Two telomere-to-telomere gapless genomes reveal insights into Capsicum evolution and capsaicinoid biosynthesis.

Chili pepper (Capsicum) is known for its unique fruit pungency due to the presence of capsaicinoids. The evolutionary history of capsaicinoid biosynthesis and the mechanism of their tissue specificity remain obscure due to the lack of high-quality Capsicum genomes. Here, we report two telomere-to-telomere (T2T) gap-free genomes of C. annuum and its wild nonpungent relative C. rhomboideum to investigate the evolution of fruit pungency in chili peppers. We precisely delineate Capsicum centromeres, which lack high-copy tandem repeats but are extensively invaded by CRM retrotransposons. Through phylogenomic analyses, we estimate the evolutionary timing of capsaicinoid biosynthesis. We reveal disrupted coding and regulatory regions of key biosynthesis genes in nonpungent species. We also find conserved placenta-specific accessible chromatin regions, which likely allow for tissue-specific biosynthetic gene coregulation and capsaicinoid accumulation. These T2T genomic resources will accelerate chili pepper genetic improvement and help to understand Capsicum genome evolution.

Prevalence and risk factors for isolated systolic hypertension among the oldest-old population in southwestern China: A community-based cross-sectional study.

The prevalence of isolated systolic hypertension (ISH) has doubled between 2002-2005 and 2014 among the oldest-old population in China. However, the prevalence and characteristics of ISH among the oldest-old population in southwestern China remain less known. This study aimed to investigate the prevalence of ISH among the oldest-old population in Chengdu and identify associated factors to provide valuable information for disease etiology and prevention. We recruited 1,312 participants aged over 80 years by using a stratified cluster sampling method between September 2015 and June 2016, from three districts (Jinjiang, Qingyang, and Longquanyi) of Chengdu, the largest city of southwest China. A structured questionnaire, anthropometric data, and blood pressure were collected according to the standard method. Blood pressure was measured three times by using a standardized mercury sphygmomanometer after a 10-minute seated rest. Of 1312 participants, 53.0% (n = 695) had ISH. The prevalence of ISH in men and women was 54.7% and 51.3%, respectively, with no significant sex difference (P = .222). The prevalence of ISH increased with advanced age in men (P for trend = 0.029), 52.5% for the 80-84 years group, 55.2% for the 85-89 years group, and 70.4% for the 90-98 years group, respectively. Multivariable logistic regression analyses found that drinking (OR = 1.85, 95%CI = 1.26-2.71), being overweight (OR = 1.88, 95%CI = 1.19-2.96), and having a higher heart rate (OR = 0.66, 95%CI = 0.51-0.86) were associated with ISH. Stratified by sex, these three factors remained significant in men. Our work highlights that the burden of ISH is substantial among the oldest-old population in southwestern China.

Repressing miR-23a promotes the transdifferentiation of pancreatic α cells to ß cells via negatively regulating the expression of SDF-1α.

Pancreatic ß-cell failure is a pathological feature in type 1 diabetes. One promising approach involves inducing transdifferentiation of related pancreatic cell types, specifically α cells that produce glucagon. The chemokine stromal cell-derived factor-1 alpha (SDF-1α) is implicated in pancreatic α-to-ß like cell transition. Here, the serum level of SDF-1α was lower in T1D with C-peptide loss, the miR-23a was negatively correlated with SDF-1α. We discovered that exosomal miR-23a, secreted from ß cells, functionally downregulates the expression of SDF-1α, leading to increased Pax4 expression and decreased Arx expression in vivo. Adenovirus-vectored miR-23a sponge and mimic were constructed to further explored the miR-23a on pancreatic α-to-ß like cell transition in vitro, which yielded results consistent with our cell-based assays. Suppression of miR-23a upregulated insulin level and downregulated glucagon level in STZ-induced diabetes mice models, effectively promoting α-to-ß like cell transition. Our findings highlight miR-23a as a new therapeutic target for regenerating pancreatic ß cells from α cells.

Fine mapping of ClLOX, a QTL for powdery mildew resistance in watermelon (Citrullus lanatus L.).

KEY MESSAGE: ClLOX, is located on chromosome 2 and encodes a lipoxygenase gene, which induced watermelon powdery mildew resistance by inhibiting pathogen spread. Powdery mildew is one of the most severe fungal diseases reducing yield and quality of watermelon (Citrullus lanatus L.) and other cucurbit crops. Genes responsible for powdery mildew resistance in watermelon are highly valuable. In this study, we first identified the QTL pm-lox for powdery mildew resistance in watermelon, located within a 0.93 Mb interval of chromosome 2, via XP-GWAS method using two F2 populations. The F2:3 families from one of the F2 populations were then used for fine-mapping the pm-lox locus into a 9,883 bp physical region between 29,581,906 and 29,591,789, containing only two annotated genes. Of these, only ClG42_02g0161300 showed a significant differential expression between the resistant and susceptible lines after powdery mildew inoculation based on RNA sequencing (RNA-seq) and qRT-PCR analysis, and is designated ClLOX. Derived Cleaved Amplified Polymorphic Sequence (dCAPs) markers were developed and validated. In addition, our tests showed that the resistance was anti-spread rather than anti-infection of the pathogen. This study identified a new resistance gene (ClLOX), provided insights into the mechanism of powdery mildew resistance, and developed a molecular marker for watermelon breeding.

Exploring non-invasive precision treatment in non-small cell lung cancer patients through deep learning radiomics across imaging features and molecular phenotypes.

BACKGROUND: Accurate prediction of tumor molecular alterations is vital for optimizing cancer treatment. Traditional tissue-based approaches encounter limitations due to invasiveness, heterogeneity, and molecular dynamic changes. We aim to develop and validate a deep learning radiomics framework to obtain imaging features that reflect various molecular changes, aiding first-line treatment decisions for cancer patients. METHODS: We conducted a retrospective study involving 508 NSCLC patients from three institutions, incorporating CT images and clinicopathologic data. Two radiomic scores and a deep network feature were constructed on three data sources in the 3D tumor region. Using these features, we developed and validated the 'Deep-RadScore,' a deep learning radiomics model to predict prognostic factors, gene mutations, and immune molecule expression levels. FINDINGS: The Deep-RadScore exhibits strong discrimination for tumor molecular features. In the independent test cohort, it achieved impressive AUCs: 0.889 for lymphovascular invasion, 0.903 for pleural invasion, 0.894 for T staging; 0.884 for EGFR and ALK, 0.896 for KRAS and PIK3CA, 0.889 for TP53, 0.895 for ROS1; and 0.893 for PD-1/PD-L1. Fusing features yielded optimal predictive power, surpassing any single imaging feature. Correlation and interpretability analyses confirmed the effectiveness of customized deep network features in capturing additional imaging phenotypes beyond known radiomic features. INTERPRETATION: This proof-of-concept framework demonstrates that new biomarkers across imaging features and molecular phenotypes can be provided by fusing radiomic features and deep network features from multiple data sources. This holds the potential to offer valuable insights for radiological phenotyping in characterizing diverse tumor molecular alterations, thereby advancing the pursuit of non-invasive personalized treatment for NSCLC patients.

Non-invasive decision support for clinical treatment of non-small cell lung cancer using a multiscale radiomics approach.

BACKGROUND: Selecting therapeutic strategies for cancer patients is typically based on key target-molecule biomarkers that play an important role in cancer onset, progression, and prognosis. Thus, there is a pressing need for novel biomarkers that can be utilized longitudinally to guide treatment selection. METHODS: Using data from 508 non-small cell lung cancer (NSCLC) patients across three institutions, we developed and validated a comprehensive predictive biomarker that distinguishes six genotypes and infiltrative immune phenotypes. These features were analyzed to establish the association between radiological phenotypes and tumor genotypes/immune phenotypes and to create a radiological interpretation of molecular features. In addition, we assessed the sensitivity of the models by evaluating their performance at five different voxel intervals, resulting in improved generalizability of the proposed approach. FINDINGS: The radiomics model we developed, which integrates clinical factors and multi-regional features, outperformed the conventional model that only uses clinical and intratumoral features. Our combined model showed significant performance for EGFR, KRAS, ALK, TP53, PIK3CA, and ROS1 mutation status with AUCs of 0.866, 0.874, 0.902, 0.850, 0.860, and 0.900, respectively. Additionally, the predictive performance for PD-1/PD-L1 was 0.852. Although the performance of all models decreased to different degrees at five different voxel space resolutions, the performance advantage of the combined model did not change. CONCLUSIONS: We validated multiscale radiomic signatures across tumor genotypes and immunophenotypes in a multi-institutional cohort. This imaging-based biomarker offers a non-invasive approach to select patients with NSCLC who are sensitive to targeted therapies or immunotherapy, which is promising for developing personalized treatment strategies during therapy.

Atypical cutaneous presentation of AOSD with persistent itchy urticaria: A case report.

RATIONALE: Adult-onset Still's disease (AOSD) is a rare multisystem disorder considered a complex autoinflammatory syndrome. The clinical and biological features of AOSD typically include a high fever with arthritic symptoms, evanescent skin rash, sore throat, striking neutrophilic leukocytosis, hyperferritinemia, and abnormal liver function. The typical rash and fever are important diagnostic clues for AOSD. Here, we report a case of atypical rash manifesting as persistent itchy urticaria. PATIENT CONCERNS: A 57-year-old female presented with a 6-day history of fever. During her hospital stay, she progressively developed rashes that were not associated with fever, primarily distributed on her back and the distal extremities, and associated with pronounced itching. The rash was initially suspected to be urticaria; however, the patient exhibited a poor response to antihistamines. After malignancies and other rheumatic diseases were excluded, the diagnosis leaned towards AOSD based on diagnostic criteria. The patient's fever was well controlled with the initiation of glucocorticoids, and no further rashes were observed. DIAGNOSES: Although the patient exhibited atypical rashes, after ruling out malignancies and other rheumatic diseases, she met 2 major and 3 minor criteria. Based on Yamaguchi's criteria, the patient was diagnosed with AOSD. INTERVENTIONS: Initially, the patient was administered an intravenous infusion of methylprednisolone at 40 mg once daily. This was later transitioned to oral administration with gradual dose reduction. OUTCOMES: Follow-up at 1 year showed no recurrence of the rash, with a stable condition and no relapse. LESSONS: This case provides valuable insights for the early diagnosis of AOSD, emphasizing the importance of considering this diagnosis even when presenting with atypical skin rash.

Cobalt(II)-Catalyzed Enantioselective Propargyl Claisen Rearrangement: Access to Allenyl-Substituted Quaternary ß-Ketoesters.

Highly enantioselective propargyl Claisen rearrangement of O-propargyl ß-ketoesters was achieved under 2.5 mol % of the chiral cobalt complex as the catalyst under mild reaction conditions. With Co(OTf)2 as the Lewis acid and C1-symmetric imidazoline-pyrroloimidazolone pyridine as the ligand, diverse chiral allenyl-substituted all-carbon quaternary ß-ketoesters were obtained in good yields (up to 97% yield) and high enantioselectivities (up to 98% ee).

Establishment of insomnia model of chronic unpredictable stress in rats.

It is well known that stressful situation is one of the important factors causing insomnia, however, the underlying mechanism is still elusive. Therefore, the establishment of a suitable animal model of stress insomnia will be of great help to solve this problem. In this study, by combining with chronic unpredictable stress (multitude of stressors) and sleep deprivation, we attempted to establish a rat model of stress insomnia. It was observed that rats with stress insomnia showed significant weight loss, and less sleep quality in pentobarbital sodium induced sleep test and electroencephalogram detection. Moreover, rats with stress insomnia showed greater depression and anxiety detected by forced swimming, sucrose preference test and open field. Since oxidative stress has been reported to be involved in insomnia, we further evaluated the production of oxidative stress and found that the levels of lipid peroxidation product malondialdehyde (MDA) in liver, serum total bilirubin and urine biopyrrin were all significantly increased in rats with stress insomnia. In addition, we also found that the memory of these rats with stress insomnia was also obviously reduced in water maze. Taken together, these results demonstrate that the emotional behaviors, memory, oxidative and metabolism of the rats were all significantly changed after modeling, indicating a rat model of stress insomnia was successful establishment, and this animal model will provide basis to further explore the underlying mechanism of chronic stress in insomnia.

Radiomics under 2D regions, 3D regions, and peritumoral regions reveal tumor heterogeneity in non-small cell lung cancer: a multicenter study.

PURPOSE: Lung cancer has significant genetic and phenotypic heterogeneity, leading to poor prognosis. Radiomic features have emerged as promising predictors of the tumor phenotype. However, the role of underlying information surrounding the cancer remains unclear. MATERIALS AND METHODS: We conducted a retrospective study of 508 patients with NSCLC from three institutions. Radiomics models were built using features from six tumor regions and seven classifiers to predict three prognostically significant tumor phenotypes. The models were evaluated and interpreted by the mean area under the receiver operating characteristic curve (AUC) under nested cross-validation and Shapley values. The best-performing predictive models corresponding to six tumor regions and three tumor phenotypes were identified for further comparative analysis. In addition, we designed five experiments with different voxel spacing to assess the sensitivity of the experimental results to the spatial resolution of the voxels. RESULTS: Our results demonstrated that models based on 2D, 3D, and peritumoral region features yielded mean AUCs and 95% confidence intervals of 0.759 and [0.747-0.771] for lymphovascular invasion, 0.889 and [0.882-0.896] for pleural invasion, and 0.839 and [0.829-0.849] for T-staging in the testing cohort, which was significantly higher than all other models. Similar results were obtained for the model combining the three regional features at five voxel spacings. CONCLUSION: Our study revealed the predictive role of the developed methods with multi-regional features for the preoperative assessment of prognostic factors in NSCLC. The analysis of different voxel spacing and model interpretability strengthens the experimental findings and contributes to understanding the biological significance of the radiological phenotype.

Business model and supporting policies for projects to implement carbon capture and power-to-gas technologies.

The project portfolio of carbon capture system and power to gas (CP project) is considered to be a key technology combination for achieving carbon emission reduction and recycling in the future. However, due to a dearth of associated engineering practices and business activities, there is no widely used business model for the large-scale deployment of the CP technology portfolio. The design and evaluation of the business model is crucial for projects with a long industrial chain and complex relationships between stakeholders, such as CP projects. Based on carbon chain and energy flow, this paper analyzes the cooperation mode and profitability among stakeholders in the CP industry chain, selects three suitable business models, and establishes nonlinear optimization models under the three business models. By analyzing the key factors (e.g. carbon price) that can promote investment and have policy influence, the tipping points of the key factors and the cost of support policies are given. Results show that the vertical integration model has the greatest demonstration deployment potential since it has the best performance in terms of cooperation and profitability realization. However, required crucial factors in the CP projects vary from business models, policy makers need to take appropriate supporting measures prudently.

Establishment of a chronic insomnia rat model of sleep fragmentation using unstable platforms surrounded by water.

Chronic fragmented sleep is a very common type of insomnia that affects the daily lives of numerous people around the world. However, its pathogenesis is not very clear and a corresponding rat model has not been reported for this purpose at present. The present study aimed to establish a rat model of chronic insomnia with sleep fragmentation using self-made multiple strings of unstable platforms surrounded by shallow water. During the establishment of the models, changes in body weight and differences in food and water intake in the daytime and at night were acquired. The rat models were assessed using several tests, including the Morris water maze test, pentobarbital sodium-induced sleep, infrared monitoring and electroencephalogram/electromyography during sleep. The expression levels of certain inflammatory factors and orexin A were detected in the serum and brain tissues using ELISAs, immunohistochemistry and immunofluorescence. The expression levels of orexin 1 receptor (orexin 1r) were also detected in the brain. Polysomnography indicated that the model rats were successfully prepared with reduced non-rapid eye movement (non-REM) sleep in the daytime, which was increased at night, and considerably lower REM duration during the day and night. The number of instances of sleep arousals were also increased in the day and at night, and the average duration of each sleep bout was decreased in the daytime. The body weights of the model rats increased at a normal rate. However, the reduction of body weight in the daytime and increased in body weight at night were significantly less than those of the control rats. The daytime food and water consumption of the model rats increased significantly compared with that of the control rats, but was similar to that of the control group at night. The Morris water maze test indicated that the model rats were slow to learn to escape the platforms and performed a lower number of target crossings. The pentobarbital-induced sleep experiment confirmed that the model rats exhibited a longer sleep latency and shorter sleep time. The serum IL-1ß, IL-6, TNF-α and orexin A levels of the model rats were significantly increased, whereas their serum IL-10 levels were significantly decreased compared with those of the control rats. The expression levels of IL-1ß, IL-6, orexin A and orexin 1r in the brain tissues of the model rats were also significantly increased. In conclusion, these data indicate that learning and memory function, sleep time, arousal times, diurnal and nocturnal body weight changes, food and water intake, and expression levels of the specific inflammatory factors orexin A and orexin 1r were altered in the model rats. This suggests the chronic insomnia rat model with sleep fragmentation was successfully established using multiple strings of unstable platforms surrounded by water.

Successful neoadjuvant treatment of EGFR exon 19 deletion combined with TP53 mutation in non-small cell lung cancer using aumolertinib after osimertinib-induced myocardial damage: a case report and literature review.

The development of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) represents a paradigm shift in the treatment of lung cancer with EGFR mutations. Aumolertinib has been shown to be a safe agent in the registry study. However, successful rechallenge with aumolertinib following osimertinib-induced myocardial damage has not been reported. In this article, a case of neoadjuvant therapy for lung adenocarcinoma is retrospectively analyzed, and the relevant literature is reviewed. The patient was diagnosed with stage IIIA lung adenocarcinoma, and genetic testing revealed EGFR exon 19 deletion mutation combined with Tumor Protein p53 (TP53) mutation. The mutation abundance is 33.5 and 14%, respectively. One month after osimertinib treatment, the patient developed myocardial damage, and abnormal indicators such as myocardial enzyme spectrum showed abnormalities and cardiac insufficiency, followed by pulmonary hypertension and pulmonary edema. Aumolertinib was subsequently used for treatment, following which the myocardial enzyme spectrum returned to normal, and the symptoms of bilateral interstitial edema disappeared. In addition to the disappearance of adverse reactions, the therapeutic effect was excellent; the lung lesions and mediastinal lymph nodes were significantly reduced, and the operation was successfully conducted. This is the first report of successful neoadjuvant treatment of EGFR exon 19 deletion combined with TP53 mutation in NSCLC using aumolertinib after osimertinib-induced myocardial damage. The results suggested that aumolertinib had fewer adverse reactions in patients with EGFR exon 19 deletion combined with TP53 mutation, and aumolertinib may be a potential neoadjuvant therapy for stage IIIA lung cancer.

Kidney Mesenchymal stem cells alleviate cisplatin-induced kidney injury and apoptosis in rats.

OBJECTIVE: This experiment was designed to demonstrate Mesenchymal stem cells (MSCs) derived from kidney can alleviate cisplatin-induced kidney injury and renal cell apoptosis through paracrine pathway. METHODS: Firstly, MSCs were isolated from kidney of young rats, and their surface-specific markers were identified by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and immunofluorescence staining. Self-renewal ability of Kidney Mesenchymal Stem Cells (KMSCs) was observed by cell counting and 5-Bromo-2'-deoxyuridine (BrdU) fluorescence staining. KMSCs at logarithmic growth stage were traced and injected into rat through tail vein. RESULTS: The results showed that KMSCs homed in the kidney tissues, decreased the secretion of inflammatory factors (CRP, TNFα, IL-1ß, IL-6), and alleviated renal function. Hematoxylin and Eosin (H＆E), Masson and Periodic Acid-silver Methenamine (PASM) staining showed that KMSCs could alleviate pathological damage in rats. Terminal Deoxynucleotidyl Transferase mediated dUTP Nick-End Labeling (TUNEL) assay showed that KMSCs could reduce the apoptosis of rat kidney cells induced by cisplatin. Finally, Immunohistochemistry (IHC) results showed that cisplatin could induce higher expression of the pro-apoptotic protein Bax and lower expression of anti-apoptotic Bcl-2 in kidney tissues. However, KMSCs could reverse the pro-apoptotic effect of cisplatin on kidney cells and improve the survival rate of rats. CONCLUSIONS: In conclusion, KMSCs were successfully isolated from kidney tissues, and KMSCs have therapeutic effects on rat kidney injury induced by cisplatin.

Cu-Catalyzed N-Arylation of Prolinamides: Access to Enantioenriched DMAP Analogues and Its Application in Black Rearrangement.

A CuI-catalyzed C-N coupling reaction of 3-bromo-DMAP with l-prolinamides was conducted at 80 °C in 12-16 h, where the prolinamide's structure had an accelerating effect on the Ullmann-type reaction. This reaction was used to construct chiral 3-amino DMAP catalysts. Furthermore, enantioenriched DMAP analogue C8 was applied in an asymmetric Black rearrangement of 2-benzofuranylcarbonates, affording 3,3-disubstituted benzofuran-2-ones in up to 96% yield and 97% ee.

MnO2 nanosheets-triggered oxVB1 fluorescence immunoassay for detection zearalenone.

In this study, an alkaline phosphatase (ALP)-mediated fluorescence immunoassay for detecting zearalenone (ZEN) was established based on the oxVB1 fluorescence signal modulated by MnO2 nanosheets (MnO2 NS). As the ALP-antibody content increased, more 2-phosphoascorbic acid (AAP) was hydrolyzed to ascorbic acid (AA) which destroyed the MnO2 NS rapidly. In the lack of MnO2 NS, VB1 cannot be oxidized to oxVB1 for emitting fluorescence. On the contrary, the fluorescence of oxVB1 recovered slowly with the decrease of the ALP-antibody concentration. In the optimization condition, the detection limit of this method was 15.5 pg mL-1. Moreover, the recovery of ZEN in real samples ranged from 94.24 % to 108.26 %, which indicated the remarkable accuracy and reliability of this approach. Meanwhile, the proposal of this fluorescence immunoassay provided a new possibility for detecting other targets by replacing antibodies and antigens.

Fluorescence and colorimetric dual-mode immunoassay based on G-quadruplex/N-methylmesoporphyrin IX and p-nitrophenol for detection of zearalenone.

In this work, a fluorescence and colorimetric dual-mode immunoassay for detecting zearalenone (ZEN) was established. This platform relied on the dephosphorylation of p-nitrophenyl phosphate (PNPP) by alkaline phosphatase (ALP) to produce yellow p-nitrophenol (PNP). And the internal filtration effect between G-quadruplex/N-methylmesoporphyrin IX (G4/NMM) and PNP led to fluorescence quenching of G4/NMM. Therefore, the color change of PNP and the fluorescence change of G4/NMM can be used as double signals to report the results of ALP mediated immunoassay. In this dual-mode immunoassay, the detection limit of fluorescence mode was 0.0072 ng/mL with a linear range 7.5-17.5 ng/mL. And the detection limit of colorimetric mode was 0.036 ng/mL with a linear range 7.5-20 ng/mL. In addition, the dual-mode immunoassay showed good selectivity for ZEN and satisfactory recovery in corn samples (fluorescence mode: 94.40-106.80%, colorimetric mode: 96.51-108.27%).

Multi-objective optimization of coal-fired power units considering deep peaking regulation in China.

China states to build new power system dominated by new energy power to promote the targets for peaking carbon emissions by 2030 and achieve carbon neutrality by 2060. Peaking regulation ancillary services provided by coal-fired power units is an essential solution to mitigate the volatility and instability of large-scale renewable energy for China's specific power mix. However, when the coal-fired power units operate at a low power output, the intensity of both coal consumption and carbon emissions gradually rises with the falling output rate. Moreover, cutting down the power output of coal-fired units frequently will damage the technical life. Given the impacts of power market reform and carbon mitigation targets, whether to participate in the energy market or the peaking regulation ancillary service market is an urgent issue for coal-fired power units. Considering the discrepancy in costs and benefits of various units at different output rate, this paper proposes a multi-objective optimization model to solve the issue from the perspective of the coal-fired power generators, in which both economic profit and carbon reduction goals are coordinated. Sequential quadratic programming is adopted to solve the nonlinear optimization problem. In order to study the difference in the decisions made by varied technical units, 7 different types of units are analyzed in the case study. The scenarios analysis indicates that large-capacity and new coal-fired power units are better to participate in energy market since it can give full play to the advantage of higher generation efficiency, while the small-capacity ones are suitable to provide flexible service in the peaking regulation ancillary service market. Besides, simple low-carbon objective will burden the cost of coal-fired power units and challenge the sustainable transition of power system. Hence, the power system should balance both economic profit of generators and national carbon mitigation targets during the low-carbon transition.

Watermelon domestication was shaped by stepwise selection and regulation of the metabolome.

Although crop domestication has greatly aided human civilization, the sequential domestication and regulation of most quality traits remain poorly understood. Here, we report the stepwise selection and regulation of major fruit quality traits that occurred during watermelon evolution. The levels of fruit cucurbitacins and flavonoids were negatively selected during speciation, whereas sugar and carotenoid contents were positively selected during domestication. Interestingly, fruit malic acid and citric acid showed the opposite selection trends during the improvement. We identified a novel gene cluster (CGC1, cucurbitacin gene cluster on chromosome 1) containing both regulatory and structural genes involved in cucurbitacin biosynthesis, which revealed a cascade of transcriptional regulation operating mechanisms. In the CGC1, an allele caused a single nucleotide change in ClERF1 binding sites (GCC-box) in the promoter of ClBh1, which resulted in reduced expression of ClBh1 and inhibition of cucurbitacin synthesis in cultivated watermelon. Functional analysis revealed that a rare insertion of 244 amino acids, which arose in C. amarus and became fixed in sweet watermelon, in ClOSC (oxidosqualene cyclase) was critical for the negative selection of cucurbitacins during watermelon evolution. This research provides an important resource for metabolomics-assisted breeding in watermelon and for exploring metabolic pathway regulation mechanisms.