Kumquat essential oil decreases proliferation and activates JNK signaling and apoptosis in HT-1080 fibrosarcoma cells.

Kumquats are small citrus fruits produced by the Fortunella japonica tree. In addition to its aroma, kumquat essential oil may have antiproliferative effects; however, research on the effects of kumquat essential oil on human cell lines is limited. This study investigated the effects of kumquat essential oil on the proliferation of three human cell lines (HT-1080 fibrosarcoma cells, HeLa cervical adenocarcinoma cells, and CUA-4 normal human fibroblasts). As the concentration of kumquat essential oil increased, cell proliferation and viability, as measured by MTT activity assays, decreased in all three cell lines. Compared to untreated cells, HT-1080 fibrosarcoma cells exposed to kumquat essential oil exhibited an increased presence of phosphorylated JNK. Apoptosis was also stimulated, as PARP cleavage of treated HT-1080 fibrosarcoma cells was detected. Use of a JNK inhibitor resulted in decreased PARP cleavage in HT-1080 cells following treatment with kumquat EO, suggesting that activity of JNK is implicated in the stress response. The kumquat essential oil constituents limonene and myrcene both independently led to decreased proliferation and apoptosis.

Red light-induced kumquat fruit coloration is attributable to increased carotenoid metabolism regulated by FcrNAC22.

Carotenoids play vital roles in the coloration of plant tissues and organs, particularly fruits; however, the regulation of carotenoid metabolism in fruits during ripening is largely unknown. Here, we show that red light promotes fruit coloration by inducing accelerated degreening and carotenoid accumulation in kumquat fruits. Transcriptome profiling revealed that a NAC (NAM/ATAF/CUC2) family transcription factor, FcrNAC22, is specifically induced in red light-irradiated fruits. FcrNAC22 localizes to the nucleus, and its gene expression is up-regulated as fruits change color. Results from dual luciferase, yeast one-hybrid assays and electrophoretic mobility shift assays indicate that FcrNAC22 directly binds to, and activates the promoters of three genes encoding key enzymes in the carotenoid metabolic pathway. Moreover, FcrNAC22 overexpression in citrus and tomato fruits as well as in citrus callus enhances expression of most carotenoid biosynthetic genes, accelerates plastid conversion into chromoplasts, and promotes color change. Knock down of FcrNAC22 expression in transiently transformed citrus fruits attenuates fruit coloration induced by red light. Taken together, our results demonstrate that FcrNAC22 is an important transcription factor that mediates red light-induced fruit coloration via up-regulation of carotenoid metabolism.

Determination of five pesticides in kumquat: Dissipation behaviors, residues and their health risk assessment under field conditions.

The present study was carried out to profile the dissipation patterns and residues of five pesticides (triazophos, profenofos, chlorpyrifos, etoxazole and bifenthrin) on kumquat using QuEChERS method coupled with HPLC-MS/MS. The corresponding dietary health risks were also estimated. In the method validation, satisfactory results of good linearity (r2 ≥ 0.9956), sensitivity (limits of quantification ≤0.01 mg/kg), recoveries (71.0-95.7%) with relative standard deviations (0.70-9.4%) were obtained. The half-lives of the five pesticides in kumquat were 13.6-38.5 d under field conditions according to first-order kinetics. Based on the final residue experiment, dietary exposure risks of profenofos, chlorpyrifos, etoxazole and bifenthrin were all acceptably low, with RQc and RQa values of 0.00199-0.122 and 0.00145-0.200, respectively. However, exposure intake of triazophos posed unacceptable acute and chronic health risks for Chinese residents, especially for children with RQa and RQc up to 4.25 and 2.19. Forbidden use suggestion of triazophos and recommended MRLs of profenofos and bifenthrin were put forward in kumquat for safe production and consumption. This work was significant in providing guidance on appropriate application and MRL establishment of pesticides in kumquat.

Identification of genes associated with soluble sugar and organic acid accumulation in 'Huapi' kumquat (Fortunella crassifolia Swingle) via transcriptome analysis.

BACKGROUND: The levels and ratios of sugar and acid are important contributors to fruit taste. Kumquat is one of the most economically important citrus crops, but information on the soluble sugar and organic acid metabolism in kumquat is limited. Here, two kumquat varieties - 'Rongan' (RA) and its mutant 'Huapi' (HP) - were used to assess soluble sugar and organic acid accumulation and the related genes. RESULTS: Soluble sugars include sucrose, glucose and fructose, while malate, quinic acid and citrate are the dominant organic acids in the fruits of both kumquat varieties. HP accumulated more sugars but fewer organic acids than did RA. Transcriptome analysis revealed 63 and 40 differentially expressed genes involved in soluble sugar and organic acid accumulation, respectively. The genes associated with sugar synthesis and transport, including SUS, SPS, TST, STP and ERD6L, were up-regulated, whereas INVs, FRK and HXK genes related to sugar degradation were down-regulated in HP kumquat. For organic acids, the up-regulation of PEPC and NAD-MDH could accelerate malate accumulation. In contrast, high expression of NAD-IDH and GS resulted in citric acid degradation during HP fruit development. Additionally, the PK, PDH, PEPCK and FBPase genes responsible for the interconversion of soluble sugars and organic acids were also significantly altered in the early development stages in HP. CONCLUSION: The high sugar accumulation in HP fruit was associated with up-regulation of SUS, SPS, TST, STP and ERD6L genes. The PEPCK, PEPC, NAD-MDH, NADP-IDH, GS and FBPase genes played important roles in acid synthesis and degradation in HP kumquat. These findings provide further insight into understanding the mechanisms underlying metabolism of sugars and organic acids in citrus. © 2021 Society of Chemical Industry.

Effects of Soil Amendments on Soil Pb Bioavailability and Pb Absorption by a low-Pb Accumulator Kumquat Grown in Two Types of Pb-Contaminated Soils.

A pot experiment was conducted to investigate the effects of 0.5% and 1% alkaline, clay mineral and phosphorus amendments, as well as 2% and 5% organic amendments, on lead (Pb) soil bioavailability and Pb absorption by the low-Pb accumulator kumquat (Citrus japonica Thunb.) 'Cuipi' in two typical Pb-contaminated soils, Jiyuan and Yangshuo, from northern and southern China, respectively. The diethylenetriaminepentaacetic acid-extractable Pb soil concentration and Pb accumulation in kumquat significantly decreased with amendment additions. High amendment doses had greater inhibitory effects than low doses but no significant effects on the kumquat's biomass in the two typical soils. Alkaline, but not clay mineral, amendments greatly increased the soil pH level. Organic amendments effectively reduced Pb accumulation owing to their strong adsorptive capacities. Thus, using organic amendments combined with a low-Pb accumulator kumquat forms a suitable farming practice for producing safe fruit in the two common types of Pb-contaminated soils in China.

Biological Activities and Safety of Citrus spp. Essential Oils.

Citrus fruits have been a commercially important crop for thousands of years. In addition, Citrus essential oils are valuable in the perfume, food, and beverage industries, and have also enjoyed use as aromatherapy and medicinal agents. This review summarizes the important biological activities and safety considerations of the essential oils of sweet orange (Citrus sinensis), bitter orange (Citrus aurantium), neroli (Citrus aurantium), orange petitgrain (Citrus aurantium), mandarin (Citrus reticulata), lemon (Citrus limon), lime (Citrus aurantifolia), grapefruit (Citrus × paradisi), bergamot (Citrus bergamia), Yuzu (Citrus junos), and kumquat (Citrus japonica).

Functionality of kumquat (Fortunella margarita) in the production of fruity ice cream.

BACKGROUND: The aim of this study was to investigate the effect of kumquat (Fortunella margarita) on the quality characteristics of ice cream. Kumquat paste (KP) was added to an ice cream mix at four concentrations, 0 (control), 5, 10 and 15% (w/w), for ice cream production. RESULTS: The increment of KP level caused an increase in acidity, vitamin C content, b* value and overrun value compared with the control ice cream. The apparent viscosity of samples decreased with the addition of KP at concentrations of 5 and 10% compared with the control. Results indicated that lyophilized water extract of KP (LKE) contained remarkable phenolic compounds. It was observed that LKE exhibited moderate in vitro antioxidant capacity. KP enhanced the color, flavor, vitamin C content and Mg and K contents of the ice cream. The addition of KP positively affected the sensory properties. CONCLUSION: KP may be used as a suitable source of natural color and flavor agent in ice cream production. KP enhanced the vitamin C content and Mg and K contents of ice cream and improved its sensory properties.

FcWRKY70, a WRKY protein of Fortunella crassifolia, functions in drought tolerance and modulates putrescine synthesis by regulating arginine decarboxylase gene.

WRKY comprises a large family of transcription factors in plants, but most WRKY members are still poorly understood. In this study, we report functional characterization of a Group III WRKY gene (FcWRKY70) from Fortunella crassifolia. FcWRKY70 was greatly induced by drought and abscisic acid, but slightly or negligibly by salt and cold. Overexpression of FcWRKY70 in tobacco (Nicotiana nudicaulis) and lemon (Citrus lemon) conferred enhanced tolerance to dehydration and drought stresses. Transgenic tobacco and lemon exhibited higher expression levels of ADC (arginine decarboxylase), and accumulated larger amount of putrescine in comparison with wild type (WT). Treatment with D-arginine, an inhibitor of ADC, caused transgenic tobacco plants more sensitive to dehydration. Knock-down of FcWRKY70 in kumquat down-regulated ADC abundance and decreased putrescine level, accompanied by compromised dehydration tolerance. The promoter region of FcADC contained two W-box elements, which were shown to be interacted with FcWRKY70. Taken together, our data demonstrated that FcWRKY70 functions in drought tolerance by, at least partly, promoting production of putrescine via regulating ADC expression.

Effect of kumquat (Fortunella crassifolia) pericarp on natural killer cell activity in vitro and in vivo.

Natural killer (NK) cells play a key role in innate immune defense against infectious disease and cancer. A reduction of NK activity is likely to be associated with increased risk of these types of disease. In this study, we investigate the activation potential of kumquat pericarp acetone fraction (KP-AF) on NK cells. It is shown to significantly increase IFN-γ production and NK cytotoxic activity in human KHYG-1 NK cells. Moreover, oral administration of KP-AF significantly improves both suppressed plasma IFN-γ levels and NK cytotoxic activity per splenocyte in restraint-stressed mice. These results indicate that raw kumquat pericarp activates NK cells in vitro and in vivo. To identify the active constituents, we also examined IFN-γ production on KHYG-1 cells by the predicted active components. Only ß-cryptoxanthin increased IFN-γ production, suggesting that NK cell activation effects of KP-AF may be caused by carotenoids such as ß-cryptoxanthin.

Comparison of lipids, fatty acids and volatile compounds of various kumquat species using HS/GC/MS/FID techniques.

BACKGROUND: Kumquat (Fortunella spp.) is one of the important fruit species that has been introduced into Turkey recently. It is well adapted to the Mediterranean region in Turkey. Early research of kumquat was started on adaptation and pomological traits, and only a few studies have been concerned with chemical content. After understanding the health benefits of kumquat fruits farmers started their plantations in Turkey. Thus in this study the fruits of five kumquat species - Fortunella margarita (Lour.) Swingle, F. crassifolia Swingle, F. obovata Hort. ex Tanaka, F. hindsii (Champ. ex Benth.) Swingle, and limequat [Citrus aurantifolia × F. japonica (Thumb.)] - were compared based on their lipids, fatty acids and volatile profiles. The lipids, fatty acids and volatile profiles were determined by using gas chromatography with flame ionisation detection (GC/FID) and headspace gas chromatography mass spectrometry (HS-GC/MS) techniques. Volatile constituents of kumquat fruits were isolated by a headspace method. RESULTS: The total lipid content (%) of kumquat species ranged from 0.26% to 0.37%. The polyunsaturated fatty acids were detected in a higher amount compared to the monounsaturated fatty acids and saturated fatty acids, respectively. The headspace technique led to the identification of 39 compounds and among a total of 39 constituents identified, d-limonene was the most abundant compound, comprising 67.78-88.72%. The results indicated that kumquats are rich in dietary and health benefits. CONCLUSION: Thirty-nine compounds were identified and terpenes were the major chemical group in all kumquat genotypes. Esters, alcohols, aldehydes and ketones were also detected. The present study revealed that the kumquat fruits have a valuable levels of health beneficial chemo-preventive effects and genotypes varied based on their lipid, fatty acids and volatile constituents.

Kumquat peel-derived biochar to support zeolitic imidazole framework-67 (ZIF-67) for enhancing peracetic acid activation to remove acetaminophen from aqueous solution.

This study presents the synthesis of a novel composite catalyst, ZIF-67, doped on sodium bicarbonate-modified biochar derived from kumquat peels (ZIF-67@KSB3), for the enhanced activation of peracetic acid (PAA) in the degradation of acetaminophen (APAP) in aqueous solutions. The composite demonstrated a high degradation efficiency, achieving 94.3% elimination of APAP at an optimal condition of 200 mg L-1 catalyst dosage and 0.4 mM PAA concentration at pH 7. The degradation mechanism was elucidated, revealing that superoxide anion (O2•-) played a dominant role, while singlet oxygen (1O2) and alkoxyl radicals (R-O•) also contributed significantly. The degradation pathways of APAP were proposed based on LC-MS analyses and molecular electrostatic potential calculations, identifying three primary routes of transformation. Stability tests confirmed that the ZIF-67@KSB3 catalyst retained an 86% efficiency in APAP removal after five successive cycles, underscoring its durability and potential for application in pharmaceutical wastewater treatment.

Determination, Quality, and Health Assessment of Pesticide Residues in Kumquat in China.

Pesticide residues in kumquat fruits from China, and the quality and chronic/acute intake risks in Chinese consumers, were assessed using the QuEChERS procedure and UHPLC-MS/MS and GC-MS/MS methods. Our 5-year monitoring and survey showed 90% of the 573 samples of kumquat fruits collected from two main production areas contained one or multiple residual pesticides. Overall, 30 pesticides were detected, including 16 insecticides, 7 fungicides, 5 acaricides, and 2 plant growth modulators, of which 2 pesticides were already banned. Two or more residual pesticides were discovered in 81% of the samples, and pesticide residues in 9.4% of the samples surpassed the MRLs, such as profenofos, bifenthrin, triazophos, avermectin, spirodiclofen, difenoconazole, and methidathion. The major risk factors on the safety of kumquat fruits before 2019 were profenofos, bifenthrin, and triazophos, but their over-standard frequencies significantly declined after 2019, which was credited to the stricter supervision and management policies by local governments. Despite the high detection rates and multi-residue occurrence of pesticides in kumquat fruits, about 81% of the samples were assessed as qualified. Moreover, the accumulative chronic diet risk determined from ADI is very low. To better protect the health of customers, we shall formulate stricter organic phosphorus pesticide control measures and stricter use guidelines, especially for methidathion, triazophos, chlorpyrifos, and profenofos. This study provides potential data for the design of kumquat fruit quality and safety control guidelines and for the reduction in health risks to humans.

Effectiveness of kumquat decoction for the improvement of cough caused by SARS-CoV-2 Omicron variants, a multicentre, prospective observational study.

BACKGROUND: Kumquat decoction is a traditional Chinese medicine formula and has been widely used to alleviate the coronavirus disease 2019 (COVID-19)-related cough in China. However, the effectiveness and safety of kumquat decoction remain unclear. PURPOSE: To assess the effectiveness and safety of kumquat decoction for COVID-19-related cough. STUDY DESIGN: A multicentre, prospective observational study. METHODS: We enrolled consecutive patients with mild-to-moderate COVID-19 from December 31, 2022, to January 3, 2023, during the Omicron phase in Yangshuo County, China. The primary outcome was the time from study baseline to sustained cough resolution by the last follow-up day on January 31, 2023. The effectiveness was evaluated by Cox proportional hazards models based on propensity score analyses. The secondary outcomes were the resolution of cough and other COVID-19-related symptoms by Days 3, 5, and 7. RESULTS: Of 1434 patients, 671 patients were excluded from the analysis of cough resolution. Among the remaining 763 patients, 481 (63.04%) received kumquat decoction, and 282 (36.96%) received usual care. The median age was 38.0 (interquartile range [IQR] 29.0, 50.0) years, and 55.7% were women. During a median follow-up of 7.000 days, 68.2% of patients in the kumquat group achieved sustained cough resolution (93.77 per 1000 person-days) compared to 39.7% in the usual care group (72.94 per 1000 person-days). The differences in restricted mean survival time (RMST) (kumquat decoction minus usual care group) for cough resolution were -0.742 days (95% CI, -1.235 to -0.250, P = 0.003) on Day 7. In the main analysis using propensity-score matching, the adjusted hazard ratio (HR) for cough resolution (kumquat decoction vs. usual care group) was 1.94 (95% CI, 1.48 to 2.53, P < 0.001). Similar findings were found in multiple sensitivity analyses. In addition, the use of kumquat decoction was associated with the resolution of cough, and a stuffy nose on Days 5 and 7, as well as the resolution of sore throat on Day 7 following medication. CONCLUSION: In this study among patients with COVID-19-related cough, receiving kumquat decoction was associated with an earlier resolution of cough symptoms.

Effect of bifenthrin application at different maturity stages on its dissipation and residues in kumquat (Citrus japonica) and dietary intake risk assessment.

Bifenthrin is a pyrethroid pesticide widely used on kumquats, but the residues in the peel and pulp after bifenthrin application at different maturity stages of kumquats have not been evaluated. This study developed a simple and rapid high-performance liquid chromatography (HPLC) method for the quantitative analysis of bifenthrin residues in whole fruit, kumquat peel, kumquat pulp, and soil. The results showed that regardless of whether bifenthrin was applied one or three times during the near-mature period, the half-lives of the fruit peel and fruit pulp were longer than those in the immature period. Kumquat fruit residues decreased with time at both maturity levels. The residues of bifenthrin in near-mature fruit exceeded the MRL in Guangxi and Fujian 14 days after the three applications of bifenthrin, suggesting that this issue should be focused on in kumquat production and supervision. However, for bifenthrin application in either the near-mature or the immature fruit period, the calculated risks for chronic dietary intake of kumquat were well below 100%. The data demonstrate that the chronic dietary intake risk of bifenthrin through kumquat consumption is low and within acceptable limits. These results provide a reference and risk assessment data for the safe and rational use of bifenthrin insecticides.

Functional Characterization of a Flavone Synthase That Participates in a Kumquat Flavone Metabolon.

Flavones predominantly accumulate as O- and C-glycosides in kumquat plants. Two catalytic mechanisms of flavone synthase II (FNSII) support the biosynthesis of glycosyl flavones, one involving flavanone 2-hydroxylase (which generates 2-hydroxyflavanones for C-glycosylation) and another involving the direct catalysis of flavanones to flavones for O-glycosylation. However, FNSII has not yet been characterized in kumquats. In this study, we identified two kumquat FNSII genes (FcFNSII-1 and FcFNSII-2), based on transcriptome and bioinformatics analysis. Data from in vivo and in vitro assays showed that FcFNSII-2 directly synthesized apigenin and acacetin from naringenin and isosakuranetin, respectively, whereas FcFNSII-1 showed no detectable catalytic activities with flavanones. In agreement, transient overexpression of FcFNSII-2 in kumquat peels significantly enhanced the transcription of structural genes of the flavonoid-biosynthesis pathway and the accumulation of several O-glycosyl flavones. Moreover, studying the subcellular localizations of FcFNSII-1 and FcFNSII-2 demonstrated that N-terminal membrane-spanning domains were necessary to ensure endoplasmic reticulum localization and anchoring. Protein-protein interaction analyses, using the split-ubiquitin yeast two-hybrid system and bimolecular fluorescence-complementation assays, revealed that FcFNSII-2 interacted with chalcone synthase 1, chalcone synthase 2, and chalcone isomerase-like proteins. The results provide strong evidence that FcFNSII-2 serves as a nucleation site for an O-glycosyl flavone metabolon that channels flavanones for O-glycosyl flavone biosynthesis in kumquat fruits. They have implications for guiding genetic engineering efforts aimed at enhancing the composition of bioactive flavonoids in kumquat fruits.

Effect of Osmotic Dehydration Pretreatment on the Drying Characteristics and Quality Properties of Semi-Dried (Intermediate) Kumquat (Citrus japonica) Slices by Vacuum Dryer.

The effect of osmotic dehydration (OD) pretreatments at different temperatures and immersion times on drying characteristics, total phenolic content (TPC), total antioxidant activity (TAA) (DPPH and CUPRAC methods), and color of kumquat slices dried under vacuum conditions (70 °C-100 mbar) was investigated. The OD pretreatment was performed in a sucrose solution (45 °Bx) at the temperatures of 40 and 50 °C and immersed at times of 30, 60, and 90 min. OD before vacuum drying decreased the total required drying time by up to 70 min compared to the control non-pretreated samples. Page, Modified Page, Henderson Pabis, and Two Terms Exponential models were found to satisfactorily describe the drying behavior of thin layer dried kumquat slices. The minimum and maximum values of effective moisture diffusivity (Deff) for semi-dried kumquat slices were 5.04 × 10-8 to 7.19 × 10-8, respectively. OD treatments induced a decline in TPC (5.30-33.92%) and TAA (23.63-59.34% and 4.17-31.67% for DPPH and CUPRAC assays, respectively) of kumquat slices. It was observed that OD pre-treatment can decrease the gross drying time, and make the color and sensorial attributes of dried kumquats better.

Two Dof transcription factors promote flavonoid synthesis in kumquat fruit by activating C-glucosyltransferase.

Although DNA binding with one finger (Dof) constitutes a crucial plant-specific family of transcription factors (TFs) that plays important roles in a wide range of biological processes, the molecular mechanisms underlying Dof regulation of flavonoid biosynthesis in plants remain largely unknown. Here, we characterized 28 Dof genes (FhDof1-FhDof28) from the 'Hongkong' kumquat (Fortunella hindsii) cultivar genome. Promoter analysis and transcriptome profiling revealed that four FhDofs - FhDof4, FhDof9, FhDof15, and FhDof16 - may be involved in flavonoid biosynthesis through binding to the flavonoid C-glycosyltransferase (FhCGT) promoter. We cloned homologous genes of four FhDofs, designated as FcDof4, FcDof9, FcDof15, FcDof16, and a homologous gene of FhCGT, designated as FcCGT, from the widely cultivated 'HuaPi' kumquat (F. crassifolia). Quantitative reverse transcription-polymerase chain reaction analysis revealed that FcDof4 and FcDof16 were significantly correlated with FcCGT expression during development stages in the 'HuaPi' fruit (Pearson's correlation coefficient > 0.7) and were localized to the nucleus. Results of yeast one-hybrid, electrophoretic mobility shift, and dual-luciferase assays indicated that the two FcDofs trigger FcCGT expression by specifically binding to its promoters. Moreover, transient overexpression of FcDof4 and FcDof16 enhances the transcription of structural genes in the flavonoid biosynthetic pathway and increases C-glycosylflavonoid content. Our results provide strong evidence that the TFs FcDof4 and FcDof16 promote flavonoid synthesis in kumquat fruit by activating FcCGT expression.

Drying kinetics and physicochemical properties of kumquat under hot air and air-impingement jet dryings.

Kumquat is famous for its unique flavor and nutritional value. In this study, the drying kinetics, moisture effective diffusivity, phytochemical properties, and antioxidant capacities of kumquat dried by hot air drying (HAD) and air-impingement jet drying (AIJD) were comparatively investigated. The results showed that drying rate, moisture effective diffusivity, and nutrient retention under AIJD were better than those under HAD. Fourteen polyphenols were identified by UPLC-QqQ-MS/MS in kumquat slices. The content of limonoid was significantly increased after AIJD. It was also found that high temperature contributed to a higher drying rate. However, most of the polyphenol components decreased at high drying temperatures. Accordingly, AIJD 60 °C was regarded as the optimum condition for kumquat drying. This work contributed to a better understanding of the drying character of kumquat under AIJD and showed the bioactive compounds and antioxidant activities are affected by drying methods.

Metabolic Profiling and Gene Expression Analysis Unveil Differences in Flavonoid and Lipid Metabolisms Between 'Huapi' Kumquat (Fortunella crassifolia Swingle) and Its Wild Type.

To elucidate the mechanism underlying special characteristic differences between a spontaneous seedling mutant 'Huapi' kumquat (HP) and its wild-type 'Rongan' kumquat (RA), the fruit quality, metabolic profiles, and gene expressions of the peel and flesh were comprehensively analyzed. Compared with RA, HP fruit has distinctive phenotypes such as glossy peel, light color, and few amounts of oil glands. Interestingly, HP also accumulated higher flavonoid (approximately 4.1-fold changes) than RA. Based on metabolomics analysis, we identified 201 differential compounds, including 65 flavonoids and 37 lipids. Most of the differential flavonoids were glycosylated by hexoside and accumulated higher contents in the peel but lower in the flesh of HP than those of RA fruit. For differential lipids, most of them belonged to lysophosphatidycholines (LysoPCs) and lysophosphatidylethanolamines (LysoPEs) and exhibited low abundance in both peel and flesh of HP fruit. In addition, structural genes associated with the flavonoid and lipid pathways were differentially regulated between the two kumquat varieties. Gene expression analysis also revealed the significant roles of UDP-glycosyltransferase (UGT) and phospholipase genes in flavonoid and glycerophospholipid metabolisms, respectively. These findings provide valuable information for interpreting the mutation mechanism of HP kumquat.

Effect of chitosan-based coatings enriched with savory and/or tarragon essential oils on postharvest maintenance of kumquat (Fortunella sp.) fruit.

The present study assessed the ability of chitosan-based coatings incorporating savory and/or tarragon essential oils (EOs) to preserve the postharvest quality of kumquats. Changes in weight loss, titratable acidity, total soluble solids, and vitamin C content were determined over 30 days of storage at 7°C. Savory (Satureja hortensias L.) essential oil was characterized by thymol (29.1%), carvacrol (26.6%), and γ-terpinene (24.72%) as major constituents. While, in the tarragon (Artemisia dracunculus L.) essential oil, estragol (81.89%), ß-cis-Ocimene (4.62%), and ß-trans-Ocimene (3.44%) were the main ones. The CH-EOs coatings were effective in reducing weight loss of kumquats fruits during storage. Moreover, the tested composite coatings showed positive effects in maintaining vitamin C and fruits treated with CH-oil coatings retained good sensory acceptability. The obtained results demonstrate the potential of the combined application of chitosan and savory and/or tarragon EOs as a promising postharvest treatment for maintaining the postharvest quality of kumquats fruits.