Previous studies have indicated that there may be differences among the varieties of lemon flavonoids, but the details have not yet been made clear, which limits the comprehensive use of different cultivated lemon varieties. In this study, ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS) and ultraviolet-visible spectroscopy (UV-Vis) were used to investigate the types and contents of flavonoids in the flesh of the main cultivated variety (Eureka) and five common lemon varieties, as well as their in vitro antioxidant activity. A total of 21 compounds were identified, five of which were common compounds. Among them, Verna, Lisbon, and Bearss each have characteristic components that can serve as potential criteria for variety identification. Each of the six varieties of lemon has strong antioxidant activity. The antioxidant activity of different lemon varieties is related to flavonoids. Therefore, Eureka and the other five varieties of lemon are good natural antioxidants, and the cultivation and industrial production of lemons should consider the needs and selection of suitable varieties.

Citrus Huanglongbing (HLB), caused by the phloem-inhibiting bacterium Candidatus Liberibacter asiaticus (CLas), is the most devastating citrus disease, intimidating citrus production worldwide. Although commercially cultivated citrus cultivars are vulnerable to CLas infection, HLB-tolerant attributes have, however, been observed in certain citrus varieties, suggesting a possible pathway for identifying innate defense regulators that mitigate HLB. By adopting transcriptome and small RNAome analysis, the current study compares the responses of HLB-tolerant lemon (Citrus limon L.) with HLB-susceptible Shatangju mandarin (Citrus reticulata Blanco cv. Shatangju) against CLas infection. Transcriptome analysis revealed significant differences in gene expression between lemon and Shatangju. A total of 1751 and 3076 significantly differentially expressed genes were identified in Shatangju and lemon, respectively. Specifically, CLas infected lemon tissues demonstrated higher expressions of genes involved in antioxidant enzyme activity, protein phosphorylation, carbohydrate, cell wall, and lipid metabolism than Shatangju. Wet-lab experiments further validated these findings, demonstrating increased antioxidant enzyme activity in lemon: APX (35%), SOD (30%), and CAT (64%) than Shatangju. Conversely, Shatangju plants exhibited higher levels of oxidative stress markers like H2O2 (44.5%) and MDA content (65.2%), alongside pronounced ion leakage (11.85%), than lemon. Moreover, microscopic investigations revealed that CLas infected Shatangju phloem exhibits significantly more starch and callose accumulation than lemon. Furthermore, comparative sRNA profiles revealed the potential defensive regulators for HLB tolerance. In Shatangju, increased expression of csi-miR166 suppresses the expression of disease-resistant proteins, leading to inadequate defense against CLas. Conversely, reduced expression of csi-miR166 in lemon plants enables them to combat HLB by activating disease-resistance proteins. The above findings indicate that when infected with CLas, lemon exhibits stronger antioxidative activity and higher expression of disease-resistant genes, contributing to its enhanced tolerance to HLB. In contrast, Shatangju shows lower antioxidative activity, reduced expression of disease-resistant genes, significant ion leakage, and extensive callose deposition, possibly related to damage to plant cell structure and blockage of phloem sieve tubes, thereby promoting the development of HLB symptoms.

Lemon is a fruit rich in antioxidant properties and has several health benefits, namely the reduction of skin edema and anticarcinogenic properties, which are due to its high content of bioactive compounds. Melatonin can improve and preserve the properties of lemon for longer and also has health benefits. The aim of this study was to evaluate the effects of oral administration of lemon juice after melatonin treatment on murinometric parameters of wild-type (WT) mice and transgenic mice carrying human papillomavirus (HPV). Two trials were performed for oral administration of the lemon extract compound: in drinking water and in diet. First of all, lemons were treated by immersion with melatonin at 10 mM. Then, lemons were squeezed, and the juice obtained was freeze-dried and stored to be subsequently added to drinking water or diet, according to the assay. Thus, mice were divided into eight groups in the drink assay (each with n = 5): group 1 (G1, WT, control), group 2 (G2, WT, 1 mL lemon), group 3 (G3, WT, 1.5 mL lemon), group 4 (G4, WT, 2 mL lemon), group 5 (G5, HPV16, control), group 6 (G6, HPV16, 1 mL lemon) group 7 (G6, HPV16, 1.5 mL lemon) and group 8 (G6, HPV16, 2 mL lemon). The diet assay was divided into four groups: group 1 (G1, WT, control), group 2 (G2, WT, 4 mL lemon), group 3 (G3, HPV16, control) and group 4 (G4, HPV16, 4 mL lemon). In the drink assay, the highest concentration of melatonin (308 ng/100 mL) was for groups 4 and 8, while in the food assay, there was only one concentration of melatonin (9.96 ng/g) for groups 2 and 4. Both trials lasted 30 days. During this time, body weight, food and water were recorded. Afterward, they were sacrificed, and samples were collected for different analyses. At the concentrations used, the lemon juice with melatonin had no adverse effects on the animals\' health and showed a positive outcome in modifying weight gain and enhancing antioxidant activity in mice. Moreover, a reduction in the incidence of histological lesions was observed in treated animals. Further research is needed to better understand the effects of lemon extract on health and treatment outcomes in this animal model.

UNASSIGNED: Tracheal intubation is a common technique used to secure a patient\'s airway, which is crucial in anesthesia. Successful tracheal intubation depends on various factors, including the assessment of the patient\'s airway before the procedure. In recent years, scoring systems, such as LEMON (an acronym for the assessment of the airway\'s appearance, identification of any dental issues, evaluation of Mallampati classification, assessment of airway obstruction, and examination of neck mobility) and intubation difficulty scale (IDS) have gained attention. This study aimed to investigate the relationship between the LEMON criteria and IDS in tracheal intubation. The goal was to provide valuable insights that can assist medical professionals in optimizing their approach to airway management by analyzing clinical data, assessing patient outcomes, and evaluating the consistency between these scoring systems.
UNASSIGNED: This study was based on a descriptive-analytical study involving a group of patients requiring intubation. This study examined 105 patients scheduled for elective surgeries, aged between 19 and 60 years, without specific underlying diseases, such as laryngeal cancer, temporomandibular joint stiffness, or significant tongue enlargement, and with a body mass index (BMI) below 40 kg/m². Initially, expert anesthesiologists assessed the patients using the LEMON criteria, and then the degree of intubation difficulty was measured using the IDS scoring system. Finally, these two criteria were compared.
UNASSIGNED: In this study, there was a significant correlation between the LEMON score and the IDS score (P < 0.001). The difficult intubation group (IDS score higher than 0) had higher LEMON scores (with the highest score equal to 4) than the non-difficult intubation group (IDS score of 0) (P = 0.017). The average LEMON and IDS scores were 3.11 and 1.35, respectively. Among the participants, 96.2% had an intubation difficulty score of ≤ 5; nevertheless, 3.8% had a score of > 5. Additionally, limited neck mobility emerged as the sole independent predictor of intubation difficulty (P = 0.002, odds ratio = 6.152).
UNASSIGNED: The LEMON score is associated with difficult intubation in adult patients requiring intubation.

\'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.

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.

Citrus fruits are among the most economically important crops in the world. In the global market, the Citrus peel is often considered a byproduct but substitutes an important phenotypic characteristic of the fruit and a valuable source of essential oils, flavonoids, carotenoids, and phenolic acids with variable concentrations. The Mediterranean basin is a particularly dense area of autochthonous genotypes of Citrus that are known for being a source of healthy foods, which can be repertoires of valuable genes for molecular breeding with the focus on plant resistance and quality improvement. The scope of this study was to characterize and compare the main phenotypic parameters (i.e., peel thickness, fruit volume, and area) and levels of bioactive compounds in the peel of fruits from the local germplasm of Citrus in Greece, to assess their chemodiversity regarding their polyphenolic, volatile, and carotenoid profiles. A targeted liquid chromatographic approach revealed hesperidin, tangeretin, narirutin, eriocitrin, and quercetin glycosides as the major polyphenolic compounds identified in orange, lemon, and mandarin peels. The content of tangeretin and narirutin followed the tendency mandarin > orange > lemon. Eriocitrin was a predominant metabolite of lemon peel, following its identification in lower amounts in mandarin and at least in the orange peel. For these citrus-specific metabolites, high intra- but also interspecies chemodiversity was monitored. Significant diversity was found in the essential oil content, which varied between 1.2 and 3% in orange, 0.2 and 1.4% in mandarin, and 0.9 and 1.9% in lemon peel. Limonene was the predominant compound in all Citrus species peel essential oils, ranging between 88 and 93% among the orange, 64 and 93% in mandarin, and 55 and 63% in lemon cultivars. Carotenoid analysis revealed different compositions among the Citrus species and accessions studied, with β-cryptoxanthin being the most predominant metabolite. This large-scale metabolic investigation will enhance the knowledge of Citrus peel secondary metabolite chemodiversity supported by the ample availability of Citrus genetic resources to further expand their exploitation in future breeding programs and potential applications in the global functional food and pharmaceutical industries.

The lemon industry in the Mediterranean basin is strongly threatened by \"mal secco\" disease (MSD) caused by the fungus Plenodomus tracheiphlilus. Leaf pretreatments with Pseudomonas mediterranea 3C have been proposed as innovative tools for eco-sustainable interventions aimed at controlling the disease. In this study, by exploiting the results of previously performed RNAseq analysis, WCGNA was conducted among gene expression patterns in both inoculated (Pt) and pretreated and fungus-inoculated lemon plants (Citrus limon L.) (3CPt), and two indicators of fungal infection, i.e., the amount of fungus DNA measured in planta and the disease index (DI). The aims of this work were (a) to identify gene modules significantly associated with those traits, (b) to construct co-expression networks related to mal secco disease; (c) to define the effect and action mechanisms of P. mediterranea by comparing the networks. The results led to the identification of nine hub genes in the networks, with three of them belonging to receptor-like kinases (RLK), such as HERK1, CLAVATA1 and LRR, which play crucial roles in plant-pathogen interaction. Moreover, the comparison between networks indicated that the expression of those receptors is not induced in the presence of P. mediterranea, suggesting how powerful WCGNA is in discovering crucial genes that must undergo further investigation and be eventually knocked out.

Background The interest in natural remedies is increasing rapidly as they can serve as alternatives to synthetic drugs and reduce their potential side effects. Current research is focused on examining the antioxidant and anti-inflammatory characteristics of a combination of Cucumis sativus and Citrus macroptera extract in an in-vitro context. The combination of citrus, cucumber, and glycerol extract could serve as an effective alternative to synthetic antioxidants and anti-inflammatory drugs and lower the side effects of the available synthetic drugs. This extract can be used to treat potentially malignant oral disorders like oral leukoplakia, oral submucous fibrosis, and oral lichen planus, which are attributed to its antioxidant properties. Aim To evaluate the anti-inflammatory and antioxidant activity of formulation of C. sativus, C. macroptera, and glycerol extract. Materials and methods The cucumber and citrus fruits were separated, cleaned, and dried. The cucumber was then peeled, its seeds cleaned, and the pulp cut into pieces. Using a laboratory mortar and pestle, a 5 ml extract was prepared. The citrus fruit was cut in half, its seeds were removed, and a 5 ml extract was prepared from their pulp only. These two extracts were combined to form a 10 ml extract solution with 8 ml of glycerol. The extracts were combined, shaken for 24 hours, filtered, and stored at 4°C. Assays like the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, Hydrogen Peroxide (H2O2) assay, Bovine serum albumin (BSA) assay, and Egg albumin (EA) denaturation assay were performed to assess their anti-inflammatory and antioxidant properties. Results The antioxidant and anti-inflammatory properties of the extract showed comparable activity (percentage of inhibition: 76% in BSA and EA assays; 90% in DPPH and H2O2 assays) to that of the standard values (percentage of inhibition: 78% in BSA and EA assays; 92% in DPPH and H2O2 assays) at concentrations 30, 40, and 50 µl in the BSA assay, EA assay, DPPH, and H2O2 assay. The maximum concentration at which the antioxidant and anti-inflammatory effects were appreciable was 50 µl in all assays.  Conclusion This study concluded that the combination of cucumber, citrus, and glycerol extract could serve as an effective alternative to synthetic antioxidants and anti-inflammatory drugs currently available. These extracts can provide a promising solution in the field of drug development for treating lesions caused by free radicals and oxidative stress in the oral cavity.

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