, and analysed. The thermal stability, component and content changes, Fourier infrared (FTIR), X-ray diffraction (XRD), esterification degree, molecular weight, monosaccharide composition, Ca ion content, and atomic force microscopy (AFM) of the pectins were determined. The results showed that the changes in the contents and properties of the carrot pectins under US-IR conditions had a positive effect on the improvement of the textural properties of the carrot tissues.

Changes in the prevalence of fungal species causing post‐harvest diseases of carrot in Finland

AbstractPost‐harvest diseases cause significant economic losses in the carrot production chain. In this study, storage losses and fungal pathogens causing them were analysed in the carrot yield from 52 different field plots in four areas in Finland in 3 years (2016–2018). Over 30,000 carrots were sampled and analysed at three time points during cold storage at 0–1°C. In March, after 5–6 months' storage, the average loss due to diseases was 20%–21% every year. Decay of the root tip was the most common disease symptom, followed by pits on the side and black rot in the crown, detected in 69.2%, 15.0% and 9.0% of the symptomatic samples, respectively. Both intensive carrot cultivation practice and early timing of harvest increased storage losses. Pathogens in 3057 symptomatic carrot tissue samples were isolated by culturing, and fungal species were identified. The most common fungal species detected were Mycocentrospora acerina, Botrytis cinerea and Fusarium spp., especially F. avenaceum. However, the frequency of different pathogens varied between the different years and time points during storage. Species‐specific PCR tests revealed that M. acerina and F. avenaceum were present in many early time‐point samples where they could not yet be detected by the culturing method. In Finland, this study on carrot post‐harvest diseases is the first large‐scale survey in which the fungal pathogens were isolated and identified by laboratory tests. In comparison with the previous studies, Fusarium spp. were detected more frequently in this study, while grey mould and Sclerotinia rot were less frequent.

Invertase Plays a Vital Role in Regulating Wound-Induced Accumulation of Phenolic Compounds in Carrot Tissue

The application of wounding stress can induce the accumulation of phenolic antioxidants in carrots. This study aimed to investigate the possible regulation role of invertase (INV) on the biosynthesis of phenolics in wounded carrots. In this study, carrots were cut into two different wounding intensities of slices and cubes, then stored at 20 °C for 2 days. The results showed that wounding stress caused an obvious increase in phenolic content and antioxidant capacity in carrot tissues, and a positive correlation was observed between the biosynthesis of phenolic compounds and the degradation of sucrose. Simultaneously, wounding activated the sucrose-cleaving enzymes of INVs, including acid INV (AI) and neutral INV (NI), and up-regulated the expressions of most encoding genes of INVs. In addition, treatment with INV activators accelerated the accumulation of phenolic antioxidants, while treatment with INV inhibitors suppressed this process, suggesting that the synthesis of phenolic compounds in wounded carrots is closely related to the availability of sugars. Our findings provide new insights into the regulation role of INV on the wound-induced accumulation of phenolic compounds in carrots, which may be helpful in using wounded plants to produce more phenolic antioxidants.

Field surveys indicate taxonomically diverse Pectobacterium species inducing soft rot of vegetables and annual crops in Iran

AbstractSoft rot‐inducing bacterial pathogens are considered among the main biotic constraints on vegetables and annual crops. Most of the bacterial soft rot pathogens are members of Pectobacterium spp. and Dickeya, with the former genus encompassing a continuously increasing number of species varying in geographic distribution and host of isolation. In Iran, Pectobacterium species have rarely been investigated using high‐throughput nucleotide sequence‐based techniques, leaving the genetic diversity of these pathogens mostly undetermined. During 2021, vegetables and annual crops with symptoms of soft rot and maceration were collected from Fars, Hamedan, Isfahan, Khuzestan and Kohgiluyeh‐Boyer‐Ahmad provinces of Iran. Forty‐four pectinolytic bacterial strains were isolated from symptomatic tissues of bell pepper, cabbage, carrot, lettuce, potato and zucchini. The bacterial strains were subjected to pathogenicity and host range assays, specific PCR tests and phylogenetic analysis of three housekeeping genes (dnaX, gapA and leuS). All strains were pathogenic on their host of isolation. Among the 44 pectinolytic strains, 26 strains were identified as members of Pectobacterium based on PCR using the primer pair Y1/Y2. Multilocus sequence analysis confirmed the latter bacterial strains belonging to the genus Pectobacterium and revealed that the strains scattered into four species: P. brasiliense (five strains), P. carotovorum (eight strains), P. polaris (five strains) and P. versatile (eight strains). P. polaris and P. versatile have not previously been reported in the country. Host range assays showed that P. brasiliense and P. carotovorum have a broader host range than the other two species.

Residue and Risk Assessment of Fluopyram in Carrot Tissues.

This study describes the variation in residue behavior of fluopyram in soil, carrot root, and carrot leaf samples after the application of fluopyram (41.7% suspension, Bayer) by foliar spray or root irrigation at the standard of 250.00 g active ingredient per hectare (a.i./ha) and double-dose treatment (500.00 g a.i./ha). Fluopyram and its metabolite fluopyram-benzamide were extracted and cleaned up using the QuEChERS method and subsequently quantified with LC-QQQ-MS/MS. The LOD and LOQ of the developed method were in the range of 0.05–2.65 ug/kg and 0.16–8.82 ug/kg, respectively. After root irrigation, the final residues detected in edible parts were 0.60 and 1.80 mg/kg, respectively, when 250.00 and 500.00 g a.i./ha were applied, which is much higher than the maximum residue limit in China (0.40 mg/kg). In contrast, after spray application, most of the fluopyram dissipated from the surface of carrot leaves, and the final residues in carrot roots were both only 0.05 mg/kg. Dietary risk assessments revealed a 23–40% risk quotient for the root irrigation method, which was higher than that for the foliar spray method (8–14%). This is the first report comparing the residue behavior of fluopyram applied by root irrigation and foliar spray. This study demonstrates the difference in risk associated with the two application methods and can serve as a reference for the safe application of fluopyram.

Effect of thermosonication on texture degradation of carrot tissue in relation to alterations in cell membrane and cell wall structure

Thermosonication as an alternative to hot water blanching of carrots, the effect of thermosonication on the carrot texture and cell structure required deep investigation. This study was conducted from the aspects of cell membrane, cell water, and cell wall pectin. Results showed that thermosonication at 60 °C significantly increased carrot tissue hardness by up to 10.3% compared with fresh. Rheological curves showed that the carrot tissues remained rigid after thermosonication. Cell membrane permeability was damaged to different extents during processing, inducing bound and immobilized water to migrate to free water and bring intracellular electrolytes to outflow. Thermosonication affected cell structure by altering the characteristics of pectin, including uronic acids and neutral sugar contents, degree of linearity and branching, and degree of methoxylation. The modified pectin can seize more divalent cations such as Ca2+ retained in the thermosonicated carrot cell wall, conducive to preserving the textural property of processed fruits and vegetables.

Correlation of the cell disintegration index with Luikov's heat and mass transfer parameters for drying of pulsed electric field (PEF) pretreated plant materials

Currently, the modelling of drying processes of plant tissues pre-treated by pulsed electric field (PEF) is following experimentally identified curves or separate heat and mass transfer and diffusion models with different levels of accuracy. This research had two major objectives: mathematical modeling and control of drying process of different vegetables pretreated by PEF during convective drying. The mathematical modeling was based on Luikov's heat and mass transfer model along with properties of different vegetables. Computer modelling was done using the difference method for predicting moisture and the temperature potentials of untreated and PEF-treated vegetables. The formulation and the solution procedures were applied to simulate the simultaneous heat and mass transfer in selected vegetables subjected to the convective drying. Suggested model had a good correlation with experimental results. Moreover, cell disintegration index can be used as a controllable parameter in heat and mass transfer models to predict drying behavior of potato, onion, and carrot tissues. Obtained drying models can be used as a mathematical tool to predict drying behavior for various types of agricultural products pre-treated by pulsed electric field. • Pulsed electric field (PEF) pre-treatment reduced the drying time. • Obtained methodology is a good tool for the analysis and modelling of PEF assisted drying. • Cell disintegration index is in relationship with the kinetics coefficients of Luikov's model. • Cell disintegration index can be used to predict drying behavior of plant tissues.

Bioaccumulation of Manure-borne antibiotic resistance genes in carrot and its exposure assessment.

The effect of manure application on the distribution and accumulation of antibiotic resistance genes (ARGs) in tissue of root vegetables remains unclear, which poses a bottleneck in assessing the health risks from root vegetables due to application of manure. Towards this goal, experiments were conducted in pots to investigate the distribution and bioaccumulation of ARGs in carrot tissues due to application of pig manure. The 144 ARGs targeting nine types of antibiotics were quantified by high throughput qPCR in the soil and plant samples. The rhizosphere was a hot spot for ARGs enrichment in the manured soil. The abundance, diversity, and bioaccumulation factors of ARGs in the phyllosphere were significantly higher than those of carrot root skin and tuber. Manure application increased bioaccumulation of 12 ARGs and 2 MGEs in carrot tuber with 124 the highest factor. The application of manure increased transfer of 10 ARGs and 3 MGEs from carrot skin to inner tuber by factors of 0.1-11.8. The average gene copy number of ARGs of per gram carrot root was about 4.8×104 and 1.1×106 in the control and the manured treatment, respectively. Children and adults may co-ingest 2.7×107 and 3.2×107 of ARGs copies/d from carrots grown with pig manure, using estimated human intake values. However, peeling may reduce the intake of ARGs by 28-91% and of MGEs by 46-59%. In conclusion, the application of pig manure increased the accumulation of ARGs in the skin of carrots, whereas peeling was an effective strategy to reduce the risk.

Development of STEM tissue culture module in promoting plant biotechnology

Tissue culture is a part of modern biotechnology, which offers a lot of potential in tackling food security, genetic conservation and plant breeding. Thus, it is important to introduce plant biotechnology to the young generation in order to foster their positive attitude, which ultimately in the future, will result in human capital and public awareness in the field itself. This study focused on the development of STEM tissue culture module as a teaching aids to introduce plant biotechnology and exposing the variety of STEM career at school level among primary school students of ages 10-12 years old. This module consists of four activities focusing on the seed identification, water transportation in plants, grass doll and carrot tissue culture. Based on the conducted survey, 80% of the participants exhibited interest in the tissue culture module with 42% reacted positively on the statement that this module triggered their curiosity on plant biotechnology. Hence, this module is a promising teaching aid to promote STEM especially in plant biotechnology.

Effect of pulsed electric field and mild thermal processing on texture-related pectin properties to better understand carrot (Daucus carota) texture changes during subsequent cooking

Pulsed electric field (PEF) and/or mild thermal (60 °C) processing distinctly affect the texture degradation of carrot tissues during subsequent cooking. The impact of PEF and/or mild thermal processing on texture-related pectin properties was studied in terms of pectin extractability, degree of methylesterification (DM) and Ca2+ crosslinking in carrot cortex and vascular tissue. In the case of cortex tissue, the treatments significantly (α = 0.05) reduced the extractability of pectin in water and alkali; the pectin DM and ionic crosslinking were not affected. In the case of vascular tissue, mainly the PEF and combination treatment reduced the extractability of pectin in water and alkali, reduced the pectin DM (approx. 60 to 50%), and improved its ionic crosslinking. Addition of Ca2+ ions may help preserve the texture of both tissues during subsequent cooking. Further research is necessary to investigate the effect of the treatments on covalent pectin crosslinking, especially in cortex tissue.

Insights into long non-coding RNA regulation of anthocyanin carrot root pigmentation

Carrot (Daucus carota L.) is one of the most cultivated vegetable in the world and of great importance in the human diet. Its storage organs can accumulate large quantities of anthocyanins, metabolites that confer the purple pigmentation to carrot tissues and whose biosynthesis is well characterized. Long non-coding RNAs (lncRNAs) play critical roles in regulating gene expression of various biological processes in plants. In this study, we used a high throughput stranded RNA-seq to identify and analyze the expression profiles of lncRNAs in phloem and xylem root samples using two genotypes with a strong difference in anthocyanin production. We discovered and annotated 8484 new genes, including 2095 new protein-coding and 6373 non-coding transcripts. Moreover, we identified 639 differentially expressed lncRNAs between the phenotypically contrasted genotypes, including certain only detected in a particular tissue. We then established correlations between lncRNAs and anthocyanin biosynthesis genes in order to identify a molecular framework for the differential expression of the pathway between genotypes. A specific natural antisense transcript linked to the DcMYB7 key anthocyanin biosynthetic transcription factor suggested how the regulation of this pathway may have evolved between genotypes.

The Assessment of the Possibility of Using Ethanol and Ultrasound to Design the Properties of Dried Carrot Tissue

The purpose of this study was to investigate the effect of pre-treatment in ethyl alcohol for 5, 15, 60 and 180 s with the application of ultrasound on the course of convective drying and properties of carrot tissue directly after the treatment and after the drying process. The treatment in ethanol resulted in loss of mass, increase of dry matter, ethanol conductivity, extractivity of carotenoids with a slight effect on the colour of carrot tissue after the treatment. The utilization of ultrasound during immersion in ethanol contributed to additional increase of conductivity of ethanol, and extractivity of carotenoids. The immersion in ethanol virtually did not affect the drying kinetics, which can be explained by the increase of shrinkage of the tissue in relation to the untreated dried tissue. Despite the lack of the influence on the drying course in the ethanol-immersed carrot, an increase of the carotenoid content (up to 135%) and the rehydration ability (up to 19%) was noted with the simultaneously unchanged colour of dried carrot in comparison to untreated dried material, which indicates the possibility to improve the quality of dried carrot after immersion in ethanol.

Uptake of microplastics by carrots in presence of As (III): Combined toxic effects

Current research on the migration of microplastics into plants is in its most important phase; however, there is no such research on root vegetables, even though the edible parts of root vegetables are in direct contact with microplastics. Considering arsenic (As)-containing groundwater used in hydroponics and the degradation of plastic materials in hydroponic facilities, we investigated the impacts of As and polystyrene (PS) microplastics on carrot growth. We found that PS microplastics sized 1 µm can enter carrot roots and accumulate in the intercellular layer but are unable to enter the cells; those sized 0.2 µm can migrate to the leaves. Larger microplastics can enter the roots (PS particles sized 1219.7 nm) and leaves (607.2 nm) in presence of As (III). Gaussian analysis shows that As increases the negatively charged area of PS and causes a greater amount of microplastics to enter the carrot. As also causes cell walls to distort and deform, allowing PS particles (< 200 nm) to enter the cells. PS and 4 mg L−1 As can induce oxidative bursts in carrot tissue, reducing the carrot quality. Moreover, As exacerbates the effect of PS on carrots. Molecular docking results show that the presence of PS in carrots destroys the tertiary structure of pectin methyl esterase and causes carrots to lose their crispness. These findings indicate that plastic material in hydroponic facilities can be leached to crops. Microplastics produced by the degradation of such materials not only reduce the nutritional value of carrots, leading to economic losses, but also pose potential risks to human health. The presence of As in the hydroponic solution results in more PS entering the carrot tissue and even the cells, bringing greater health threats for the consumers.

Physiological role of reactive oxygen species, ethylene, and jasmonic acid on UV light induced phenolic biosynthesis in wounded carrot tissue

Abstract Phenolic biosynthesis in carrots is increased when subjected to wounding and ultraviolet (UV) light stresses. In this study, the physiological role of reactive oxygen species (ROS), ethylene (ET), and jasmonic acid (JA) as signaling molecules to elicit this stress response was evaluated. ROS (O2− and hydrogen peroxide) were the first signaling molecules produced, then ET, followed by lipoxygenase (LOX) activity, which is a key enzyme in JA biosynthesis. After a sequence of syntheses of these signaling molecules, phenylalanine ammonia-lyase (PAL) was activated and phenolics were accumulated. We followed a chemical biology approach (using chemical inhibitors of stress-signaling pathways) to determine the physiological role of ROS, ET, and JA on the wound and UV (UVA, UVB, and UVC) induced biosynthesis of phenolics. Results indicated that ROS play a major role on the combined UV and wounding stress response. It is proposed that UV induces ROS which acts as a signal for ET biosynthesis, which in turn activates JA biosynthesis following the wound signaling cross-talk model we previously proposed. When both stresses are applied simultaneously, an enhanced effect on the accumulation of phenolics is observed due to higher levels of signaling molecules.

Impact of pulsed electric fields on vacuum drying kinetics and physicochemical properties of carrot

The effect of pulsed electric fields (PEF) on the kinetics of vacuum drying (VD) and rehydration of carrot tissue was studied. The intensity of PEF treatment was E = 0.6 kV/cm and the total PEF treatment duration was tPEF = 0.1 s. The VD was performed at sub-atmospheric pressure p = 3.03 × 104 Pa for different temperatures Td = 25 °C and 90 °C. During VD, the kinetics of moisture removal and temperature evolution inside of untreated and PEF pretreated samples were studied. The color and structure of the samples were also investigated. PEF pretreatment enhanced VD kinetics at different studied temperatures. However, its effect on VD was more evident at lower drying temperatures. With the PEF pretreatment, the drying time was reduced by 55% and 33% at 25 °C and 90 °C respectively. After the drying and rehydration process, the change in color of PEF pretreated samples was less significant compared to untreated ones. After rehydration, the untreated and PEF pretreated samples were nearly restored to their initial form and size.

Pulsed electric field and mild thermal processing affect the cooking behaviour of carrot tissues (Daucus carota) and the degree of methylesterification of carrot pectin

For the first time, the effect of pulsed electric field (PEF) and mild thermal processing on the texture of cortex and vascular carrot tissue during subsequent thermal processing (i.e. cooking behaviour) was compared and the degree of methylesterification (DM) of pectin from the pretreated tissues was investigated. The PEF and mild thermal pretreatment slowed down the cooking behaviour of the carrot tissues, especially when the pretreatments were combined. The DM of pectin from vascular tissue was lowered after both types of pretreatments, the effect being most pronounced in the case of the combination of the PEF and mild thermal pretreatment. In contrast, the DM of cortex pectin only decreased after the mild thermal pretreatment and after the combination pretreatment. This study demonstrates that besides mild thermal pretreatments also PEF pretreatments can be considered in the context of texture preservation of thermally processed fruits and vegetables.

Carrot Anthocyanins Genetics and Genomics: Status and Perspectives to Improve Its Application for the Food Colorant Industry.

Purple or black carrots (Daucus carota ssp. sativus var. atrorubens Alef) are characterized by their dark purple- to black-colored roots, owing their appearance to high anthocyanin concentrations. In recent years, there has been increasing interest in the use of black carrot anthocyanins as natural food dyes. Black carrot roots contain large quantities of mono-acylated anthocyanins, which impart a measure of heat-, light- and pH-stability, enhancing the color-stability of food products over their shelf-life. The genetic pathway controlling anthocyanin biosynthesis appears well conserved among land plants; however, different variants of anthocyanin-related genes between cultivars results in tissue-specific accumulations of purple pigments. Thus, broad genetic variations of anthocyanin profile, and tissue-specific distributions in carrot tissues and organs, can be observed, and the ratio of acylated to non-acylated anthocyanins varies significantly in the purple carrot germplasm. Additionally, anthocyanins synthesis can also be influenced by a wide range of external factors, such as abiotic stressors and/or chemical elicitors, directly affecting the anthocyanin yield and stability potential in food and beverage applications. In this study, we critically review and discuss the current knowledge on anthocyanin diversity, genetics and the molecular mechanisms controlling anthocyanin accumulation in carrots. We also provide a view of the current knowledge gaps and advancement needs as regards developing and applying innovative molecular tools to improve the yield, product performance and stability of carrot anthocyanin for use as a natural food colorant.

El quitosano potencializa la producción de compuestos fenólicos antioxidantes en zanahoria mediante un efecto sinérgico con el estrés de corte

In the present study, the postharvest application of wounding stress applied alone and combined with chitosan was evaluated as an innovative tool to increase the concentration of antioxidant phenolic compounds in carrots. Carrots were wounded to obtain pie-cuts and shreds. The whole and wounded tissue (300 g) was sprayed with a chitosan suspension (0.5% w/v), and the content of individual phenolics were evaluated before and after 48 h of storage at 20 °C. When the two stresses were combined (wounding+chitosan) a synergistic effect on the accumulation of phenolic compounds were obtained. For instance, after storage chlorogenic acid and p-coumaric acid derivative increased by 5,069.1% and 385%, respectively, in chitosan treated carrot shreds. Similarly, isocoumarin, which was not detected in carrots before storage, showed a high accumulation after storage in chitosan treated carrot shreds (1,074.8 mg/kg). Results presented herein demonstrated that the combination of wounding stress and chitosan can be used as an effective strategy to increase the content of antioxidant phenolic compounds in carrots. The stressed carrot tissue can be used as raw material to obtain value-added food products or for the extraction and purification of phenolics with application in the food and dietary supplement industries.

Effects of power ultrasound enhancement on infrared drying of carrot slices: Moisture migration and quality characterizations

To investigate the intensive effect of contacting ultrasound applied in infrared (IR) drying, a self-designed ultrasound-assisted IR (US-IR) dryer was developed, the water diffusion kinetics of carrot slices during hybrid US-IR drying was studied and the quality properties of dried products were evaluated. Results showed that the drying rates and rehydration ratios were significantly enhanced when the ultrasound was applied. Compared to pure IR dying, the drying durations shortened by 21%, 17%, and 11% for US-IR drying at 900, 1200, and 1500 W, respectively. The intensive effect of ultrasound increased the water activity when the moisture content of carrot slices decreased from 4.23 to 0.11 g water/g dry solids. The Deff values of US-IR dried samples were in the range of 8.09–26.98 × 10−10 m2/s, which were higher than the IR dried samples (6.34–22.92 × 10−10 m2/s). The micrographs showed the applied ultrasound created more porous structures to allow water migration from the inside of carrot tissue to the outside. Besides, ultrasound could be helpful to mitigate the formed dense layer on the surface of carrot slices during drying at high IR power.