Influence of fermentation conditions, and the blends of sorghum and carrot pulp supplementation on the nutritional and sensory quality of tef injera.

Tef [Eragrostis tef (Zucc.) Trotter], an ancient cereal primarily grown in Ethiopia, is becoming increasingly popular worldwide due to its high iron content and gluten-free nature. However, it has been reported that injera produced only with tef flour lack certain vital nutrients. Therefore, this specific study was conducted to supplement tef injera with other food materials of better nutritional value and compensate its expensive market price with sorghum cereal flour. The effect of fermentation conditions, and the sorghum and carrot pulp blending ratio on the nutritional value and sensory quality of tef injera was investigated. The factorial approach of the experimental design was conducted considering the nutritional value and sensory quality of the injera made of three main blending ratios of tef, sorghum, and carrot (60% tef: 30% sorghum: 10% carrot pulp, 45% tef: 45% sorghum: 10% carrot pulp and 30% tef: 60% sorghum: 10% carrot pulp) as experiential variables. The raw materials and injera were characterised for their proximate composition, physicochemical property, mineral composition, microbial analysis, and sensory attributes, using standard methods. The results of the study show that fermentation conditions and blending ratios have a significant effect on the nutritional, anti-nutritional, mineral content, microbial quality, and sensory properties of blended injera products, where higher values of ash, crude protein, crude fat, Total titratable acidity (TTA), Fe, Zn, and Ca (2.30%, 11.34%, 2.62%, 3.53, 32.97 mg/100 g, 2.98 mg/100 g and 176.85 mg/100 g, respectively) were analyzed for the co-fermented injera sample. In addition, a lower microbial count was observed in co-fermented injera samples, whereas microbial counts in injera samples prepared from carrot pulp-supplemented dough after the co-fermentation of tef and sorghum flours were observed to be higher. The injera product made using blending ratio of 60% tef: 30%sorghum: 10% carrot co-fermented was found to be the optimum result due to its very good nutritional improvement (i.e., reduction of some anti-nutritional factors, microbial contents, pH and increased contents of some minerals, crude protein, crude fat, TTA and improved most of the sensory quality of the supplemented injera product). According to this study, sorghum and carrot supplementation on tef could improve the nutritional value of injera while also providing an instant remedy for the growing price of tef.

Replication of single viruses across the kingdoms, Fungi, Plantae, and Animalia.

It is extremely rare that a single virus crosses host barriers across multiple kingdoms. Based on phylogenetic and paleovirological analyses, it has previously been hypothesized that single members of the family Partitiviridae could cross multiple kingdoms. Partitiviridae accommodates members characterized by their simple bisegmented double-stranded RNA genome; asymptomatic infections of host organisms; the absence of an extracellular route for entry in nature; and collectively broad host range. Herein, we show the replicability of single fungal partitiviruses in three kingdoms of host organisms: Fungi, Plantae, and Animalia. Betapartitiviruses of the phytopathogenic fungusRosellinia necatrix could replicate in protoplasts of the carrot (Daucus carota), Nicotiana benthamiana and Nicotiana tabacum, in some cases reaching a level detectable by agarose gel electrophoresis. Moreover, betapartitiviruses showed more robust replication than the tested alphapartitiviruses. One of the fungal betapartitiviruses, RnPV18, could persistently and stably infect carrot plants regenerated from virion-transfected protoplasts. Both alpha- and betapartitiviruses, although with different host preference, could replicate in two insect cell lines derived from the fall armyworm Spodoptera frugiperda and the fruit fly Drosophila melanogaster. Our results indicate the replicability of single partitiviruses in members of three kingdoms and provide insights into virus adaptation, host jumping, and evolution.

Evaluating the effects of mefenoxam on taxonomic and functional dynamics of nontarget fungal communities during carrot cultivation.

Ridomil Gold SL (45.3% a.i. mefenoxam) is a widely used chemical fungicide for the control of oomycetes. However, its impact on fungal communities remains unexplored. Therefore, the goal of this study was to examine the effects of mefenoxam on the temporal dynamics of fungal taxonomic and functional diversities during carrot cultivation under four treatment groups: mefenoxam application with and without Pythium inoculation, and untreated control groups with and without Pythium inoculation. Our in vitro sensitivity assay showed that the maximum recommended concentration of mefenoxam, 0.24 ppm, did not suppress the mycelial growth of P. irregulare. At 100 ppm, mycelial growth was only reduced by 11.4%, indicating that the isolate was resistant to mefenoxam. MiSeq sequencing data revealed transient taxonomic variations among treatments 2 weeks post-treatment. Mortierella dominated the fungal community in the mefenoxam-Pythium combination treatment, as confirmed through PCR using our newly designed Mortierella-specific primers. Conversely, mefenoxam-Pythium combination had adverse effects on Penicillium, Trichoderma, and Fusarium, and decrease the overall alpha diversity. However, these compositional changes gradually reverted to those observed in the control by the 12th week. The predicted ecological functions of fungal communities in all Pythium and mefenoxam treatments shifted, leading to a decrease in symbiotrophs and plant pathogen functional groups. Moreover, the community-level physiological profiling approach, utilizing 96-well Biolog FF microplates, showed discernible variations in the utilization of 95 diverse carbon sources among the treatments. Notably, arbutin, L-arabinose, Tween 80, and succinamic acid demonstrated a strong positive association with Mortierella. Our findings demonstrate that a single application of mefenoxam at its recommended rate triggers substantial taxonomic and functional shifts in the soil fungal community. Considering this impact, the conventional agricultural practice of repeated mefenoxam application is likely to exert considerable shifts on the soil ecosystem that may affect agricultural sustainability.

The Alternative Host with the Most: Understanding the Ecology of Xanthomonas hortorum pv. carotae on Noncarrot Crops in Central Oregon.

Bacterial blight of carrot, caused by Xanthomonas hortorum pv. carotae (Xhc), is an economically important disease in carrot (Daucus carota subsp. sativus) seed production. The objectives of this study were to determine if Xhc was present on noncarrot crops grown in central Oregon and, if detected, evaluate its ability to colonize alternative hosts. Surveys of three carrot seed fields and adjacent fields of rye (Secale cereale), alfalfa (Medicago sativa), parsley root (Petroselinum crispum var. tuberosum), and Kentucky bluegrass (Poa pratensis) demonstrated that Xhc was present on noncarrot crops. Greenhouse experiments were conducted to determine the ability of Xhc to colonize crops cultivated in the region. Carrot, alfalfa, curly parsley (Petroselinum crispum), Kentucky bluegrass, mint (Mentha × piperita), parsley root, roughstalk bluegrass (Poa trivialis), and wheat (Triticum aestivum) plants were spray-inoculated with Xhc and destructively sampled at 1, 7, 14, and 28 or 25 days post-inoculation. Xhc populations were quantified using viability quantitative PCR and dilution plating. A significant (P ≤ 0.03) effect of crop was observed at 1, 14, and 28 or 25 days in both experiments. While carrot hosted the most Xhc at the final timepoint, other crops supported epiphytic Xhc populations including wheat and both bluegrasses. Mint, parsley root, and alfalfa hosted the least Xhc. Bacterial blight symptoms were observed on carrots but not on noncarrot crops. This suggests that crops grown in central Oregon have the potential to be asymptomatically colonized by Xhc and may serve as reservoirs of the pathogen in carrot seed production systems.

Draft Genome Sequence of Carrot Alternaria Leaf Blight Pathogen Alternaria dauci.

The fungal genus Alternaria, which causes a variety of crop diseases, is widely distributed in the world. Alternaria leaf blight, caused by Alternaria dauci, is one of the most common and destructive diseases in carrot. The infection of A. dauci leads to dramatic decay on both foliage and taproot in severe cases, which results in significant yield losses. In this study, we sequenced and assembled the genome of A. dauci isolate CALB1, which isolated from the major carrot producing areas of China. A total of 65 contigs were assembled, and the estimated genome size was 34.9 Mb. The draft genome of A. dauci can be used for comparative genomic analysis of Alternaria species and provide genetic information for further research on plant-pathogen interactions.

Mathematical modeling of Escherichia coli O157:H7 growth in carrot juice influenced by Thymbra capitata essential oil, heat treatment, and storage temperature.

The aim of this study was to develop a mathematical model describing the survival of Escherichia coli O157:H7 in carrot juice treated with Thymbra capitata essential oil combined with mild heat treatment and stored at different temperatures. The viable count method was used to investigate the effect of the treatment on bacterial survival, and the response surface methodology was used to develop a statistical model fitting the data. The results showed that the variance of bacterial growth is explained by storage temperature (37 %) and heat treatment (35 %), these are followed by Thymbra capitata essential oil (18 %) and their interaction (9 %). Positive multiplicative interaction was obtained for any pair of the studied treatments and cooperative effect synergy was observed over a large domain of these factors. A mathematical model was successfully developed to describe Escherichia coli O157:H7 response to the selected factors, within the study limits, and to estimate the risk of juice contamination and shelf-life. Based on our results, the use of Thymbra capitata essential oil combined with heat treatment may control Escherichia coli O157:H7 growth in carrot juice stored at low temperature.

Assessing Carrot Accessions Susceptibility to the Bacterial Pathogen 'Candidatus Liberibacter solanacearum' and Its Associated Symptoms.

'Candidatus Liberibacter solanacearum' is an insect-transmitted bacterium associated with several plant diseases. In the Mediterranean Basin, 'Ca. L. solanacearum' haplotype D is vectored by Bactericera trigonica and can severely infect carrot plants leading to abnormal growth phenotypes and significant yield losses. Insecticide applications are insufficient to suppress disease spread and damage, and additional means for disease control are needed. In the current study, we evaluated the resistance of 97 carrot accessions to the bacterial pathogen 'Ca. L. solanacearum' and its associated symptoms. Accessions (Western and Asian types) were first screened in two commercial carrot fields. We found that Western type accessions were less prone to develop disease symptoms in both fields and were less frequently visited by the insect vector in one field. Overall, 22 Asian and five Western accessions with significantly lower disease incidence compared with the commercial cultivar were found. These accessions were then inoculated with 'Ca. L. solanacearum' under controlled conditions and were assessed for disease incidence, insect oviposition, and bacterial relative titer. Five accessions (three Asian and two Western) had significantly lower disease incidence compared with the reference cultivar. Interestingly, disease incidence was not necessarily in line with insect oviposition or in planta bacterial titer, which may indicate that other, perhaps physiological, differences among the accessions may govern the susceptibility of plants to the disease. The resistant accessions found in this study could be used in future resistance breeding programs and to better understand the underlying mechanisms of resistance to 'Ca. L. solanacearum'.

Fermented Carrot Pulp Regulates the Dysfunction of Murine Intestinal Microbiota.

It was the focus of attention that probiotic control drink was packed with prebiotic nutrients and lactic acid bacteria. So, this study is aimed at revealing that the fermented carrot pulp regulation and protection function to the intestinal microecological disorders usually induced by antibiotic treatment. First, we study on lactobacillus fermentation conditions and effects on the secondary metabolism of fermented carrot juice, get its phenolic acids up, and get its flavonoids down. Then, establishment of the dysbacteriosis mouse model was used to validate the fermented carrot pulp prevention and treatment of intestinal microbiota imbalance. After the antibiotic treatment, the mice showed impotence, laziness, slow movement, weight loss, thin feces, dull hair, and anal redness, while the mice in the control group were all normal in terms of the mental state, diet, weight, and bowl movement. Along with the treatment, the abnormal conditions of the mice in the model group and natural recovery group improved in different degrees, indicating that the fermentation treatment is of help to the intestinal microbiota recovery. The fermentation-treated group of mice recovered close to normal that the diarrhea disappeared, and the weight gain, mental state, and the feces became normal. The serum antioxidant (SOD, GSH, and MDA) levels of the mice were checked. The superoxide dismutase (SOD) levels and glutathione (GSH) levels in the ordinary fermentation-treated group and probiotic fermentation-treated group were significantly increased compare to the natural recovery group. The malondialdehyde (MDA) levels showed great differences between the fermentation-treated groups and the blank group. At last, the 16sRNA analysis revealed that the microbiota richness and diversity in probiotic fermentation (J) are much higher than those in the model group (H), ordinary fermentation group (I), and blank group (G). Groups J and I are of significantly higher antioxidant level than group H; however, only the glutathione (GSH) level in group J increased dramatically but not those in the other three groups. Antibiotic treatment-induced mouse intestinal microecological disorder reduce the microbiota richness and diversity. Prebiotics fermented carrot pulp treatment can help in the recovery from the microbiota richness and diversity level prior to the antibiotic treatment, which suggests it can regulate and protect the murine intestinal microbiome.

Effects of silicon dioxide, zinc oxide and titanium dioxide nanoparticles on Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani disease complex of carrot.

Foliar spray of silicon dioxide (SiO2 NPs), zinc oxide (ZnO NPs) and titanium dioxide (TiO2 NPs) nanoparticles were used for the management of Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani disease complex of carrot. Foliar spray of SiO2 NPs/ZnO NPs or TiO2 NPs increased plant growth attributes, chlorophyll and carotenoid of carrot. Foliar spray of 0.10 mg ml-1 SiO2 NPs caused the highest increase in plant growth, chlorophyll and carotenoid content of leaves followed by spray of 0.10 mg ml-1 ZnO NPs, 0.05 mg ml-1 SiO2 NPs, 0.05 mg ml-1 ZnO NPs, 0.10 mg ml-1 TiO2 NPs and 0.05 mg ml-1 TiO2 NPs. Use of SiO2 NPs caused a higher reduction in root galling, nematode multiplication and disease indices followed by ZnO NPs and TiO2 NPs. Two principal components analysis showed a total of 97.84% overall data variance in plants inoculated with single pathogen and 97.20% in plants inoculated with two or more pathogens. Therefore, foliar spray of SiO2 NPs appears interesting for the management of disease complex of carrot.

Dual Transcriptional Profiling of Carrot and 'Candidatus Liberibacter solanacearum' at Different Stages of Infection Suggests Complex Host-Pathogen Interaction.

The interactions between the phloem-limited pathogen 'Candidatus Liberibacter solanacearum' haplotype C and carrot (Daucus carota subsp. sativus) were studied at 4, 5, and 9 weeks postinoculation (wpi), by combining dual RNA-Seq results with data on bacterial colonization and observations of the plant phenotype. In the infected plants, genes involved in jasmonate biosynthesis, salicylate signaling, pathogen-associated molecular pattern- and effector-triggered immunity, and production of pathogenesis-related proteins were up-regulated. At 4 wpi, terpenoid synthesis-related genes were up-regulated, presumably as a response to the psyllid feeding, whereas at 5 and 9 wpi, genes involved in both the terpenoid and flavonoid production were down-regulated and phenylpropanoid genes were up-regulated. Chloroplast-related gene expression was down-regulated, in concordance with the observed yellowing of the infected plant leaves. Both the RNA-Seq data and electron microscopy suggested callose accumulation in the infected phloem vessels, likely to impair the transport of photosynthates, while phloem regeneration was suggested by the formation of new sieve cells and the upregulation of cell wall-related gene expression. The 'Ca. L. solanacearum' genes involved in replication, transcription, and translation were expressed at high levels at 4 and 5 wpi, whereas, at 9 wpi, the Flp pilus genes were highly expressed, suggesting adherence and reduced mobility of the bacteria. The 'Ca. L. solanacearum' genes encoding ATP and C4-dicarboxylate uptake were differentially expressed between the early and late infection stages, suggesting a change in the dependence on different host-derived energy sources. HPE1 effector and salicylate hydroxylase were expressed, presumably to suppress host cell death and salicylic acid-dependent defenses during the infection.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Effect of Agroecological Conditions on Biologically Active Compounds and Metabolome in Carrot.

Carrot serves as a source of health-beneficial phytochemicals for human diet whose content is affected by agroecological conditions. The effect of conventional, integrated and organic farming on ascorbic acid (AA) and α,ß-carotene levels of new carrot cultivars Cortina F1 and Afalon F1 was investigated and their metabolomic profiles were measured by direct analysis in real time ion source coupled with a high-resolution mass spectrometer (DART-HRMS). Cortina and Afalon exhibited high levels of AA and total carotenes under all agroecological conditions tested that fluctuated in broad ranges of 215-539 and 173-456 mg AA.kg-1 dry biomass and 1069-2165 and 1683-2165 mg carotene.kg-1 dry biomass, respectively. The ratio of ß- to α-carotene in both cultivars was about 1.3. The most important variable for the PCA and the partial least squares discriminant analysis (PLS-DA) models for ethyl acetate extracts measured in positive and negative ionization mode was 6-methoxymellein (6-MM). Total carotene content and 6-MM levels were higher in the organic carrot compared to the conventional one and were correlated with a higher level of spontaneous infection. Other important compounds identified were sitosterol, hexose and various organic acids including antioxidant ferulic and coumaric acids. The findings allow comparison of metabolomic profiles and the AA and carotene contents of both cultivars with those of other commercially used carrots.

'Candidatus Phytoplasma asteris' subgroups display distinct disease progression dynamics during the carrot growing season.

Aster Yellows phytoplasma (AYp; 'Candidatus Phytoplasma asteris') is an obligate bacterial pathogen that is the causative agent of multiple diseases in herbaceous plants. While this phytoplasma has been examined in depth for its disease characteristics, knowledge about the spatial and temporal dynamics of pathogen spread is lacking. The phytoplasma is found in plant's phloem and is vectored by leafhoppers (Cicadellidae: Hemiptera), including the aster leafhopper, Macrosteles quadrilineatus Forbes. The aster leafhopper is a migratory insect pest that overwinters in the southern United States, and historical data suggest these insects migrate from southern overwintering locations to northern latitudes annually, transmitting and driving phytoplasma infection rates as they migrate. A more in-depth understanding of the spatial, temporal and genetic determinants of Aster Yellows disease progress will lead to better integrated pest management strategies for Aster Yellows disease control. Carrot, Daucus carota L., plots were established at two planting densities in central Wisconsin and monitored during the 2018 growing season for Aster Yellows disease progression. Symptomatic carrots were sampled and assayed for the presence of the Aster Yellows phytoplasma. Aster Yellows disease progression was determined to be significantly associated with calendar date, crop density, location within the field, and phytoplasma subgroup.

The Actin Cytoskeleton Mediates Transmission of "Candidatus Liberibacter solanacearum" by the Carrot Psyllid.

Several vector-borne plant pathogens have evolved mechanisms to exploit and to hijack vector host cellular, molecular, and defense mechanisms for their transmission. In the past few years, Liberibacter species, which are transmitted by several psyllid vectors, have become an economically important group of pathogens that have devastated the citrus industry and caused tremendous losses to many other important crops worldwide. The molecular mechanisms underlying the interactions of Liberibacter species with their psyllid vectors are poorly studied. "Candidatus Liberibacter solanacearum," which is associated with important vegetable diseases, is transmitted by the carrot psyllid Bactericera trigonica in a persistent manner. Here, we elucidated the role of the B. trigonica Arp2/3 protein complex, which plays a major role in regulation of the actin cytoskeleton, in the transmission of "Ca Liberibacter solanacearum." "Ca Liberibacter solanacearum" colocalized with ArpC2, a key protein in this complex, and this colocalization was strongly associated with actin filaments. Silencing of the psyllid ArpC2 disrupted the colocalization and the dynamics of F-actin. Silencing of RhoGAP21 and Cdc42, which act in the signaling cascade leading to upregulation of Arp2/3 and F-actin bundling, showed similar results. On the other hand, silencing of ArpC5, another component of the complex, did not induce any significant effects on F-actin formation. Finally, ArpC2 silencing caused a 73.4% reduction in "Ca Liberibacter solanacearum" transmission by psyllids, strongly suggesting that transmission of "Ca Liberibacter solanacearum" by B. trigonica is cytoskeleton dependent and "Ca Liberibacter solanacearum" interacts with ArpC2 to exploit the intracellular actin nucleation process for transmission. Targeting this unique interaction could lead to the development of a novel strategy for the management of Liberibacter-associated diseases.IMPORTANCE Plant diseases caused by vector-borne pathogens are responsible for tremendous losses and threaten some of the most important agricultural crops. A good example is the citrus greening disease, which is caused by bacteria of the genus Liberibacter and is transmitted by psyllids; it has devastated the citrus industry in the United States, China, and Brazil. Here, we show that psyllid-transmitted "Candidatus Liberibacter solanacearum" employs the actin cytoskeleton of psyllid gut cells, specifically the ArpC2 protein in the Arp2/3 complex of this system, for movement and transmission in the vector. Silencing of ArpC2 dramatically influenced the interaction of "Ca Liberibacter solanacearum" with the cytoskeleton and decreased the bacterial transmission to plants. This system could be targeted to develop a novel approach for the control of Liberibacter-associated diseases.

Effect of ozone, lactic acid and combination treatments on the control of microbial and pesticide contaminants of fresh vegetables.

BACKGROUND: Fruit and vegetable consumption has increased due to their tremendous health benefits. However, recent studies have shown that contaminated products may serve as vehicles for foodborne pathogens and harmful chemicals. Therefore, fresh vegetables must be decontaminated before consumption to ensure food safety. RESULTS: In this study, the combined decontamination treatment of lactic acid (2.5 mL L-1 ) and ozone (9 mg L-1 ) for 10 min showed better efficacy in the removal of contaminants from fresh vegetables as compared to individual treatments. The combined treatment resulted in a reduction of 1.5-3.5 log CFU of native mesophilic bacteria per gram and 1.6-2.9 log CFU of artificially inoculated Escherichia coli per gram from tomato, cucumber, carrot and lettuce. The combined treatment also removed spiked pesticides, which represent artificial chemical contamination (28-97% chlorpyrifos and 62-100% λ-cyhalothrin residues), from fresh vegetables. No significant difference (P > 0.05) in various sensory attributes of vegetables was observed between untreated and treated (lactic acid and ozone) vegetables. CONCLUSIONS: The combination treatment provides a novel approach to target two groups of contaminants using a single procedure. The combination treatment can be used as an alternative to currently used decontamination techniques for the supply of safe vegetables to consumers. © 2020 Society of Chemical Industry.

Effect of different mineral salt mixtures and dough extraction procedure on the physical, chemical and microbiological composition of Salgam: A black carrot fermented beverage.

NaCl is utilized in Salgam at 1-2% (w/w). The aim of this study was to reduce the NaCl content by addition of different concentrations of KCl and CaCl2 during production and evaluate their effects on quality. An innovation in production process was also employed, specifically dough extraction and use of the resulting liquid as a starter inoculum. Lactic acid bacteria (LAB) species (13) were identified using a combined approach of (RAPD)-PCR and 16S rRNA gene sequencing. Lactobacillus paracasei and Lactobacillus plantarum were dominant, but Leuconostoc mesenteroides subsp. jonggajibkimchii, Lactococcus lactis subsp. cremoris, Lactobacillus coryniformis subsp. coryniformis, Lactobacillus paraplantarum were also found. Mineral compositons were determined using ICP-OES and the most abundant were potassium, sodium, calcium, magnesium and phosphorus, respectively. A mixture of NaCl and KCl protected anthocyanin contents and improved colour parameters. Dough extraction also accelerated production of salgam.

Robustness of fermented carrot juice against Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7.

Artisanal vegetable fermentations are regaining popularity in industrialized countries, but they could be prone to contamination with foodborne pathogens. By simulating home or small-scale restaurant fermentations, we evaluated the microbiological safety of spontaneous carrot juice fermentations. Raw carrot juice was spiked with Listeria monocytogenes, Salmonella enterica subsp. enterica Typhimurium and Escherichia coli O157:H7, and the microbial dynamics were followed throughout the entire fermentation process by cultivation and amplicon sequencing. In addition, the behavior of these pathogens was also monitored after addition of raw cucumber juice and storage under refrigerated conditions to mimic post-contamination issues. Although the numbers of the pathogens increased during the first phase of the fermentation, the pathogens were not able to persist throughout the fermentation. Their numbers fell below the detection limit after 8 days of fermentation at 20 °C. Further investigation using amplicon sequencing also showed that there was no major impact on the general microbial dynamics of the spontaneous carrot juice fermentation. This indicates that the artisanal carrot juice fermentation is a robust process which resists the persistence of pathogens. More caution is needed however when mixing the final fermented product with a raw juice. When simulating pathogen post-contamination, both Salmonella enterica and Escherichia coli were able to survive in the refrigerated fermented juice up to 10 days after the fermentation. Listeria monocytogenes was detected up to 8 days in the refrigerated juice. Pasteurization of the raw juice before adding it to the fermented product is thus recommended.

Changes in the core endophytic mycobiome of carrot taproots in response to crop management and genotype.

Fungal endophytes can influence production and post-harvest challenges in carrot, though the identity of these microbes as well as factors affecting their composition have not yet been determined, which prevents growers from managing these organisms to improve crop performance. Consequently, we characterized the endophytic mycobiome in the taproots of three carrot genotypes that vary in resistance to two pathogens grown in a trial comparing organic and conventional crop management using Illumina sequencing of the internal transcribed spacer (ITS) gene. A total of 1,480 individual operational taxonomic units (OTUs) were identified. Most were consistent across samples, indicating that they are part of a core mycobiome, though crop management influenced richness and diversity, likely in response to differences in soil properties. There were also differences in individual OTUs among genotypes and the nematode resistant genotype was most responsive to management system indicating that it has greater control over its endophytic mycobiome, which could potentially play a role in resistance. Members of the Ascomycota were most dominant, though the exact function of most taxa remains unclear. Future studies aimed at overcoming difficulties associated with isolating fungal endophytes are needed to identify these microbes at the species level and elucidate their specific functional roles.

Aliarcobacter vitoriensis sp. nov., isolated from carrot and urban wastewater.

Two isolates, one recovered from a carrot and another one from urban wastewater, were characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that both isolates clustered together, and were most closely related to Aliarcobacter lanthieri. Multilocus phylogenetic analysis (MLPA) using the concatenated sequences of five housekeeping genes (atpA, gyrA, gyrB, hsp60 and rpoB) suggested that these isolates formed a distinct phylogenetic lineage among the genera derived from the former genus Arcobacter. Whole-genome sequence, in silico DNA-DNA hybridization (isDDH) and the average nucleotide identity (ANI) value between the genome of strain F199T and those of related species confirmed that these isolates represent a novel species. These strains can be differentiated from its phylogenetically closest species A. lanthieri by its inability to growth on 1% glycine and by their enzyme activity of esterase lipase (C8) and acid phosphatase. Our results, by the application of a polyphasic analysis, confirmed that these two isolates represent a novel species of the genus Aliarcobacter, for which the name Aliarcobacter vitoriensis sp. nov. is proposed. The type strain is F199T (=CECT 9230T=LMG 30050T).

Evaluation and management of fungal-infected carrot seeds.

Carrot (Daucus carota L.), which is one of the 10 most important vegetable crops worldwide, is an edible root vegetable desired for its taste as well as its medicinal uses. However, a fungus isolated from carrot seeds was observed to substantially decrease the germination rate. The isolate was identified as Alternaria alternata based on morphological and molecular characteristics as well as a phylogenetic tree. The maximum seed infection rate of selected carrot cultivars was approximately 60%, with the main infection site just underneath the seed shell. Additionally, the germination rate of infected seeds decreased by 28.7%. However, the seed infection rate varied among the examined carrot cultivars. Regarding the effects of chemical fungicides, the optimal treatment involved immersing seeds in amistar top suspension concentrate (SC) (effective concentration of 0.65 g/L) for 6 h, which effectively killed the fungi inside the carrot seeds. The results of this study provide a theoretical basis for the development of efficient methods for preventing the infection of carrot seeds by specific fungi and increasing the germination rate and vigour index.

Crop management system and carrot genotype affect endophyte composition and Alternaria dauci suppression.

Managing pests in carrot production is challenging. Endophytic microbes have been demonstrated to improve the health and productivity of many crops, but factors affecting endophyte dynamics in carrot is still not well understood. The goal of this study was to determine how crop management system and carrot genotype interact to affect the composition and potential of endophytes to mitigate disease caused by Alternaria dauci, an important carrot pathogen. Twenty-eight unique isolates were collected from the taproots of nine diverse genotypes of carrot grown in a long-term trial comparing organic and conventional management. Antagonistic activity was quantified using an in vitro assay, and potential for individual isolates to mitigate disease was evaluated in greenhouse trials using two carrot cultivars. Results confirm that carrot taproots are colonized by an abundant and diverse assortment of bacteria and fungi representing at least distinct 13 genera. Soils in the organic system had greater total organic matter, microbial biomass and activity than the conventional system and endophyte composition in taproots grown in this system were more abundant and diverse, and had greater antagonistic activity. Carrot genotype also affected endophyte abundance as well as potential for individual isolates to affect seed germination, seedling growth and tolerance to A. dauci. The benefits of endophytes on carrot growth were greatest when plants were subject to A. dauci stress, highlighting the importance of environmental conditions in the functional role of endophytes. Results of this study provide evidence that endophytes can play an important role in improving carrot performance and mediating resistance to A. dauci, and it may someday be possible to select for these beneficial plant-microbial relationships in carrot breeding programs. Implementing soil-building practices commonly used in organic farming systems has potential to promote these beneficial relationships and improve the health and productivity of carrot crops.