Phenomics and transcriptomic profiling of fruit development in distinct apple varieties.

Apple is one of the most economically important and popular temperate fruit trees. The domestication of apple has resulted in substantial phenotypic differences, particularly between wild and cultivated varieties. However, the relationship between gene expression and phenotypic variations in apple remains poorly understood. Here, we present a comprehensive dataset featuring five distinct apple varieties, including two wild varieties and three representative cultivated varieties. The dataset comprises of both phenomics data, encompassing twelve fruit quality-related traits continuously measured over two years, and transcriptomic data obtained at different developmental stages with three biological replicates. We performed basic quality control process, gene expression normalization and differential gene expression analysis to demonstrate the utility and reliability of the dataset. Our findings indicate that gene expression strongly related with phenotypic variations in apple. This dataset serves as a valuable resource, encompassing phenomics and transcriptomic data in multiple formats, thereby facilitating further exploration of the relationships between gene expression and phenotypic traits in apple.

Two adjacent NAC transcription factors regulate fruit maturity date and flavor in peach.

Although maturity date (MD) is an essential factor affecting fresh fruit marketing and has a pleiotropic effect on fruit taste qualities, the underlying mechanisms remain largely unclear. In this study, we functionally characterized two adjacent NAM-ATAF1/2-CUC2 (NAC) transcription factors (TFs), PpNAC1 and PpNAC5, both of which were associated with fruit MD in peach. PpNAC1 and PpNAC5 were found capable of activating transcription of genes associated with cell elongation, cell wall degradation and ethylene biosynthesis, suggesting their regulatory roles in fruit enlargement and ripening. Furthermore, PpNAC1 and PpNAC5 had pleiotropic effects on fruit taste due to their ability to activate transcription of genes for sugar accumulation and organic acid degradation. Interestingly, both PpNAC1 and PpNAC5 orthologues were found in fruit-producing angiosperms and adjacently arranged in all 91 tested dicots but absent in fruitless gymnosperms, suggesting their important roles in fruit development. Our results provide insight into the regulatory roles of NAC TFs in MD and fruit taste.

How China's Great Bay Area Policies Affect the National Identity of Hong Kong Youth-A Study of a Quasi-Natural Experiment Based on the Difference-in-Differences Model.

China's Bay Area policies are important for integrating Hong Kong (HK) and Macao youth into China's overall development. However, their effect on national identity is still mostly theoretical, lacking objective and scientific empirical evaluations. From a cultural adaptation perspective, interactions between social groups with different cultural backgrounds can promote cultural and political identity transformation. Therefore, guided by China's Bay Area policies, which encourage various cross-border exchanges via economic cooperation, HK youth can keep in touch with such Mainland Chinese cultural values as "responsible government", facilitating "political socialization", and political-cultural adaptation, helping to promote their psychological inclusion into society, contributing to a positive attitude towards the mainland government, and achieving the policy effect of building national identity. A quasi-natural experiment based on the regional differences in the first stages of China's Bay Area policies can help to evaluate their effects on HK youth's national identity. This study defines the initial stage of the Bay Area policy implementation as from 2016, when the 13th Five-Year Plan advocated building the "Great Bay Area of Guangdong, Hong Kong and Macao", to 2019, when the Outline was published. The policies issued at this stage were the so-called "early policies". Due to data limitations, it is difficult to obtain post-2019 survey data; therefore, the study mainly focuses on the policy effects at the beginning of the Bay Area's construction. Four groups of cross-sectional data from the World Value Survey 6 (WVS6) (2010-2014) and World Value Survey 7 (WVS7) (2017-2020), with HK and the mainland (the non-Guangdong region) included, are used to examine the policy effect under the Difference-in-Differences (DID) Model. The research shows that the policies significantly enhanced HK youth's national identity, and their trust in the mainland government played an intermediary role in the policy effect mechanism. However, the effect was uneven, benefiting the national identities of HK youth working in the for-profit private sector more than their unemployed or public sector peers. Therefore, this research proposes several policy implications to facilitate policy decision making related to youth in China's Bay Area.

NUCKS1 promotes the progression of colorectal cancer via activating PI3K/AKT/mTOR signaling pathway.

Nuclear ubiquitous casein and cyclin-dependent kinase substrate 1 (NUCKS1) is highly expressed in a variety of malignant tumors and functions as an oncogene; however, its role in colorectal cancer (CRC) remains unclear. We aimed to explore the function and regulatory mechanisms of NUCKS1 and potential therapeutic agents targeting NUCKS1 in CRC. We knocked down and overexpressed NUCKS1 in CRC cells and explored its effects in vitro and in vivo. Flow cytometry, CCK-8, Western blotting, colony formation, immunohistochemistry, in vivo tumorigenic, and transmission electron microscopy analyses were performed to determine the effects of NUCKS1 on CRC cell function. LY294002 was used to examine the mechanism of NUCKS1 expression in CRC cells. Potential therapeutic agents for NUCKS1-high CRC patients were analyzed using the CTRP and PRISM datasets, and the function of selected agents was determined by CCK-8 and Western blotting. We revealed that NUCKS1 was highly expressed in CRC tissues and clinically correlated with poor prognosis in CRC patients. NUCKS1 knockdown induces cell cycle arrest, inhibits CRC cell proliferation, and promotes apoptosis and autophagy. These results were reversed when NUCKS1 was overexpressed. Mechanistically, NUCKS1 exerts a cancer-promoting function by activating the PI3K/AKT/mTOR signaling pathway. This was reversed when LY294002 was used to inhibit the PI3K/AKT pathway. Furthermore, we determined that mitoxantrone exhibited high drug sensitivity in NUCKS1-overexpressing CRC cells. This work demonstrated NUCKS1 plays a crucial role in CRC progression via the PI3K/AKT/mTOR signaling pathway. Additionally, mitoxantrone may be a potential therapeutic agent for CRC treatment. Therefore, NUCKS1 represents a promising anti-tumor therapeutic target.

A metabolic perspective of selection for fruit quality related to apple domestication and improvement.

BACKGROUND: Apple is an economically important fruit crop. Changes in metabolism accompanying human-guided evolution can be revealed using a multiomics approach. We perform genome-wide metabolic analysis of apple fruits collected from 292 wild and cultivated accessions representing various consumption types. RESULTS: We find decreased amounts of certain metabolites, including tannins, organic acids, phenolic acids, and flavonoids as the wild accessions transition to cultivated apples, while lysolipids increase in the "Golden Delicious" to "Ralls Janet" pedigree, suggesting better storage. We identify a total of 222,877 significant single-nucleotide polymorphisms that are associated with 2205 apple metabolites. Investigation of a region from 2.84 to 5.01 Mb on chromosome 16 containing co-mapping regions for tannins, organic acids, phenolic acids, and flavonoids indicates the importance of these metabolites for fruit quality and nutrition during breeding. The tannin and acidity-related genes Myb9-like and PH4 are mapped closely to fruit weight locus fw1 from 3.41 to 3.76 Mb on chromosome 15, a region under selection during domestication. Lysophosphatidylethanolamine (LPE) 18:1, which is suppressed by fatty acid desaturase-2 (FAD2), is positively correlated to fruit firmness. We find the fruit weight is negatively correlated with salicylic acid and abscisic acid levels. Further functional assays demonstrate regulation of these hormone levels by NAC-like activated by Apetala3/Pistillata (NAP) and ATP binding cassette G25 (ABCG25), respectively. CONCLUSIONS: This study provides a metabolic perspective for selection on fruit quality during domestication and improvement, which is a valuable resource for investigating mechanisms controlling apple metabolite content and quality.

Effect Mechanism of Extracurricular Tuition and Implications on "Double Reduction" Policy: Extracurricular Tuition Intensity, Psychological Resilience, and Academic Performance.

Since its implementation in July 2021, the "double reduction (the reduction of the excessive academic burden on primary and middle school students, and the over-heated off-campus tutoring)" policy ("the Policy"), which aims to foster a sound environment for extracurricular education, has attracted much social attention. At the preliminary stage where data and cases are insufficient, it is of theoretical and practical significance to evaluate extracurricular tuition and its effect mechanism before the Policy was implemented. This study analyzed the said question based on the data from the China Education Panel Survey between 2014 and 2015 (CEPS2014-2015) by virtue of propensity score matching (PSM) and the intermediate effect. The research found that: (1) extracurricular tuition (ET) is positively correlated with academic performance (AP); (2) high and low extracurricular tuition intensities (ETIs) show no difference in improving academic performance, and the group analysis shows that extracurricular tuition is influenced by the "optimal starting zone (OSZ)"; and (3) psychological resilience (PR) is an intermediate variable of extracurricular tuition, which acts as a "conversion valve". Based on the above findings, the research raised the following suggestions. Firstly, we suggest to emphasize the promotion effect of after-class service on students' academic performance and switch the functions of extracurricular tuition to after-sale service. Then, pay attention to the reverse effect of high extracurricular tuition intensity on students' physical and psychological health and their academic performance. In practice, explore the effective "optimal starting zone" of extracurricular tuition for students. Lastly, cultivate students' psychological resilience by shifting the core of education quality improvement from simple stacking of disciplinary knowledge to psychological health development.

Allelic variation of MdMYB123 controls malic acid content by regulating MdMa1 and MdMa11 expression in apple.

Acidity is a key determinant of fruit organoleptic quality. Here, a candidate gene for fruit acidity, designated MdMYB123, was identified from a comparative transcriptome study of two Ma1Ma1 apple (Malus domestica) varieties, "Qinguan (QG)" and "Honeycrisp (HC)" with different malic acid content. Sequence analysis identified an A→T SNP, which was located in the last exon, resulting in a truncating mutation, designated mdmyb123. This SNP was significantly associated with fruit malic acid content, accounting for 9.5% of the observed phenotypic variation in apple germplasm. Differential MdMYB123- and mdmyb123-mediated regulation of malic acid accumulation was observed in transgenic apple calli, fruits, and plantlets. Two genes, MdMa1 and MdMa11, were up- and down-regulated in transgenic apple plantlets overexpressing MdMYB123 and mdmyb123, respectively. MdMYB123 could directly bind to the promoter of MdMa1 and MdMa11, and induce their expression. In contrast, mdmyb123 could directly bind to the promoters of MdMa1 and MdMa11, but with no transcriptional activation of both genes. In addition, gene expression analysis in 20 different apple genotypes based on SNP locus from "QG" × "HC" hybrid population confirmed a correlation between A/T SNP with expression levels of MdMa1 and MdMa11. Our finding provides valuable functional validation of MdMYB123 and its role in the transcriptional regulation of both MdMa1 and MdMa11, and apple fruit malic acid accumulation.

Epigenetic reprogramming of H3K27me3 and DNA methylation during leaf-to-callus transition in peach.

Plant tissues are capable of developing unorganized cell masses termed calluses in response to the appropriate combination of auxin and cytokinin. Revealing the potential epigenetic mechanisms involved in callus development can improve our understanding of the regeneration process of plant cells, which will be beneficial for overcoming regeneration recalcitrance in peach. In this study, we report on single-base resolution mapping of DNA methylation and reprogramming of the pattern of trimethylation of histone H3 at lysine 27 (H3K27me3) at the genome-wide level during the leaf-to-callus transition in peach. Overall, mCG and mCHH were predominant at the genome-wide level and mCG was predominant in genic regions. H3K27me3 deposition was mainly detected in the gene body and at the TSS site, and GAGA repetitive sequences were prone to recruit H3K27me3 modification. H3K27me3 methylation was negatively correlated with gene expression. In vitro culture of leaf explants was accompanied by DNA hypomethylation and H3K27me3 demethylation, which could activate auxin- and cytokinin-related regulators to induce callus development. The DNA methylation inhibitor 5-azacytidine could significantly increase callus development, while the H3K27me3 demethylase inhibitor GSK-J4 dramatically reduced callus development. These results demonstrate the roles of DNA methylation and H3K27me3 modification in mediating chromatin status during callus development. Our study provides new insights into the epigenetic mechanisms through which differentiated cells acquire proliferative competence to induce callus development in plants.

Children's Filial Piety Changes Life Satisfaction of the Left-Behind Elderly in Rural Areas in China?

Along with the aging of the population and miniaturization of family structure, the problem of the left-behind elderly has become more and more prominent in China. According to the Report on the family development in China (2015) released by the National Health Commission of the People's Republic of China, left-behind elderly people account for half of the total number of the elderly, of whom 10% live alone. The left-behind elderly not only suffer physiological obstacles such as body function decline, but also face a lack of support at the material level and loneliness at the spiritual level, which greatly affects their quality of life, accounting for their lower life satisfaction than that of the ordinary elderly. The rural areas of Sichuan Province are relatively backwards in terms of economic level and have limited pension security. Therefore, the left-behind elderly in rural areas are confronted with more complicated and severe pension problems compared with those in urban areas. Meanwhile, limited by economic and regional factors, a large number of rural labor forces in Sichuan Province have transferred to cities. These long-time migrant workers cannot provide material, spiritual and life care support for their left-behind parents in rural areas in a timely fashion, which changes their filial piety behaviors, and this affects the life satisfaction of the rural left-behind elderly. Therefore, it is necessary to understand the living conditions of empty-nest elderly and their children's filial piety in rural areas of Sichuan province in order to verify the influence mechanism of filial piety on the life satisfaction of the elderly, and to explore how to improve the rural empty-nest elderly's life satisfaction, enabling the elderly to live a healthy and happy life.

Characteristics of Patients with Hematologic Malignancies Without Seroconversion Post-COVID19 Third Vaccine Dosing

Patients with hematologic malignancies (HM) are at greater risk of severe morbidity and mortality caused by COVID19 and show a lower response to a two-dose COVID19 mRNA vaccine series. The primary objective of this retrospective cohort study is to explore the characteristics of the subset of patients with HM who had little to no change in SARS-CoV-2 spike antibody titer levels after a 3rd vaccine dose (3V) (-/-). As a secondary objective, we seek to compare the cohorts of patients who did and did not seroconvert post-3V to get a better understanding of the demographics and potential drivers of serostatus. A total of 625 patients with HM had two titer results at least 21 days apart pre- and post- the 3V dose. Among the participants who were seronegative prior to 3V (268), 149 (55.6%) seroconverted after the 3V dose and 119 (44.4%) did not. HM diagnosis was significantly associated with seroconversion status (P = .0003) with patients non-Hodgkin lymphoma 6 times the odds of not seroconverting compared to multiple myeloma patients (P = .0010). Among the cohort of patients who remained seronegative post-3V, 107 (90.0%) patients showed no reaction to 3V as indicated by pre- and post- 3V index values. This study focuses on an important subset of patients with HM who are not seroconverting after the COVID mRNA 3V, providing much needed data for clinicians to target and counsel this subset of patients.

Effects of Healthcare Policies and Reforms at the Primary Level in China: From the Evidence of Shenzhen Primary Care Reforms from 2018 to 2019.

Countries worldwide are making efforts to achieve health equity. China focuses on the implementation of the policy goal of "improving the primary level" to eliminate the health equity gap. The main purpose of this study is to examine the effects of the healthcare reforms at the primary level in China and to analyze the key factors that can help to improve their effectiveness. From the perspectives of the policy attention mechanism and public policy analysis, this study will explore primary care reforms from policy formulation to policy implementation on the basis of grounded theory and empirical research on primary care reforms in Shenzhen, China, that was conducted from 2018 to 2019. The present study found that the government pays close attention to the medical level and service level of primary care services at the policy formulation phase but less attention to talent level and information sharing. At the same time, this study combined with empirical data from primary care centers in Shenzhen for the period covering 2018 to 2019 evaluates policy implementation and its effect. Multiple regression analysis revealed that the medical level, talent level, service level, and information sharing helped to develop primary care services and improved health equity. Nevertheless, this study reflects a deviation between policy formulation and policy implementation for the development of primary care policies. Empirical experience shows that the development of talent level and information sharing can significantly promote primary care services and health management. Therefore, this study implies that in the process of promoting the health equity at the primary level, more attention should be paid to the consistency between policy formulation and policy implementation. Additionally, the policy promotion and influence mechanism can be improved, particularly in terms of talent development and information sharing, in order to effectively promote the development of health equity at the primary level.

Two R2R3-MYB genes cooperatively control trichome development and cuticular wax biosynthesis in Prunus persica.

The fruit surface has an enormous impact on the external appearance and postharvest shelf-life of fruit. Here, we report two functionally redundant genes, PpMYB25 and PpMYB26, involved in regulation of fruit skin texture in peach. PpMYB25 can activate transcription of PpMYB26 and they both induce trichome development and cuticular wax accumulation, resulting in peach fruit with a fuzzy and dull appearance. By contrast, nonfunctional mutation of PpMYB25 caused by an insertional retrotransposon in the last exon in nectarine fails to activate transcription of PpMYB26, resulting in nectarine fruit with a smooth and shiny appearance due to loss of trichome initiation and decreased cuticular wax accumulation. Secondary cell wall biosynthesis in peach fruit pubescence is controlled by a transcriptional regulatory network, including the master regulator PpNAC43 and its downstream MYB transcription factors such as PpMYB42, PpMYB46 and PpMYB83. Our results show that PpMYB25 and PpMYB26 coordinately regulate fruit pubescence and cuticular wax accumulation and their simultaneous perturbation results in the origin of nectarine, which is botanically classified as a subspecies of peach.

Which urban communities are susceptible to COVID-19? An empirical study through the lens of community resilience.

BACKGROUND: After the lockdown of Wuhan on January 23, 2020, the government used community-based pandemic prevention and control as the core strategy to fight the pandemic, and explored a set of standardized community pandemic prevention measures that were uniformly implemented throughout the city. One month later, the city announced its first lists of "high-risk" communities and COVID-19-free communities. Under the standardized measures of pandemic prevention and mitigation, why some communities showed a high degree of resilience and effectively avoided escalation, while the situation spun out of control in other communities? This study investigated: 1) key factors that affect the effective response of urban communities to the pandemic, and 2) types of COVID-19 susceptible communities. METHODS: This study employs the crisp-set qualitative comparative analysis method to explore the influencing variables and possible causal condition combination paths that affect community resilience during the pandemic outbreak. Relying on extreme-case approach, 26 high-risk communities and 14 COVID-19 free communities were selected as empirical research subjects from the lists announced by Wuhan government. The community resilience assessment framework that evaluates the communities' capacity on pandemic prevention and mitigation covers four dimensions, namely spatial resilience, capital resilience, social resilience, and governance resilience, each dimension is measured by one to three variables. RESULTS: The results of measuring the necessity of 7 single-condition variables found that the consistency index of "whether the physical structure of the community is favorable to virus transmission" reached 0.9, which constitutes a necessary condition for COVID-19 susceptible communities. By analyzing the seven condition configurations with high row coverage and unique coverage in the obtained complex solutions and intermediate solutions, we found that outbreaks are most likely to occur in communities populated by disadvantaged populations. However, if lacking spatial-, capital-, and governance resilience, middle-class and even wealthy communities could also become areas where COVID-19 spreads easily. CONCLUSIONS: Three types of communities namely vulnerable communities, alienated communities, and inefficient communities have lower risk resilience. Spatial resilience, rather than social resilience, constitutes the key influencing factor of COVID-19-susceptible communities, and the dual deficiencies of social resilience and governance resilience are the common features of these communities.

The MADS-box gene PpPI is a key regulator of the double-flower trait in peach.

Double flower is an invaluable trait in ornamental peach, but the mechanism underlying its development remains largely unknown. Here, we report the roles of ABCE model genes in double flower development in peach. A total of nine ABCE regulatory genes, including eight MADS-box genes and one AP2/EREBP gene, were identified in the peach genome. Subcellular localization assay showed that all the ABCE proteins were localized in the nucleus. Four genes, PpAP1, PpAP3, PpSEP3, and PpPI, showed a difference in expression levels between single and double flowers. Ectopic overexpression of PpPI increased petal number in Arabidopsis, while transgenic lines overexpressing PpAP3 or PpSEP3 were morphologically similar to wild-type. Ectopic overexpression of PpAP1 resulted in a significant decrease in the number of basal leaves and caused early flowering. These results suggest that PpPI is likely crucial for double flower development in peach. In addition, double flowers have petaloid sepals and stamens, and single flower could occasionally change to be double flower by converting stamens to petals in peach, suggesting that the double-flower trait is likely to have evolved from an ancestral single-flower structure. Our results provide new insights into mechanisms underlying the double-flower trait in peach.

Genome-wide identification, characterization and expression analysis of MATE family genes in apple (Malus × domestica Borkh).

BACKGROUND: As an important group of the multidrug efflux transporter family, the multidrug and toxic compound extrusion (MATE) family has a wide range of functions and is distributed in all kingdoms of living organisms. However, only two MATE genes in apple have been analyzed and genome-wide comprehensive analysis of MATE family is needed. RESULTS: In this study, a total of 66 MATE (MdMATE) candidates encoding putative MATE transporters were identified in the apple genome. These MdMATE genes were classified into four groups by phylogenetic analysis with MATE genes in Arabidopsis. Synteny analysis reveals that whole genome duplication (WGD) and segmental duplication events played a major role in the expansion of MATE gene family in apple. MdMATE genes show diverse expression patterns in different tissues/organs and developmental stages. Analysis of cis-regulatory elements in MdMATE promoter regions indicates that the function of MdMATE genes is mainly related to stress response. Besides, the changes of gene expression levels upon different pathogen infections reveal that MdMATE genes are involved in biotic stress response. CONCLUSIONS: In this work, we systematically identified MdMATE genes in apple genome using a set of bioinformatics approaches. Our comprehensive analysis provided valuable resources for improving disease resistance in apple and further functional characterization of MATE genes in other species.

Unraveling a genetic roadmap for improved taste in the domesticated apple.

Although taste is an important aspect of fruit quality, an understanding of its genetic control remains elusive in apple and other fruit crops. In this study, we conducted genomic sequence analysis of 497 Malus accessions and revealed erosion of genetic diversity caused by apple breeding and possible independent domestication events of dessert and cider apples. Signatures of selection for fruit acidity and size, but not for fruit sugar content, were detected during the processes of both domestication and improvement. Furthermore, we found that single mutations in major genes affecting fruit taste, including Ma1, MdTDT, and MdSOT2, dramatically decrease malate, citrate, and sorbitol accumulation, respectively, and correspond to important domestication events. Interestingly, Ma1 was identified to have pleiotropic effects on both organic acid content and sugar:acid ratio, suggesting that it plays a vital role in determining fruit taste. Fruit taste is unlikely to have been negatively affected by linkage drag associated with selection for larger fruit that resulted from the pyramiding of multiple genes with minor effects on fruit size. Collectively, our study provides new insights into the genetic basis of fruit quality and its evolutionary roadmap during apple domestication, pinpointing several candidate genes for genetic manipulation of fruit taste in apple.

Potential Association of Reactive Oxygen Species With Male Sterility in Peach.

Male sterility is an important agronomic trait for hybrid vigor utilization and hybrid seed production, but its underlying mechanisms remain to be uncovered. Here, we investigated the mechanisms of male sterility in peach using a combined cytology, physiology, and molecular approach. Cytological features of male sterility include deformed microspores and tapetum cells along with absence of pollen grains. Microspores had smaller nucleus at the mononuclear stage and were compressed into belts and subsequently disappeared in the anther cavity, whereas tapetum cells were swollen and vacuolated, with a delayed degradation to flowering time. Male sterile anthers had an ROS burst and lower levels of major antioxidants, which may cause abnormal development of microspores and tapetum, leading to male sterility in peach. In addition, the male sterility appears to be cytoplasmic in peach, which could be due to sequence variation in the mitochondrial genome. Our results are helpful for further investigation of the genetic mechanisms underlying male sterility in peach.

Behavioral Implementation and Compliance of Anti-Epidemic Policy in the COVID-19 Crisis.

Different countries have introduced different urgent policies to control the spread of the novel coronavirus. The compliance behavior of these anti-epidemic policies has always been an important concern to governments, and its effects need to be tested. In recent years, many scholars have paid attention to the mechanism and intervention of policy compliance behavior, which helps to explain the mechanism of anti-epidemic compliance behavior, and to improve the effectiveness of anti-epidemic policy. Therefore, considering the characters of youth groups in the context of the novel coronavirus, this study takes campus anti-epidemic compliance behavior as the research topic, based on 680 effective samples of college students in China, in order to examine the effectiveness of these policies using an investigation experiment. This study revealed that the 'Nudge' policy instrument was the most effective way to guide individuals' behavior during the coronavirus outbreak, the 'Sermon' instrument was the least recognized, and the 'Whip' instrument (a traditional and classical policy instrument) had its normal effect on individuals' behavior. Additionally, it found that high accessibility in policy implementation results in more significant policy behavior. By taking the effects of different policy behaviors into consideration, governments may produce better and more effective policy implementation and compliance during the anti-epidemic period.

A 1.7-Mb chromosomal inversion downstream of a PpOFP1 gene is responsible for flat fruit shape in peach.

Flat peaches have become popular worldwide due to their novelty and convenience. The peach flat fruit trait is genetically controlled by a single gene at the S locus, but its genetic basis remains unclear. Here, we report a 1.7-Mb chromosomal inversion downstream of a candidate gene encoding OVATE Family Protein, designated PpOFP1, as the causal mutation for the peach flat fruit trait. Genotyping of 727 peach cultivars revealed an occurrence of this large inversion in flat peaches, but absent in round peaches. Ectopic overexpression of PpOFP1 resulted in oval-shaped leaves and shortened siliques in Arabidopsis, suggesting its role in repressing cell elongation. Transcriptional activation of PpOFP1 by the chromosomal inversion may repress vertical elongation in flat-shaped fruits at early stages of development, resulting in the flat fruit shape. Moreover, PpOFP1 can interact with fruit elongation activator PpTRM17, suggesting a regulatory network controlling fruit shape in peach. Additionally, screening of peach wild relatives revealed an exclusive presence of the chromosomal inversion in P. ferganensis, supporting that this species is the ancestor of the domesticated peach. This study provides new insights into mechanisms underlying fruit shape evolution and molecular tools for genetic improvement of fruit shape trait in peach breeding programmes.