Transcription-related metabolic regulation in grafted lemon seedlings under magnesium deficiency stress

Magnesium is one of the essential nutrients for plant growth, and plays a pivotal role in plant development and metabolism. Soil magnesium deficiency is evident in citrus production, which ultimately leads to failure of normal plant growth and development, as well as decreased productivity. Citrus is mainly propagated by grafting, so it is necessary to fully understand the different regulatory mechanisms of rootstock and scion response to magnesium deficiency. Here, we characterized the differences in morphological alterations, physiological metabolism and differential gene expression between trifoliate orange rootstocks and lemon scions under normal and magnesium-deficient conditions, revealing the different responses of rootstocks and scions to magnesium deficiency. The transcriptomic data showed that differentially expressed genes were enriched in 14 and 4 metabolic pathways in leaves and roots, respectively, after magnesium deficiency treatment. And the magnesium transport-related genes MHX and MRS2 may respond to magnesium deficiency stress. In addition, magnesium deficiency may affect plant growth by affecting POD, SOD, and CAT enzyme activity, as well as altering the levels of hormones such as IAA, ABA, GA3, JA, and SA, and the expression of related responsive genes. In conclusion, our research suggests that the leaves of lemon grafted onto trifoliate orange were more significantly affected than the roots under magnesium-deficient conditions, further indicating that the metabolic imbalance of scion lemon leaves was more severe.

Transcriptome differential expression analysis of defoliation of two different lemon varieties

'Allen Eureka' is a bud variety of Eureka lemon with excellent fruiting traits. However, it suffers from severe winter defoliation that leads to a large loss of organic nutrients and seriously affects the tree's growth and development as well as the yield of the following year, and the mechanism of its response to defoliation is still unclear. In order to investigate the molecular regulatory mechanisms of different leaf abscission periods in lemon, two lemon cultivars ('Allen Eureka' and 'Yunning No. 1') with different defoliation traits were used as materials. The petiole abscission zone (AZ) was collected at three different defoliation stages, namely, the pre-defoliation stage (CQ), the mid-defoliation stage (CZ), and the post-defoliation stage (CH). Transcriptome sequencing was performed to analyze the gene expression differences between these two cultivars. A total of 898, 4,856, and 3,126 differentially expressed genes (DEGs) were obtained in CQ, CZ, and CH, respectively, and the number of DEGs in CZ was the largest. GO analysis revealed that the DEGs between the two cultivars were mainly enriched in processes related to oxidoreductase, hydrolase, DNA binding transcription factor, and transcription regulator activity in the defoliation stages. KEGG analysis showed that the DEGs were concentrated in CZ and involved plant hormone signal transduction, phenylpropanoid biosynthesis, glutathione metabolism, and alpha-linolenic acid metabolism. The expression trends of some DEGs suggested their roles in regulating defoliation in lemon. Eight gene families were obtained by combining DEG clustering analysis and weighted gene co-expression network analysis (WGCNA), including β-glucosidase, AUX/IAA, SAUR, GH3, POD, and WRKY, suggesting that these genes may be involved in the regulation of lemon leaf abscission. The above conclusions enrich the research related to lemon leaf abscission and provide reliable data for the screening of lemon defoliation candidate genes and analysis of defoliation pathways.

Composite coatings of beeswax + naphthalene acetic acid preserved fruit quality and antioxidants in stored lemon fruits

Lemon fruits are well recognized for their richness in antioxidants. The present study was conducted to maintain the antioxidant properties of lemon fruits under long term cold storage. Fruits were given different treatments of naphthalene acetic acid (NAA) @ 50, 100 and 150 ppm plus beeswax (BW) @ 2% and were stored at 6-8 °C and 90-95% RH for 60 days. At the end of storage, fruits coated with NAA (50 ppm) + BW (2%) retained 42.14 and 34.61% antioxidants, 62.72 and 56.54% phenolic content and 17.72 and 13.80% hydroxyl radical scavenging capacity in peel and pulp, respectively as compared to the control. This treatment also resulted in lesser weight loss (5.27%), higher ascorbic acid content (46.31 mg 100 ml-1 juice) and titratable acidity (5.23%). Hence, NAA + BW coatings were promising for the maintenance of the postharvest antioxidant quality of stored lemons.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01364-4.

Survival of Listeria monocytogenes and Salmonella in citrus storage waxes or on lemons held under common commercial storage conditions

To prolong cold storage, diluted storage waxes are applied to washed lemons after harvest and before packing, without drying steps, to reduce premature rotting and water loss. The survival of Listeria monocytogenes and Salmonella in undiluted and diluted storage waxes (S1-S4), and on lemon surfaces under common commercial storage were investigated. Populations of L. monocytogenes declined more slowly than Salmonella in undiluted storage waxes over 24 h of storage at 4 or 22 °C. L. monocytogenes (inoculated at ∼6 log CFU/mL) was detected by enrichment in undiluted waxes S2, S3, and S4 after 75-135 days at 4 °C but not after 30, 10, or 105 days, respectively at 22 °C. L. monocytogenes survived better in diluted than in undiluted storage waxes at 22 °C. Populations of L. monocytogenes (∼6 log CFU/lemon) declined by 0.64-1.62 log on lemon surfaces right after waxing. Populations of L. monocytogenes decreased to <1.30 log CFU/lemon after 28 days (1:9 S1) or 75 days (other treatments) at 12 °C and ≥93% RH. Except for 1:9 S1, L. monocytogenes was detected by enrichment in all lemon samples over 87 days of storage. Packinghouses should consider the survival of L. monocytogenes and Salmonella in citrus storage waxes in their food safety programs.

From nose to brain: The effect of lemon inhalation observed by whole brain voxel to voxel functional connectivity

Lemon fragrance is known for its stimulating properties, but its mechanisms of action are not well known yet. This study aimed to examine the effect of lemon essential oil inhalation on healthy participants' alertness level and their neural correlates using magnetic resonance imaging (MRI). Twenty-one healthy men underwent functional MRI scans in different conditions: a resting state condition, a condition where they were exposed to passive lemon smelling (alternating exposure to lemon and breathing fresh air), and a control condition without lemon fragrance diffusion -the order of the last two conditions being randomized. Alertness levels were assessed immediately after each condition using the Karolinska Sleepiness Scale. Voxel-wise whole-brain global functional connectivity and graph theory analyses were computed to investigate brain functional connectivity and network topology alterations. After lemon fragrance inhalation, we observed a higher level of alertness as compared to resting state -but not compared to control condition. During lemon fragrance inhalation, we found increased global functional connectivity in the thalamus, paralleled by decreased global connectivity in several cortical regions such as precuneus, postcentral and precentral gyrus, lateral occipital cortex and paracingulate gyrus. Graph theory analysis revealed increased network integration in cortical regions typically involved in olfaction and emotion processing such as olfactory bulb, hypothalamus and thalamus, while decreased network segregation in several regions of the posterior part of the brain during olfaction as compared to resting state. The present findings suggest that lemon essential oil inhalation could increase the level of alertness.

Ionic liquid-enhanced lemon biomass carbon dots with sustainable use in bionic antibody microspheres for urea capture and ethyl carbamate inhibition

Herein, we reported the room-temperature fabrication of ionic liquid-modified carbon dots encapsulated in bionic antibodies (IL-modified CDs@BAs) by one-pot green synthesis. In order to enhance the fluorescence intensity of CDs, imidazole ILs and lemon rich in heteroatoms were selected as CDs modifiers and sources. The resulting IL-modified CDs@BAs showed good selectivity and capture toward urea and obviously induced fluorescence quenching by template-binding. The inhibition rate ofIL-modified CDs@BAs on the urea pathway of ethyl carbamate was about 29.07% in the simulated Huangjiu system, indicating a good inhibitory effect. The IL-modified CDs@BAs system was also reproducible after five consecutive uses, thus reducing the economic cost. This research would expand the application fields of BAs-based optical sensing system from the perspectives of energy conservation, environmental protection and resource recovery, focusing on their application in the field of food safety control.

Quantitative metabolomic analysis reveals the fractionation of active compounds during lemon fruit juicing

In this study, metabolomic analysis was employed to investigate the separation (fractionation) of active compounds into lemon juice (LJ) and lemon pomace (LP) during lemon juicing. A total of 968 metabolites were identified, and 438 differentially abundant metabolites (DAMs) were screened out between LJ and LP, suggesting significant metabolite fractionation during juicing. The "flavonoids", "phenolic acids", and "saccharides and alcohols" were mainly retained in the LP, while the fractionation of major "organic acids" was differentiated. Seven of the 12 potential bitter metabolites were more abundant in the LP and two were more abundant in the LJ, suggesting that LP would be more bitter. L-Ascorbic acid, thiamine, and acitretin were significantly lost during juicing, while riboflavin was newly dissolved during juicing. The antioxidant capacity of LP was significantly higher than that of LJ, which was closely related to the higher abundance of phenolic acid metabolites in LP. These findings suggtested that promoting the release of flavonoids and phenolic acids from LP is a potential strategy to improve the quality of LJ. Results also provides important information and reference for developing high-value products by using LP.

Analysis of Energy Use Efficiency and Greenhouse Gas Emissions of Lemon (Citrus lemon L.) Production in Turkey

The purpose of this study was to determine the energy use efficiency and greenhouse gas emissions of lemon production. It was performed during the 2019-2020 production period in Turkey. The agricultural inputs and outputs used in lemon production were calculated to determine the energy use efficiency and greenhouse gas emissions. According to study findings, the energy inputs in lemon production were calculated respectively as 16,046.98 MJ ha-1 (55.43%) chemical fertilizers energy, 4168.93 MJ ha-1 (14.40%) chemicals energy, 2815.20 MJ ha-1 (9.72%) electricity energy, 2740.42 MJ ha-1 (9.47%) diesel fuel energy, 1864.80 MJ ha-1 (6.44%) irrigation water energy, 705.67 MJ ha-1 (2.44%) machinery energy and 610.20 MJ ha-1 (2.11%) human labour energy. Total input energy and output energy were calculated as 28,952.20 MJ ha-1 and 60,165.40 MJ ha-1, respectively. Energy use efficiency, specific energy, energy productivity and net energy values were calculated respectively as 2.08, 0.91 MJ kg-1, 1.09 kg MJ-1 and 31,213.20 MJ ha-1. The consumed total energy inputs in lemon production can be categorized as 27.74% direct, 72.26% indirect, 8.55% renewable and 91.45% non-renewable. Total greenhouse gas emissions were calculated as 2650.96 kgCO2‑eqha-1 for lemon production, with the greatest share for nitrogen 950.62 kgCO2‑eqha-1 (35.86%). Based on the study findings, it was concluded that lemon production in 2019-2020 production season was profitable in terms of energy use efficiency (2.08). Greenhouse gas emission ratio (per kg) was calculated as 0.08. This study is important since there is no study on the energy balance and greenhouse gas emissions in lemon production in Muğla province, Turkey.

Assessing the effectiveness of green synthesized zinc oxide nanoparticles in controlling multidrug-resistant clinical bacteria

Multi-drug resistant pathogenic bacteria are life threaten agent associated with the misuse and overuse of antibiotics. The biological synthesis of metal oxide nanoparticles is a promising alternative treatment. The current study reported the synthesis of zinc oxide nanoparticles (ZnONPs) using different plants extracts of garlic (Allium sativum), ginger (Zingiber officinale), and lemon (Citrus lemon). The plant extracts not only acts as reducing agents but as stabilizing agents for the produced nanoparticles. Biosynthesized zinc oxide nanoparticles (ZnONPs) were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray studies (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and ultraviolet-visible (UV-vis) spectroscopy. XRD analysis confirmed the production of pure ZnONPs. UV-vis spectroscopy revealed the presence of ZnONPs and reported the characteristic absorption peak of ZnONPs at 370 nm. SEM and TEM confirmed the shape and size of nanoparticles, with an average mean size of 0.3-11.40 nm. This study reported the antibacterial activity and minimum inhibitory concentration of biosynthesized ZnONPs using the broth microdilution method against some clinical pathogenic bacteria. This study also reported the antimicrobial activity of ZnONPs prepared with garlic extract against Enterococcus sp. and Pseudomonas sp. While, those prepared with ginger extract were effective against Enterococcussp. and methicillin-resistant Staphylococcus aureus. ZnONPs synthesized by garlic extract were more powerful and effective than ZnONPs synthesized by ginger and lemon extracts.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01048-3.

Larvicidal effects of some essential oils against Aedes aegypti (L.), the vector of dengue fever in Saudi Arabia

Essential oils are very popular among organic growers because they are ecologically safe, do not have mammalian toxicity, and cannot be resistant to a variety of contaminants. Four essential oils, Lemon, Lavender, Peppermint, and Neem, were tested for larvicide efficacy against the dengue fever vector Aedes aegypti larvae under laboratory conditions using dipping bioassay techniques. Among the essential oils tested, lemon, peppermint, and lavender oils showed high larvicidal activity against larvae of Ae. aegypti. Lemon oil showed the highest effects (LC₅₀ 10.676 ppm), while Peppermint, Lavender and Neem oil showed the lowest effects (LC₅₀ 21.380, 29.818 and 38.058 ppm, respectively). As a result, the mixture of lemon oil (LC₅₀) with Peppermint oil (LC₂₅) showed the highest co-toxicity factor, whereas the mixture of Lemon oil (LC₅₀) with Diesel oil (LC₂₅) showed the lowest co-toxicity factor. Based on the results of this study, it appears that essential oils may be useful as larvicides against Ae. aegypti larvae. In search of new natural larvicides, these compounds may provide an alternative to Synthetic insecticides as these are environmentally safe insecticides.

In vitro comparison of natural tooth-whitening remedies and professional tooth-whitening systems

Background

An increasing number of patients are using natural homemade remedies such as strawberries, banana peels, coconut oil rinse, basil, lemon, activated charcoal, apple cider vinegar, baking soda, and turmeric to obtain whiter teeth. However, studies on these natural whitening products are limited.

Aim

To evaluate the effectiveness of different homemade tooth-whitening agents in vitro.

Materials and methods

Ninety caries-free extracted anterior and premolar teeth were collected, cleaned, and sectioned at the roots. The teeth were mounted in epoxy resin (buccal surface) and stored in 0.2 % thymol solution, and were treated with one of the following six whitening agents: baking soda, activated charcoal, lemon juice, strawberries, Colgate Optic Whitening toothpaste, and Opalescence 20 % home-bleaching system. The enamel shade in each sample was measured four times using a spectrophotometer. Baseline measurements for ΔE and (L*, a*, b*) were obtained, and the second measurement was obtained after 5 days. The third reading was obtained on the 10th day, and the fourth reading was obtained at the 4th week to measure colour stability. One-way analysis of variance and post-hoc Tukey tests were used for statistical analysis.

Results

ΔE measurements showed a significant difference on the 10th day in all groups except the lemon group (P = 0.164), while all groups showed a statistically significant difference at the 4th week. The mean colour change differed remarkably between the first and fourth readings. The highest change was observed in the lemon group (44.0 ± 2.9), closely followed by the Opalescence 20 % and Colgate Optic Whitening toothpaste groups. The lowest change was observed with strawberries (38.2 ± 4.8). ΔE showed a significant difference in all groups except the turmeric group.

Conclusion

Statistically significant differences were obtained with baking soda, activated charcoal, strawberries, lemon juice, Colgate Optic Whitening toothpaste, and Opalescence 20%. Further studies are required to evaluate the effects of these agents on surface roughness and colour stability.

Salinity level influenced morpho-physiology and nutrient uptake of young citrus rootstocks

Soil and irrigation water salinity are major limiting factor to citrus industry in arid environments. The objective of this study was to assess the effects of different salt stress levels on growth and ion uptake of three-month-old citrus rootstocks; sour orange (Citrus aurantium) and Volkamer lemon (Citrus volkameriana). Six levels of NaCl-salinity were used, 0.7 (control), 2, 4, 8, 12 and 15 dS m^-1. Salinity increment from 2.0 to 15.0 dS m^-1 significantly reduced seedlings height, stem diameter, leaf area, root dry weight, leaf relative water content, chlorophyll content index and chlorophyll fluorescence by one to three folds. In addition, leaf and root N concentration reduced by 10%-50%, P 6%-50%, K 8%-47%, Ca⁺² 7%-51% and Mg⁺² 7%-50% when salt stress in the irrigation water increased from 2.0 to 15.0 dS m^-1. Conversely, salt stress increment (2.0-15.0 dS m^-1) increased leaf stomatal resistance (5 folds), proline concentration (1 fold), Na⁺ and Cl^- in the leaf (10 fold) and root (4 fold) when compared to control (0.7 dS m^-1). In term of rootstock, Volkamer had higher seedling height, stem diameter, and root constituents (length, fresh and dry weight) than sour orange. While sour orange had higher leaf Cl^-, Ca⁺² and Mg⁺², Volkamer lemon had higher N, Na⁺, K⁺, and P. However, root nutrient (N, Na⁺, Cl^-, P and Mg⁺²) from Volkamer had consistently higher concentration compared to sour orange at 4.0, 8.0, 12.0 and 15.0 dS m^-1. Therefore, we believe that the Volkamer rootstock is more tolerant to salt stress than sour orange.

Reduction of SARS-CoV-2 viral load in exhaled air by antiseptic chewing gum: a pilot trial

PURPOSE

The dominant route of transmission of SARS-CoV-2 is airborne, through respiratory transmission by aerosols or droplets which can be measured by viral load in exhaled air. Several natural substances have shown antiviral activity. The aim of this pilot study was to investigate the effect of a chewing gum containing natural antiseptic ingredients (cinnamon-, peppermint- and lemon-oil, quercetin, spermidine, ginger and ginseng) on viral load in exhalative air in patients infected with SARS-CoV-2.

METHODS

Nine patients infected with SARS-CoV-2 were enrolled and exhaled forcefully into a special mouthpiece at different time points before and after chewing the antiseptic gum. The mouthpiece contained a filter paper serving for extraction of coronaviruses following real-time PCR to quantify the viral load.

RESULTS AND CONCLUSION

Cycle threshold (Ct) values of all patients increased after chewing the gum. The mean difference between the Ct values at baseline (before chewing the antiseptic gum) and time point 30 min (15 min after chewing) was 3.8 ± 2.6; (93% viral load reduction; p = 0.002). Time point 15 min (2.7 ± 1.7 (83% viral load reduction; p = 0.003)), 60 min (3.0 ± 3.4 (88% viral load reduction; p = 0.028)), 90 min (3.7 ± 1.8 (92% viral load reduction; p = 0.004)) and 120 min (3.0 ± 3.7 (91% viral load reduction; p = 0.05)) showed similar results. The antiseptic chewing gum demonstrated a significant potential to reduce SARS-CoV-2 viral load in exhalative air and, in this way, reduce further spread and infection risk. Larger placebo-controlled clinical trials are required to confirm these findings further.

First Report of Postharvest Blue Mold decay caused by Penicillium expansum on Lemon (Citrus limon) fruit in China

Lemon (Citrus limon) is one of the most important commercial (both dried and fresh) citrus fruits in China. In the spring of 2019, postharvest blue mold decay was observed at an incidence of 3-5% on lemon fruit at the local markets in Beijing, China. Fruit lesions were circular, brown, soft, and watery, and rapidly expanded at 25°C. To isolate the causal organism, small pieces (2 mm3) were cut from the lesions, surface-sterilized for 1 min in 1.5% NaOCl, rinsed three times with sterilized water, dried with sterile filter paper, placed onto potato dextrose agar (PDA) medium, and incubated at 25°C for 6 days. Eight morphologically similar single-colony fungal isolates were recovered from six lemon fruit. Colony surfaces were bluish-green on the upper surface and cream to yellow-brown one the reverse. Hyphae on colony margins were entirely subsurface and cream in color. Mycelium was highly branched, septate, and colorless, and conidiophores were 250 to 450 × 3.0 to 4.0 µm in size. Stipe of conidiophores were smooth-walled, bearing terminal penicilli, typically terverticillate or less commonly birverticillate, rami occurring singly, 16 to 23 × 3.0 to 4.0 µm, metulae in 3 to 6, measuring 12 to 15 × 3.0 to 4.0 µm. Phialides were ampulliform to almost cylindrical, in verticils of 5 to 8, measuring 8 to 11 × 2.5 to 3.2 µm with collula. Conidia were smooth-walled, ellipsoidal, measuring 3.0 to 3.5 × 2.5 to 3.0 µm. According to morphological characteristics, the fungus was identified as Penicillium expansum (Visagie et al. 2014). For molecular identification, genomic DNA of eight fungal isolates was extracted, regions of the beta-tubulin (TUB), and calmodulin (CAL) genes and ITS region, were amplified using Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 primers respectively. Obtained sequences of all isolates were identical to sequences of the representative isolate YC-IK12, which was submitted in the GenBank. BLAST results of YC-IK12 sequences (ITS; MT856700: TUB; MT856958: CAL; MT856959) showed 98 to 100% similarity with P. expansum accessions (NR-077154, LN896428, JX141581). For pathogenicity tests, 10 μl of conidial suspension (10 × 105 conidia/ml) from seven-day-old YC-IK12 culture was inoculated using a sterilized needle into the surface of each five asymptomatic disinfected lemons. As a control, three lemons were inoculated using sterile distilled water. All inoculated lemons were placed in plastic containers and incubated at 25°C for 7 days. Decay lesions, identical to the original observations, developed on all inoculated lemons, while control lemons remained asymptomatic. Fungus re-isolated from the inoculated lemon was identified as P. expansum on the basis morphology and Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 sequences. Previously, Penicillium spp. including P. expansum have been reported as post-harvest pathogens on various Citrus spp. (Louw & Korsten 2015). However, P. digitatum has been reported on lemons and P. expansum has been reported on stored Kiwifruit (Actinidia arguta), Malus, and Pyrus species in China (Tai, 1979; Wang et al. 2015). To our knowledge, this is the first report of blue mold caused by P. expansum on lemons in China. References Louw, J. P., Korsten, L. 2015. Plant Dis. 99:21-30. Tai, F.L. 1979. Sylloge Fungorum Sinicorum. Sci. Press, Acad. Sin., Peking, 1527 pages. 8097 Visagie, C.M. et al. 2014. Studies. Mycol.78: 343. Wang, C. W. et al. 2015. Plant Dis. 99:1037.

Addition of lemon before boiling chlorinated tap water: A strategy to control halogenated disinfection byproducts

Chlorine disinfection is required to inactivate pathogens in drinking water, but it inevitably generates potentially toxic halogenated disinfection byproducts (halo-DBPs). A previous study has reported that the addition of ascorbate to tap water before boiling could significantly decrease the concentration of overall halo-DBPs in the boiled water. Since the fruit lemon is rich in vitamin C (i.e., ascorbic acid), adding it to tap water followed by heating and boiling in an effort to decrease levels of halo-DBPs was investigated in this study. We examined three approaches that produce lemon water: (i) adding lemon to tap water at room temperature, termed "Lemon"; (ii) adding lemon to boiled tap water (at 100 °C) and then cooling to room temperature, termed "Boiling + Lemon"; and (iii) adding lemon to tap water then boiling and cooling to room temperature, termed "Lemon + Boiling". The concentrations of total and individual halo-DBPs in the resultant water samples were quantified with high-performance liquid chromatography-tandem mass spectrometry and the cytotoxicity of DBP mixtures extracted from the water samples was evaluated using human epithelial colorectal adenocarcinoma Caco-2 cells and hepatoma HepG2 cells. Our results show that the "Lemon + Boiling" approach substantially decreased the concentrations of halo-DBPs and the cytotoxicity of tap water. This strategy could be applied to control halo-DBPs, as well as to lower the adverse health effects of halo-DBPs on humans through tap water ingestion.

Physical Activity and Natural Products and Minerals in the SARS-CoV-2 Pandemic: An Update

Coronavirus-disease 19 (COVID-19) has rapidly become a global public health issue, and there is a desperate need for strategies of prevention, reduction, and treatment to halt the epidemic. The coronavirus affects the immune system, and individuals with a compromised immune system, such as those with diabetes, hypertension, obesity, are more susceptible to this virus. Lifestyle-related variables such as physical activity and nutritional supplements can decrease inflammatory markers, increase anti-inflammatory and antioxidant status, and improve the immune system. Lifesty-lerelated variables play preventive roles against various infectious diseases including COVID-19. This review highlights the effects of physical activity and nutrients supplements on the immune system and their possible benefits in combating the harms caused by infection with the COVID-19 virus.

Inducing mutations in Citrus spp.: Sensitivity of different sources of plant material to gamma radiation

Gamma radiation represents an alternative for improving genotypes for which breeding through hybridization involves many difficulties because of their complex reproductive biology, as in the case of citrus. In this study in vitro and ex vitro mutagenesis was induced by gamma radiation in several citrus species ('Alemow' and sour orange as citrus rootstocks, lemon cv. 'Fino 49' and 'Verna 51', mandarin cv. 'Nova' and lime cv. 'Bearss'). Three different sources of materials - seeds, budwoods and nodal segments - from in vitro explants, were tested. Seeds and budwoods were germinated or induced to sprout, and de novo regeneration was obtained from in vitro nodal segments from which preexisting buds were previously removed. Budwoods were tested in summer and winter in order to assess their capacity for mutation and further sprouted in different seasons. Seeds were seen to be more resistant to gamma radiation (LD₅₀ of 127 Gy in 'Alemow and 156 Gy in sour orange) than budwoods (LD₅₀ about 50 Gy for all cultivars) and nodal segments (LD₅₀ about 25 Gy for both lemon cultivars), the last being the most sensitive material tested. Similar LD₅₀ were found for budwoods collected in winter and summer for all the genotypes. All the tested plant material can be considered suitable for gamma irradiation, although budwood is the most widely available and tissue culture material needs the highest degree of expertise.

Effect of colchicine induced tetraploidy on morphology, cytology, essential oil composition, gene expression and antioxidant activity of Citrus limon (L.) Osbeck

Citrus limon (L.) Osbeck cultivated all over the world is a valuable source of aromatic essential oil. To develop tetraploids of C. limon, four different concentration of colchicine (0.025, 0.05, 0.1 and 0.2%; w/v) and three varied exposure time (12, 24 and 48 h) were employed. The ploidy level of diploids (2n = 2x = 18) and tetraploids (2n = 4x = 36) were determined by direct chromosome count and confirmed by flow cytometric analyses. Successful result with maximum tetraploidy frequency was observed in plantlets developed from seeds treated with 0.025% colchicine for 24 h. Morphological and stomatal characteristics indicated that tetraploids were taller with increased leaf and root length. On the other side, the leaves of tetraploids had fewer and larger stomata with a greater number of chloroplasts in guard cells in contrast with diploids. GC-GC/MS analyses showed cyclic monoterpene, limonene had increased significantly in tetraploids and was further confirmed by HPLC quantification. RT-PCR analyses revealed unaltered expression of monoterpene synthase, sesquiterpene synthase and flavone synthase and remarkable upregulation of genes such as limonene synthase, chalcone synthase and phenylalanine ammonia lyase in tetraploids. Antioxidant activity of essential oil of tetraploids was higher than diploids in all the five test systems studied. Overall, the findings of the present study prove that colchicine induced tetraploidy in C. limon could be a greater source of essential oil with improved composition and of economic significance.

Study on the effect of citric acid adaptation toward the subsequent survival of Lactobacillus plantarum NCIMB 8826 in low pH fruit juices during refrigerated storage

Pre-treatment of stationary phase cells of Lactobacillus plantarum NCMIB 8826 with citric acid (pH 3 to 6) for a short period of time significantly improved subsequent cell survival in several highly acidic fruit juices namely cranberry (pH 2.7), pomegranate (pH 3.5), and lemon & lime juices (pH 2.8). Although the mechanism for this adaptation is still unclear, the analysis of the cellular fatty acid content of acid adapted cells and the reverse transcription polymerase chain reaction (RT-PCR) showed a significant increase (by ~1.7 fold) of the cellular cyclopropane fatty acid, cis-11,12-methylene octadecanoic acid (C_19:0cyclow7c) and a significant upregulation (~12 fold) of cyclopropane synthase (cfa) were observed, respectively, during acid adaptation. It is likely that these changes led to a decrease in membrane fluidity and to lower membrane permeability, which prevents the cells from proton influx during storage in these low pH fruit juices.

New food approaches to reduce and/or eliminate increased gastric acidity related to gastroesophageal pathologies

OBJECTIVE

Gastroesophageal reflux disease is very common in industrialized countries and rapidly and significantly increasing even in developing countries. The approach in this study is one not commonly found to date in the scientific literature. To assess the ability of reduced-carbohydrate diets and foods that are enriched with acid potential of hydrogen (pH; lemon and tomato) to quickly and exponentially reduce symptoms that are related to conditions such as gastritis and gastroesophageal reflux and unrelated to Helicobacter pylori.

METHODS

After the administration of an anamnestic test, 130 patients were selected including 73 women and 57 men, 21 to 67 y, and with a gastritis diagnosis for 92 patients (56 women, 36 men) and reflux gastritis for 38 patients (17 women, 21 men). Study participants followed three dietary treatments in succession. Each treatment lasted 2 wk and treatments were separated by 2 wk of washout. The patients followed a diet that consisted primarily of proteins and fats and included the exponential reduction of glycides (simple and complex). In addition, the treatment provided for the daily intake of the juice of two lemons and approximately 100 g of fresh orange tomato without seeds eaten either raw or cooked and peeled.

RESULTS

During treatment and at the end of 2 wk of treatment, the patients reported significant improvements including an almost total disappearance of symptoms that were related to the disease in question.

CONCLUSIONS

This study shows that a carbohydrate-free diet and/or highly hypoglycidal diet that is enriched with acid pH foods appears to lead to a decrease in the pH of the gastric contents, thus inhibiting the further production of hydrochloric acid with a reduction or disappearance of heartburn symptoms that are typical of gastroesophageal diseases.

Effects of addition of different fibers on rheological characteristics of cake batter and quality of cakes

The aim of this study was to investigate the effects of addition of dietary fibers on rheological properties of batter and cake quality. Wheat flour was replaced by 5 and 10% (wt%) oat, pea, apple and lemon fibers. All cake batters showed shear thinning behavior. Incorporation of fibers increased consistency index (k), storage modulus (G') and loss modulus (G″). As quality parameters, specific volume, hardness, weight loss, color and microstructure of cakes were investigated. Cakes containing oat and pea fibers (5%) had similar specific volume and texture with control cakes which contained no fiber. As fiber concentration increased, specific volume decreased but hardness increased. No significant difference was found between weight loss of control cake and cakes with oat, pea and apple fibers. Lemon fiber enriched cakes had the lowest specific volume, weight loss and color difference. When microstructural images were examined, it was seen that control cake had more porous structure than fiber enriched cakes. In addition, lemon and apple fiber containing cakes had less porous crumb structure as compared to oat and pea containing ones. Oat and pea fiber (5%) enriched cakes had similar physical properties (volume, texture and color) with control cakes.

A novel component from citrus, ginger, and mushroom family exhibits antitumor activity on human meningioma cells through suppressing the Wnt/β-catenin signaling pathway

Recurrent meningiomas constitute an uncommon but significant problem after standard (surgery and radiation) therapy failure. Current chemotherapies (hydroxyurea, RU-486, and interferon-α) are only of marginal benefit. There is an urgent need for more effective treatments for meningioma patients who have failed surgery and radiation therapy. Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM are some of the plant derivatives that have anti-tumorgenic properties and cause cell death in meningioma cells in vitro. Due to its ease of administration, long-term tolerability, and low incidence of long-term side effects, we explored its potential as a therapeutic agent against meningiomas by examining their efficacy in vitro against meningioma cells. Treatment effects were assessed using MTT assay, Western blot analysis, caspases assay, and DNA fragmentation assay. Results indicated that treatments of IOMM-Lee and CH157MN meningioma cells with Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM induced apoptosis with enhanced phosphorylation of glycogen synthase kinase 3 β (GSK3β) via inhibition of the Wnt5/β-catenin pathway. These drugs did not induce apoptosis in normal human neurons. Other events in apoptosis included downregulation of tetraspanin protein (TSPAN12), survival proteins (Bcl-XL and Mcl-1), and overexpression apoptotic factors (Bax and caspase-3). These results provide preliminary strong evidence that medicinal plants containing Limonin, Tangeritin, 6-Gingerol, Zerumbone, Ganoderic Acid A, and Ganoderic Acid DM can be applied to high-grade meningiomas as a therapeutic agent, and suggests that further in vivo studies are necessary to explore its potential as a therapeutic agent against malignant meningiomas.

Citron and lemon under the lens of HR-MAS NMR spectroscopy

High Resolution Magic Angle Spinning (HR-MAS) is an NMR technique that can be applied to semi-solid samples. Flavedo, albedo, pulp, seeds, and oil gland content of lemon and citron were studied through HR-MAS NMR spectroscopy, which was used directly on intact tissue specimens without any physicochemical manipulation. HR-MAS NMR proved to be a very suitable technique for detecting terpenes, sugars, organic acids, aminoacids and osmolites. It is valuable in observing changes in sugars, principal organic acids (mainly citric and malic) and ethanol contents of pulp specimens and this strongly point to its use to follow fruit ripening, or commercial assessment of fruit maturity. HR-MAS NMR was also used to derive the molar percentage of fatty acid components of lipids in seeds, which can change depending on the Citrus species and varieties. Finally, this technique was employed to elucidate the metabolic profile of mold flavedo.

Effect of Melia azedarach (Sapindales: Meliaceae) fruit extracts on Citrus Leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae)

Melia azedarach L. extracts were studied in comparison with selected biorational insecticides against the citrus leafminer Phyllocnistis citrella Stainton under field conditions. Citrus limon (L.) Burm. F. trees were exposed to: Melia extracts of green and mature fruits, Neem oil (30% a.i.), abamectin (1.8% a.i.) and control. Two sprays of each treatment (except for Melia mature fruit extract) were executed at 10-d intervals. The live number of the 1^st and later (2^nd & 3^rd) larval instars per leaf were recorded at initial sampling date and at 10-d intervals after each spray application. Results indicated that there were significant differences in the number of live larval instars among treatments. Melia extracts and the two biorationals, neem oil and abamectin, decreased the larvae population significantly to lower numbers than that of the control at 10 days after each spray application. However, the decrease caused by neem oil and abamectin was significantly higher than that of Melia extracts. Thus, these extracts might be considered as potential alternative with other biorational control methods in management of the leafminer. Further research including bioassays is needed to determine the factors responsible for reducing larvae population and whether these Melia extracts can be utilized in future citrus IPM programs as a tool for citrus leafminer management.

Effect of cation exchange resin treatment and addition on sugar as anti-caking agent on retention of nutritional and sensory quality of lemon juice powder during storage

Lemon juices clarified with enzymatic treatment with and without cation exchange resin treatment were concentrated to 60(o) Brix in a vacuum evaporator and converted into powders by foam mat drying technique. Powders obtained from cation exchange resin treated juice were better in quality with respect to acidity, glucose, fructose, sugars, and ascorbic acid contents as compared to those prepared form non treated juice. Further, during 9 months storage, the powders suffered slight loss of acidity, and increase in reducing sugars i.e. glucose and fructose and considerable loss (31-55%) in vitamin C contents. Storage conditions did not bring about any significant change in the ash and hesperidin content of the product. But some losses were registered in the total phenols (23.69%) and sensory quality (from 7.72 to 7.26) of the powders. Further, the powders prepared from cation exchange resin treated juice and those pulverized with cane sugar suffered overall lesser changes in most of the quality parameters during 9 months of storage, thus indicating that, the treatment of lemon juice with cation exchange resin is beneficial for better initial product quality and pulverization of prepared powder with cane sugar is beneficial in reducing the hygroscopicity and retention of quality in a better way.