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This commentary focuses on a rising transnational queer Chinese digital culture—Girls' Love (GL) webtoons. I consider this queer women-focused entertainment as an epitome of the queer convergence of transnational flows, women's cultures, and digital platform technologies in today's Asia. My discussion sheds light on its multilayered queer-transnational characteristics, as well as the controversies surrounding its transcultural mediation of queer women. Rather than simplifying it as an anti-heterocentric Chinese convergence culture in an age of globalization and digitization, I highlight GL webtoons' role in stimulating various voices concerning women during transnational encounters of gender and sexual knowledge. [ABSTRACT FROM AUTHOR]

Background: Natural medicines present a considerable analytical challenge due to their diverse botanical origins and complex multi‐species composition. This inherent complexity complicates their rapid identification and analysis. Tangerine peel, a product of the Citrus species from the Rutaceae family, is widely used both as a culinary ingredient and in traditional Chinese medicine. It is classified into two primary types in China: Citri Reticulatae Pericarpium (CP) and Citri Reticulatae Pericarpium Viride (QP), differentiated by harvest time. A notable price disparity exists between CP and another variety, Citri reticulatae "Chachi" (GCP), with differences being based on the original variety. Methods: This study introduces an innovative method using portable miniature mass spectrometry for swift on‐site analysis of QP, CP, and GCP, requiring less than a minute per sample. And combined with machine learning to differentiate the three types on site, the method was used to try to distinguish GCP from different storage years. Results: This novel method using portable miniature mass spectrometry for swift on‐site analysis of tangerine peels enabled the characterization of 22 compounds in less than one minute per sample. The method simplifies sample processing and integrates machine learning to distinguish between the CP, QP, and GCP varieties. Moreover, a multiple‐perceptron neural network model is further employed to specifically differentiate between CP and GCP, addressing the significant price gap between them. Conclusions: The entire analytical time of the method is about 1 minute, and samples can be analyzed on site, greatly reducing the cost of testing. Besides, this approach is versatile, operates independently of location and environmental conditions, and offers a valuable tool for assessing the quality of natural medicines. [ABSTRACT FROM AUTHOR]

Renowned for their nutritional benefits, citrus fruits are harvested at various stages in China for functional food production. This study introduces an innovative analytical method, DART-MS, enabling direct qualitative analysis of citrus samples without the need for preprocessing. Simultaneously, the combination of chemometrics can be applied to distinguish between three different citrus samples: Citri Reticulatae Pericarpium, Citri Reticulatae Pericarpium Viride, and Citri Reticulatae "Chachi". Notably, given the international regulatory concerns surrounding synephrine, a precise quantitative analysis method for synephrine was developed. The limit of detection (LOD) and the limit of quantification (LOQ) were 39 ng mL−1 and 156 ng mL−1, respectively. The recovery rates obtained varied from 98.46% to 100.71%. Furthermore, the intra-day and inter-day precision demonstrated robust consistency, with values spanning 5.0–6.1% and 5.03–6.08%, respectively, offering quicker results compared to those from HPLC-MS, promising a safer assessment of herbal and food products. [ABSTRACT FROM AUTHOR]

Introduction: Fingered citron slices possess significant nutritional value and economic advantages as herbal products that are experiencing increasing demand. The grading of fingered citron slices plays a crucial role in the marketing strategy to maximize profits. However, due to the limited adoption of standardization practices and the decentralized structure of producers and distributors, the grading process of fingered citron slices requires substantial manpower and lead to a reduction in profitability. In order to provide authoritative, rapid and accurate grading standards for the market of fingered citron slices, this paper proposes a grading detection model for fingered citron slices based on improved YOLOv8n. Methods: Firstly, we obtained the raw materials of fingered citron slices from a dealer of Sichuan fingered citron origin in Shimian County, Ya'an City, Sichuan Province, China. Subsequently, high-resolution fingered citron slices images were taken using an experimental bench, and the dataset for grading detection of fingered citron slices was formed after manual screening and labelling. Based on this dataset, we chose YOLOv8n as the base model, and then replaced the YOLOv8n backbone structure with the Fasternet main module to improve the computational efficiency in the feature extraction process. Then we redesigned the PAN-FPN structure used in the original model with BiFPN structure to make full use of the high-resolution features to extend the sensory field of the model while balancing the computation amount and model volume, and finally we get the improved target detection algorithm YOLOv8-FCS. Results: The findings from the experiments indicated that this approach surpassed the conventional RT-DETR, Faster R-CNN, SSD300 and YOLOv8n models in most evaluation indicators. The experimental results show that the grading accuracy of the YOLOv8-FCS model reaches 98.1%, and the model size is only 6.4 M, and the FPS is 130.3. Discussion: The results suggest that our model offers both rapid and precise grading for fingered citron slices, holding significant practical value for promoting the advancement of automated grading systems tailored to fingered citron slices. [ABSTRACT FROM AUTHOR]

Citrus microcarpa is a popular nutritious fruit that is widely cultivated in China. In recent years, many compounds with significant pharmacological activities have been isolated successfully from the pericarp of C. microcarpa. However, to date, there are no reports on the activity of C. microcarpa pericarp against root-knot nematodes. This study used the ethanolic extract from the pericarp of Hainan C. microcarpa and the impregnation method to determine its activity on J2 Meloidogyne enterolobii specimens and on single-egg hatching. The results showed that when J2 individuals were treated with 50 mg.L-1 of the extract, the lethal concentration 50 values after 24 and 48 hours were 17.124 and 8.858 mg-mL-1, respectively. The mortality rate of nematodes after 48 hours of treatment was 100%, and the inhibition rate of single-egg hatching after 24 hours was 89.29%. The ethanolic extract of C. microcarpa peels showed high inhibitory and lethal activity against the M. enterolobii. The analysis of the chemical composition of the extract revealed 28 substances with insecticidal and antibacterial effects, including lignans, flavonoids, fatty acids, organic acids, terpenoids, and imidazole. The formulas of the chemical structures and pharmacological effects of these potential insecticidal and antibacterial substances were elucidated to provide a scientific basis and a theoretical reference for the use of C. microcarpa pericarps as a raw material for the development of new, natural plant nematicides. [ABSTRACT FROM AUTHOR]

Melanommataceous species exhibit high diversity with a cosmopolitan distribution worldwide and show a prominent saprobic lifestyle. In this study, we explored five saprobic species collected from plant litter substrates from terrestrial habitats in China and Thailand. A combination of morphological characteristics and multi-locus phylogenetic analyses was used to determine their taxonomic classifications. Maximum Likelihood and Bayesian Inference analyses of combined LSU , SSU , ITS and tef1-α sequence data were used to clarify the phylogenetic affinities of the species. Byssosphaeria poaceicola and Herpotrichia zingiberacearum are introduced as new species, while three new host records, Bertiella fici, By. siamensis and Melanomma populicola are also reported from litter of Cinnamomum verum, Citrus trifoliata and Fagus sylvatica, respectively. Yet, despite the rising interest in the melanommataceous species, there is a considerable gap in knowledge on their host associations and geographical distributions. Consequently, we compiled the host-species associations and geographical distributions of all the so far known melanommataceous species. [ABSTRACT FROM AUTHOR]

This review examines hesperidin, a citrus bioflavonoid, as a potential antiviral agent against SARS-CoV-2. The COVID-19 pandemic has demanded an urgent need to search for effective antiviral compounds, including those of natural origin, such as hesperidin. The review provides a comprehensive analysis of the chemical properties, bioavailability and antiviral mechanisms of hesperidin, particularly its potential efficacy against SARS-CoV-2. A review of databases, including PubMedPico, Scopus and Web of Science, was conducted using specific keywords and search criteria in accordance with PRISMA (Re-porting Items for Systematic Reviews and Meta-Analysis) guidelines between 2020 and 2024. Of the 207 articles, 37 were selected for the review. A key aspect is the correlation of in vitro, in silico and clinical studies on the antiviral effects of hesperidin with epidemiological data on citrus consumption in China during 2020–2024. The importance of integrating laboratory findings with actual consumption patterns to better understand the role of hesperidin in mitigating COVID-19 was highlighted, and an attempt was made to analyze epidemiological studies to examine the association between citrus juice consumption as a source of hesperidin and the incidence and severity of COVID-19 using China as an example. The review identifies consistencies and discrepancies between experimental and epidemiological data, highlighting the need to correlate the two fields to better understand the potential of hesperidin as an agent against SARS-CoV-2. Challenges and limitations in interpreting the results and future research perspectives in this area are discussed. The aim of this comprehensive review is to bridge the gap between experimental studies and epidemiological evidence and to contribute to the understanding of their correlation. [ABSTRACT FROM AUTHOR]

Endosymbionts regulate the behavior of pest species, which could provide insights into their control. The citrus leafminer (Phyllocnistis citrella Stainton) is a widely distributed pest associated with diseases of citrus, especially of young trees. Here, we determined the endosymbiont composition of P. citrella in citrus orchards across China. The resulting dataset comprised average 50,430 high-quality reads for bacterial 16S rRNA V3-V4 regions of endosymbionts from 36 P. citrella larvae sampled from 12 citrus orchards across China. The sequencing depth and sampling size of this dataset were sufficient to reveal most of the endosymbionts of P. citrella. In total, 2,875 bacterial amplicon sequence variants were obtained; taxonomic analysis revealed a total of 372 bacterial genera, most of which were Proteobacteria phylum with Undibacterium being the most abundant genus. This dataset provides the first evidence of P. citrella endosymbionts that could support the development of pest management approaches in citrus orchards. [ABSTRACT FROM AUTHOR]

Summary: Plenty of rainfall but unevenly seasonal distribution happens regularly in southern China. Seasonal drought from summer to early autumn leads to citrus fruit acidification, but how seasonal drought regulates citrate accumulation remains unknown.Herein, we employed a set of physiological, biochemical, and molecular approaches to reveal that CsABF3 responds to seasonal drought stress and modulates citrate accumulation in citrus fruits by directly regulating CsAN1 and CsPH8.Here, we demonstrated that irreversible acidification of citrus fruits is caused by drought lasting for > 30 d during the fruit enlargement stage. We investigated the transcriptome characteristics of fruits affected by drought and corroborated the pivotal roles of a bHLH transcription factor (CsAN1) and a P3A‐ATPase gene (CsPH8) in regulating citrate accumulation in response to drought. Abscisic acid (ABA)‐responsive element binding factor 3 (CsABF3) was upregulated by drought in an ABA‐dependent manner. CsABF3 activated CsAN1 and CsPH8 expression by directly and specifically binding to the ABA‐responsive elements (ABREs) in the promoters and positively regulated citrate accumulation.Taken together, this study sheds new light on the regulatory module ABA‐CsABF3‐CsAN1‐CsPH8 responsible for citrate accumulation under drought stress, which advances our understanding of quality formation of citrus fruit. [ABSTRACT FROM AUTHOR]

The citrus essential oil isolation has vast potential to valorize waste from the agro-industrial and food sectors. The objective of this work was to develop a review of patents on essential oil isolation systems from any plant and citrus essential oil isolation systems and/or methods. The technological search was carried out in the patent databases of Espacenet, Patentscope, Scopus, ScienceDirect, Google Patents, LENS ORG, and USPTO from 2000 to 2021. The results highlight that most of the inventions are from China and consist of isolation methods for citrus essential oil. The USA´s inventions stand out as systems that can be produced on a larger scale. The patent shares of the educational and private sectors are 26% and 74%, respectively. About 10.53% of patents protect commercially exploited products. Finally, an opportunity was detected to protect methods and/or systems that integrate renewable energy technologies. [ABSTRACT FROM AUTHOR]

Citrus fruits are the largest fruit crop in China. Post-harvest green mold is one of the major diseases that affect the quality and safety of citrus fruits, as it poses a risk of mycotoxins contamination. Current research primarily focuses on the infection mechanism of Penicillium digitatum, while other important Penicillium plays a significant role in citrus infection and toxin production. The mycotoxins produced can pose a serious threat to food safety. In this review, we provide an overview of the infection and toxin producing mechanisms of the main green mold fungi affecting citrus post-harvest, analyze the current research trends and directions in the field of citrus green mold disease, aiming to reduce the risk of fungal toxin contamination and promote quality improvement and efficiency in the citrus industry, providing new research perspectives for enhancing citrus quality and supporting industry development. [ABSTRACT FROM AUTHOR]

Citrus is the largest fruit in the world and in China, and its fruits are rich in flavonoids. Citrus flavonoids possess various beneficial biological activities, including antioxidant, anti-inflammatory, lipid-lowering, anticancer, bacteriostatic, and neuroprotective properties, which contribute to human health. However, citrus flavonoids face challenges such as poor solubility, stability, and low bioavailability, which restrict their application in industrial production. The development of a stable encapsulation has emerged as an effective approach to overcome these limitations. This paper aims to provide a comprehensive review of the research progress regarding the structure, types, and main encapsulation methods for citrus flavonoids, which have been investigated and will be analyzed in terms of their advantages and disadvantages. The effects of citrus flavonoids encapsulation on physiological activities will be summed up. Additionally, the effects and application of encapsulation on the main citrus flavonoids (naringin, hesperidin, neohesperidin, etc) will be summarized. The findings are expected to provide theoretical basis for the high -value utilization of citrus flavonoids in functional food, cosmetics, pharmaceuticals, and other related industries. [ABSTRACT FROM AUTHOR]

Introduction: Asian citrus psyllid (ACP, Diaphorina citri) is an important transmission vector of "Candidatus Liberibacter asiaticus" (CLas), the causal agent of Huanglongbing (HLB), the most destructive citrus disease in the world. As there are currently no HLB-resistant rootstocks or varieties, the control of ACP is an important way to prevent HLB. Some viruses of insect vectors can be used as genetically engineered materials to control insect vectors. Methods: To gain knowledge on viruses in ACP in China, the prevalence of five RNA and DNA viruses was successfully determined by optimizing reverse transcription polymerase chain reaction (RT-PCR) in individual adult ACPs. The five ACPassociated viruses were identified as follows: diaphorina citri bunyavirus 2, which was newly identified by high-throughput sequencing in our lab, diaphorina citri reovirus (DcRV), diaphorina citri picorna-like virus (DcPLV), diaphorina citri bunyavirus (DcBV), and diaphorina citri densovirus-like virus (DcDV). Results: DcPLV was the most prevalent and widespread ACP-associated virus, followed by DcBV, and it was detected in more than 50% of all samples tested. DcPLV was also demonstrated to propagate vertically and found more in salivary glands among different tissues. Approximately 60% of all adult insect samples were co-infected with more than one insect pathogen, including the five ACPassociated viruses and CLas. Discussion: This is the first time these viruses, including the newly identified ACPassociated virus, have been detected in individual adult ACPs from natural populations in China's five major citrus-producing provinces. These results provide valuable information about the prevalence of ACP-associated viruses in China, some of which have the potential to be used as biocontrol agents. In addition, analysis of the change in prevalence of pathogens in a single insect vector is the basis for understanding the interactions between CLas, ACP, and insect viruses. [ABSTRACT FROM AUTHOR]

Introduction: Citrus chlorotic dwarf-associated virus (CCDaV) is an economically important citrus virus associated with leaf curling, deformation, and chlorosis found in China. Plants have evolved RNA silencing to defend against viral infections; however, the mechanism by which CCDaV suppresses RNA silencing in citrus remains unknown. Methods: Six proteins encoded by CCDaV were ectopically expressed in Nicotiana benthamiana 16c using the pCHF3 vector to identify RNA-silencing suppression activities. Results: V2 protein encoded by CCDaV suppressed local RNA silencing and systemic RNA silencing triggered by GFP RNA, but did not impede short-distance movement of the RNA silencing signal in N. benthamiana 16c. GFP fluorescence observations showed that the ability of V2 protein to suppress RNA silencing was weaker than tomato bushy stunt virus P19. Deletion analysis showed that the putative nuclear localization signal (NLS, 25-54 aa) was involved in the RNA silencing suppression activity of V2 protein. Furthermore, V2 protein cannot block dsRNA-triggered RNA silencing. The subcellular localization assay suggested that V2 protein was localized to nucleus of N. benthamiana. Conclusion: Overall, the results of this study demonstrate that CCDaV-V2 acts as an activity of silencing suppression. This is the first reported RNA-silencing suppressor encoded by Citlodavirus and will be valuable in revealing the molecular mechanism of CCDaV infection. [ABSTRACT FROM AUTHOR]

Meyer lemon (Citrus × meyeri) is a hybrid citrus fruit from the Rutaceae family, originating from China. It is well-known for its distinctive appearance and flavor, as well as its healthnourishing nutrients. Micropropagation is an efficient alternative in the multiplication of plant stocks suitable for the commercial scale. The inclusion of organic additives in culture media has been found to provide a cost-effective option as a plant growth stimulant for in vitro plant development. The current study intends to assess the effects of coconut water and banana homogenate in the regeneration of Meyer lemon. In vitro, shoots were treated in half-strength Murashige and Skoog media fortified with 2 mg/L 6-benzylaminopurine with varying concentrations of coconut water and banana homogenate without sucrose. Results revealed that the treatment of 30% coconut water and 40 g/L banana homogenate resulted in the greatest proliferation of new shoots (3.00 ± 0.873 and 1.57 ± 0.297, respectively), whereas treatment of 40% coconut water resulted in the greatest shoot elongation of 0.239 ± 0.026 cm. The current study suggested the incorporation of coconut water and banana homogenate as potential substitutes for carbon sources and growth stimulants in the regeneration of Meyer lemon. [ABSTRACT FROM AUTHOR]

Citrus plants are prone to phosphorus (P) deficiency, especially in acidic soil, making them more dependent on root-associated endophytic fungi for growth and development. Beni-Madonna, a hybrid of Citrus nanko × C. amakusa, is a citrus known as "tangor" that is highly popular in China and other parts of the world due to its deep red color and jelly-like flesh. In this study, the inoculation response to two arbuscular mycorrhizal fungi (Diversispora versiformis, Dv; Funneliformis mosseae, Fm) and an endophytic fungus (Serendipita indica, Si) with regard to the growth, leaf gas exchange, light energy efficiency, P levels, acid phosphatase activity, and expression of the purple acid phosphatase (PAP) and phosphate transporter (PT) genes through a potted experiment using Beni-Madonna (tangor) citrus plants grafted on trifoliate orange (Poncirus trifoliata) was studied. Two years following inoculation, the root fungal colonization rates of inoculated plants were significantly increased, accompanied by an increase in plant height and stem diameter, with Si presenting the best effect. Fungal inoculations also significantly increased the leaf chlorophyll index, nitrogen-balance index, photosynthesis rate, stomatal conductance, transpiration rate, photosynthetic efficiency, and quantum yield of PSII, while it reduced photoinhibition and heat dissipation, with Si having the best effect on light energy efficiency. Si significantly increased leaf and root P levels, as well as root CsPAP1‒3, CsPT2, CsPT3, and CsPT7 expression and soil acid phosphatase activity; Fm in mycorrhizal fungi significantly increased leaf and root P levels, as well as root CsPT1 and CsPT7 expression and root/soil acid phosphatase activity. These observations suggested an advantage of Si over the other two AMF in terms of improved plant growth and P acquisition, while Fm displayed prominent effects on increased photosynthetic efficiency. [ABSTRACT FROM AUTHOR]

Xinjunan is a novel broad-spectrum fungicide developed in China. However, its excessive use may lead to the accumulation of toxic residue and increased health risks. In the present study, a simple method using liquid chromatography-tandem mass spectrometry was established, and multiple experiments were conducted in 12 regions of China to characterise the risk assessment of Xinjunan residues in cucumber, tomato, citrus (pulp), and citrus (whole). The calibration curve was linear with a correlation coefficient (r) >0.9951. The recovery rates of Xinjunan in three crops at different spiking levels (0.01 ~ 1 mg kg−1) were 77%~102%, with a relative standard deviation of 1%~10%. The terminal residues of Xinjunan in cucumber, tomato, citrus (pulp), and citrus (whole) were below 0.033, 0.01, 0.01, and 0.041 mg kg−1, respectively. The results showed a low concentration level of Xinjunan residues in cucumber, tomato, and citrus than the recommended dosage. The Chinese dietary structure and terminal residue analysis under field conditions showed the risk quotient (RQ) of Xinjunan to be 0.044, which was significantly lower than 1, suggesting the risk to be acceptable. Overall, the results indicated that Xinjunan in these crops exhibited no significant risk for the human diet. [ABSTRACT FROM AUTHOR]

The Asian citrus psyllid (ACP) is the main vector of Citrus Huanglongbing, the most damaging citrus disease, causing significant financial losses in the citrus industry. Global warming has expanded the habitat of this pest, allowing it to continue its northward migration to China. Population genetic information of ACP is fundamentally essential for species management. This study investigated the genetic diversity and population structure of Chinese ACP using the mitochondrial cytochrome oxidase subunit I gene by dataset comprised 721 sequences from 27 geographic sites in China. Low haplotype diversity (0.323 ± 0.022) and low nucleotide diversity (0.00071 ± 0.00007) were observed in the entire population, which may indicate recent founder events. Twenty-three haplotypes were identified and clustered into 2 haplogroups: haplogroup I and haplogroup II. Haplogroup II included only 2 unique haplotypes, which occurred exclusively in the Southwest China ACP population. Genetic differentiation analyses were also indicative of Southwest China population was significantly differentiated from the remaining populations. Demographic history analysis showed that ACP population in China has experienced demographic expansion. Our results provided a better understanding of the genetic distribution patterns and structures of ACP populations in China. [ABSTRACT FROM AUTHOR]

Purpose: This research is expected to shed light on soil contamination in citrus orchards and provide a reference for soil quality maintenance and improvement in orchards under the organic fertilizer substitution scenario. Materials and methods: Heavy metals (HMs) and veterinary antibiotics (VAs) in soils collected from citrus orchards in Meishan, Sichuan Province, China, were measured. Single factor index, potential ecological risk factor, and potential ecological risk index were employed to assess the contamination status and potential ecological risks of HMs in soils. Additionally, the risk of VAs was also evaluated based on their risk quotient values. Furthermore, Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis were employed to identify the potential sources of HMs and VAs in soils. Results and discussion: HMs and VAs exhibited great variance in the study area. Nickel (Ni) was the primary metallic contaminant, followed by cadmium (Cd), chromium (Cr), and arsenic (As). HMs accumulation in soils would not pose risks to the ecosystem. Atmospheric deposition and livestock manure could be the primary sources of HMs in soils. In terms of VAs, fluoroquinolones (FQs), sulfonamides (SAs), and tetracyclines (TCs) were the major VAs in soils, with the accumulative level averaged at 84.6 μg kg−1 (36.8–369 μg kg−1). Additionally, the residual VAs, except for enrofloxacin (ENR), would only pose limited to moderated risk to soil microbes or aqueous organisms. Conclusions: Clean and high-quality organic fertilizers, instead of livestock manure, were recommended to eliminate the potential environmental risks during organic fertilizer substitution. [ABSTRACT FROM AUTHOR]

China is one of the countries with the largest citrus cultivation areas, and its citrus industry has received significant attention due to its substantial economic benefits. Traditional manual forestry surveys and remote sensing image classification tasks are labor-intensive and time-consuming, resulting in low efficiency. Remote sensing technology holds great potential for obtaining spatial information on citrus orchards on a large scale. This study proposes a lightweight model for citrus plantation extraction that combines the DeepLabV3+ model with the convolutional block attention module (CBAM) attention mechanism, with a focus on the phenological growth characteristics of citrus in the Guangxi region. The objective is to address issues such as inaccurate extraction of citrus edges in high-resolution images, misclassification and omissions caused by intra-class differences, as well as the large number of network parameters and long training time found in classical semantic segmentation models. To reduce parameter count and improve training speed, the MobileNetV2 lightweight network is used as a replacement for the Xception backbone network in DeepLabV3+. Additionally, the CBAM is introduced to extract citrus features more accurately and efficiently. Moreover, in consideration of the growth characteristics of citrus, this study augments the feature input with additional channels to better capture and utilize key phenological features of citrus, thereby enhancing the accuracy of citrus recognition. The results demonstrate that the improved DeepLabV3+ model exhibits high reliability in citrus recognition and extraction, achieving an overall accuracy (OA) of 96.23%, a mean pixel accuracy (mPA) of 83.79%, and a mean intersection over union (mIoU) of 85.40%. These metrics represent an improvement of 11.16%, 14.88%, and 14.98%, respectively, compared to the original DeepLabV3+ model. Furthermore, when compared to classical semantic segmentation models, such as UNet and PSPNet, the proposed model achieves higher recognition accuracy. Additionally, the improved DeepLabV3+ model demonstrates a significant reduction in both parameters and training time. Generalization experiments conducted in Nanning, Guangxi Province, further validate the model's strong generalization capabilities. Overall, this study emphasizes extraction accuracy, reduction in parameter count, adherence to timeliness requirements, and facilitation of rapid and accurate extraction of citrus plantation areas, presenting promising application prospects. [ABSTRACT FROM AUTHOR]

Species in Diaporthe have broad host ranges and cosmopolitan geographic distributions, occurring as endophytes, saprobes and plant pathogens. Previous studies have indicated that many Diaporthe species are associated with Citrus. To further determine the diversity of Diaporthe species associated with citrus diseases in China, we conducted extensive surveys in major citrus-producing areas from 2017-2020. Diseased tissues were collected from leaves, fruits, twigs, branches and trunks showing a range of symptoms including melanose, dieback, gummosis, wood decay and canker. Based on phylogenetic comparisons of DNA sequences of the internal transcribed spacer regions (ITS), calmodulin (cal), histone H3 (his3), translation elongation factor 1-alpha (tef1) and beta-tubulin (tub2), 393 isolates from 10 provinces were identified as belonging to 36 species of Diaporthe, including 32 known species, namely D. apiculata, D. biconispora, D. biguttulata, D. caryae, D. citri, D. citriasiana, D. compacta, D. discoidispora, D. endophytica, D. eres, D. fusicola, D. fulvicolor, D. guangxiensis, D. hongkongensis, D. hubeiensis, D. limonicola, D. litchii, D. novem, D. passifloricola, D. penetriteum, D. pescicola, D. pometiae, D. sackstonii, D. sennicola, D. sojae, D. spinosa, D. subclavata, D. tectonae, D. tibetensis, D. unshiuensis, D. velutina and D. xishuangbanica, and four new species, namely D. gammata, D. jishouensis, D. ruiliensis and D. sexualispora. Among the 32 known species, 14 are reported for the first time on Citrus, and two are newly reported from China. Among the 36 species, D. citri was the dominant species as exemplified by its high frequency of isolation and virulence. Pathogenicity tests indicated that most Diaporthe species obtained in this study were weakly aggressive or non-pathogenic to the tested citrus varieties. Only D. citri produced the longest lesion lengths on citrus shoots and induced melanose on citrus leaves. These results further demonstrated that a rich diversity of Diaporthe species occupy Citrus, but only a few species are harmful and D. citri is the main pathogen for Citrus in China. The present study provides a basis from which targeted monitoring, prevention and control measures can be developed. [ABSTRACT FROM AUTHOR]

Online sales are essential for linking smallholder farmers to a wide range of markets. In essence, online sales not only influence the income received from selling a specific product but also generate spillover effects on total farm income and household income because they promote the sales of other agricultural products and generate regional off-farm work opportunities (e.g. product sorting, packaging, and delivery). Taking citrus as an example, this study explores the income effects of online sales with a focus on net returns from citrus production, net farm income, and household income. We used an endogenous treatment regression model to address the self-selection bias issues of online sales and estimated data collected from 926 citrus-producing households in Jiangxi Province, China. The results show that online citrus sales boost income growth in rural China. Specifically, online sales significantly increased net returns from citrus production, net farm income, and household income by 5,000 Yuan/capita, 8,580 Yuan/capita, and 17,830 Yuan/capita, respectively. The income-enhancing effects of online sales are greater for female household heads than they are for their male counterparts. Our findings emphasise the importance of promoting online sales to improve rural household welfare. [ABSTRACT FROM AUTHOR]

In recent decades, China has made significant strides in food and nutrition security, yet challenges persist in the western rural regions, especially in Guangxi. Farming households in this area face heightened vulnerability due to limited arable land and environmental hazards, leading to increased efforts to boost income through horticultural crop farming. This study explores the impact of citrus farming and crop diversification on household dietary diversity within the context of the existing literature, examining trade-offs between subsistence and income-generating farming. Using OLS regression techniques and a mediating effect model, the analysis focuses on distinct contexts within citrus farming, utilizing survey data from households engaged in the cultivation of both citrus and non-citrus. Results reveal that while citrus cultivation moderately contributes to dietary diversity, its primary influence lies in encouraging farmers to diversify food purchases, with the mediating effect from market purchases exceeding 50%. Diversifying crop production, including staple crops and vegetables alongside citrus, proves more effective in enhancing dietary diversity among citrus farming households. Crop diversification positively influences dietary diversity, partially addressing household self-sufficiency. While extensive crop diversification may not be the ultimate solution to food security challenges, promoting specific diversification systems shows promise in the context of sustainable agriculture goals. [ABSTRACT FROM AUTHOR]

• Chloroplast genome of 'Zangju' had one less protein-coding gene (rpl22) than 'Tuju'. • There were high commonality of codons and a significant AT preference in chloroplast genomes of the two citrus varieties. • The chloroplast genomes of different citrus species could share one haplotype. • Citrus species had complex lineage relationships and extensive hybridization. Citrus plants, comprising some of the most widely cultivated fruit crops worldwide, have great research value. We assembled and annotated the chloroplast genomes of two local important citrus varieties of China, 'Tuju' and 'Zangju', and comparatively analyzed their sequences. The full lengths chloroplast genomes of 'Tuju' and 'Zangju' were 160,121 and 160,694 bp, respectively. Both featured a quadripartite structure with two copies of a large inverted repeat (IR) separated by small (SSC) and large (LSC) single-copy regions. 'Tuju' chloroplast genome contained 134 genes. 'Zangju' had one less protein-coding gene (rpl22) than 'Tuju'. We also found 27 and 21 optimal codons, all of which ended with A or U, for chloroplast protein-coding genes of 'Tuju' and 'Zangju', respectively. There were 32 haplotypes obtained from 43 citrus chloroplast genomes, some different species or cultivars could share one haplotype. Of them, 'Tuju', one individual of Citrus limon , one individual of Citrus maxima and Citrus platymamma shared one haplotype, which implied they had the same maternal origin. The phylogenetic trees supported that all haplotypes could be divided five groups, while haplotype network analysis tended to get three groups. Our study reveals the complex lineage relationship of citrus plants at a certain level, and provides a valuable reference tool for future research on citrus plants. [ABSTRACT FROM AUTHOR]

Both of the two citrus diseases, Alternaria brown spot (ABS) and Anthracnose, caused by Alternaria and Colletotrichum spp., respectively, can produce leaf lesions which are hard to differentiate. These two diseases have been confused as causal agents of brown spot for over a decade in China. In this study, citrus leaves with or without brown spot were collected from Zhaoqing, Guangdong and Wanzhou, Chongqing, and were further used for the taxonomic and functional comparisons between the co-occurring Alternaria and Colletotrichum species. In the amplicon sequencing, the average relative abundance and the composition of Alternaria, but not Colletotrichum, increased (from 0.1 to 9.9, p = 0.059; and to 0.7, p < 0.05) and significantly altered (p < 0.01) with the brown spot in Zhaoqing and Wanzhou, respectively. Two representative isolates Alternaria sp. F12A and Colletotrichum sp. F12C, from the same brown spot, were proved with different virulence and host response activation to citrus leaves. F12A caused typical symptoms of brown spot with the average spot length expanded to 5 and 6.1 cm, and also altered the citrus global gene expression 48 and 72 h after inoculation. In addition, F12A enriched the expression of genes that were most frequently involved in plant defense. In comparison, F12C caused leaf spot limited to the wounded site, and its milder activation of host response recovered 72 h after inoculation. Our study indicates that the incidence of brown spot in China is caused by Alternaria species, and the ABS should be a fungal disease of major concern on citrus. [ABSTRACT FROM AUTHOR]

In this study, the transcendental logarithmic cost function model was used to measure the rate of technological progress in seven major mandarin-producing regions and seven major tangerine-producing regions in China from 2006 to 2021. The modified gravity model was used to establish spatial correlation networks. The social network analysis method was used to analyze the characteristics of the overall network structure and the individual network structure of the spatial correlation networks of citrus-production technology progress, and the quadratic assignment procedure was used to analyze the factors influencing the spatial network. The results show the production of Chinese mandarins and tangerines is in the stage of technological progress in general, but the rate of progress is slowing down gradually, and the rate of mandarin-production technology progress is higher than that of tangerine-production technology progress. In terms of the overall network structure characteristics, the spatial networks of technological progress related to Chinese mandarin and tangerine production are becoming increasingly dense and complex, with obvious spatial spillover effects, but the network structure is relatively loose, and the polarization of the tangerine network is more serious. In terms of individual network structure characteristics, the relatively economically developed eastern regions have a higher status in terms of the spatial correlation network and a stronger role in controlling and dominating the resource elements needed for citrus-production technology progress. Education, informatization, economic development, innovation support, and financial support are important factors influencing the formation of the spatial association network of citrus-production technology progress in China. [ABSTRACT FROM AUTHOR]

Aiming to address the problem of low mechanisation of filling and transporting citrus seedling pots in China, a new type of pot filling and transporting machine with 120 pots at a time was designed. Based on the study of flow characteristics of the seedling substrate, key components of the filling and transporting machines, such as the hopper component, transmission mechanism, flip mechanism, and steering mechanism, were designed. The effects of the opening width of the hopper, the rotating speed of the stirring shaft, the moisture content of the seedling substrate, and the forward speed of the transporting device on the filling effect of the seedling pot were studied by the experimental method, and the optimal operation parameters were determined. The prototype tests were repeated 3 times with the best combination of parameters. The test results indicate that the machine was in good condition for loading and unloading. The number of filling pots was 120 once, and the average filling time was 40 s. The average filling mass was 1.881 kg, 0.006 kg different from the predicted value of 1.887 kg, and the relative error was 0.32%. The coefficient of variation of the mass was 2.97%, which was 0.12% different from the predicted value of 2.85%, and the relative error was 4.0%. This designed machine can provide a reference for developing and optimising the citrus substrate filling and transporting machine. [ABSTRACT FROM AUTHOR]

Citrus fruit, the most abundant global fruit, is primarily concentrated in China. Mulching techniques have demonstrated a favorable effect on the soil's hydrothermal environment, resulting in enhanced plant growth, yield, and quality. Nevertheless, the impact of mulching on the soil microbiome and fruit quality of Beni Madonna tangor (Citrus nanko × C. amakusa) remains unknown. This study aimed to examine the impact of different mulching techniques, namely traditional flat planting (CK), reflective film mulching (RM), black film mulching (BM), corn stalk mulching (CS), green film mulching (GM), and transparent plastic film mulching (TM), on the bacterial diversity, composition, cooccurrence networks, and bulk soil assembly during the ripening stage of Beni Madonna tangor. The various treatments employed in this study exhibited distinct impacts on fruit quality and soil temperature and humidity. Through comprehensively evaluating fruit quality and soil properties, it was found that RM treatment had the best effect, while CK treatment was the worst. The mulching results in a significant decrease in the Shannon indexcompared to the control group. Specifically, mulching with RM, CS, and GM led to a significant increase in Chloroflexi abundance (p < 0.05). Furthermore, the interaction complexity between bacteria was found to be lower under GM and TM treatments compared to the other mulching treatments. At the genus level, Chloroflexi exhibited a positive correlation with total soluble solid (TSS) and Vitamin C (Vc) contents, however, GP13 showed a converse result. It was determined that Chloroflexi, with a high abundance of RM, promoted an improvement in soil and fruit quality. Ultimately, it can be concluded that various mulching techniques yield distinct impacts on both the soil bacterial composition and citrus quality, with these effects being intricately linked to the core biota's functionalities within each treatment. [ABSTRACT FROM AUTHOR]

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Finger citron (Citrus medica L. var. sarcodactylis (Hoola van Nooten) Swingle; Rutaceae: Citrus) is an important plant for both medicine and food. Due to the lack of suitability analysis, many problems have arisen in its planting. According to the daily observation data, Kriging interpolation was selected to spatialize precipitation and temperature data. MaxEnt and ArcGIS were applied to simulate the suitable areas of finger citron in China from the perspectives of bioclimate, soil, topographic factors and human activities in 2050s and 2090s. Results showed that temperature annual range (Bio7), annual precipitation (Bio12), human footprint (Hf), elevation (El) and precipitation seasonality (Bio15) were identified as the dominant environmental variables related to the distribution of finger citron. Spatiotemporal distribution of annual precipitation (Bio12) showed that in the future, the precipitation in South China tends to decrease first (2050s) and then increase (2090s). The spatio-temporal analysis of temperature annual range (Bio7) showed that the 20-30 °C region was relatively stable in the Sichuan Basin and the middle and lower reaches of the Pearl River Basin. Under the future climate change scenarios, the total suitable area showed a significant increase trend in 2090s, and the change of most, moderately and poorly suitable habitats showed no obv ious law. Under SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios, the centroid of the most suitable habitat of finger citron would move to the northwest, southeast and southwest respectively. Our results can effectively carry out to promote the recovery of its population. [ABSTRACT FROM AUTHOR]

Consumers are becoming more concerned about pesticide residues in food. Since citrus represent a significant portion of the diet, it is appropriate to monitor the pesticide residues in citrus. In this paper, we modified a QuEChERS method combined with HPLC-MS/MS to investigate residue levels of 15 pesticides and 3 metabolites in citrus (whole fruit and pulp) and orange juice from the markets in China. And the dietary exposure risks were evaluated by using the hazard quotient (HQ) and hazard index (HI) methods based on deterministic and probabilistic models. The recoveries of the modified method ranged from 70 to 112% at three spike levels of 0.005–0.5 mg/kg with relative standard deviations of 1.0–18.1%. Pesticide residues were detected in 85.84% of the whole citrus and 40.00% of pulp, with concentrations ranging from 0.005 to 0.47 mg/kg, which did not exceed their maximum residue limits (MRLs) in China. The HQ (0.01–11.41%) and HI (0.07–16.2%) were both less than 100%, demonstrating that chronic, acute, and cumulative dietary risks were acceptable. Notably, the risk for children (1–6 years old, 1.96–16.2%) was higher than that for the general population (0.76–6.25%). The results of our study can provide a valuable reference for regular monitoring to protect public health and ensure pesticide management. [ABSTRACT FROM AUTHOR]

In view of the continuous decline in organic carbon content in citrus orchard soil, to explore the effects of biochar and farmland waste on the transformation of organic carbon in citrus orchard soil. In this study, the soil of a citrus orchard in Yangshuo County, Guilin, Guangxi, China, was collected. The citrus peel and the Cipangopaludina chinensis shell were used as raw materials, the citrus peel was used to prepare biochar, and the Cipangopaludina chinensis shell was powdered. The materials were added to the soil in different proportions. A 30-day indoor incubation soil was conducted to investigate the effects of adding different proportions of citrus peel biochar and Cipangopaludina chinensis shell powder on the transformation of organic carbon in citrus orchard soil. Compared with the control group, the addition of 4% orange peel biochar, 2% orange peel biochar + 2% Cipangopaludina chinensis shell powder, 2.6% orange peel residue biochar + 1.3% Cipangopaludina chinensis shell powder, and 3% orange peel biochar + 1% Cipangopaludina chinensis shell powder increased soil organic carbon by 22.49%, 20.06%, 19.81%, and 21.35%, respectively. Compared with the control, 2.6% orange peel biochar + 1.3% Cipangopaludina chinensis shell powder had the best effect on the improvement of soil organic carbon components, and microbial biomass carbon (MBC), dissolved organic carbon (DOC) and readily oxidized organic carbon (ROC) increased by 19.81%, 64.88%, 67.81%, and 19.44%, respectively. Different proportions of orange peel residue biochar and Cipangopaludina chinensis shell powder were applied to the soil of the citrus orchard to effectively increase the soil organic carbon component content and enzyme activities. This study provides a theoretical basis for the carbon sequestration mechanism of citrus orchard soil using different proportions of orange peel residue biochar and Cipangopaludina chinensis shell powder. [ABSTRACT FROM AUTHOR]

Fungicides are often used to extend the storage time of postharvest satsuma mandarin fruit. In recent years, fungicide residue has become an issue of food safety. This study aimed to investigate the distribution and migration of three typical fungicides (imazalil, prochloraz, thiophanate-methyl) in postharvest satsuma mandarins using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Three fungicides could quickly penetrate satsuma mandarins and their gradient concentrations of residues in the fruit were: carpopodium > mesocarp > epicarp > pulp. However, the residues of three fungicides in the edible pulp were obviously lower than the maximum residue limit (MRL = 5.0 mg/kg in China). Residues of the three fungicides decreased in epicarp and carpopodium but increased in mesocarp and pulp during storage. Fungicides could quickly penetrate the fruit, settling primarily in the carpopodium but little in the pulp. Both epicarp and carpopodium were the breakthrough pathways for the fungicides entering the fruit, while epicarp was the main route for the penetration of fungicides. These findings shed new information on the behavior of fungicides and the safety issue of satsuma mandarins. [ABSTRACT FROM AUTHOR]

Conservation of crop wild relatives is critical for plant breeding and food security. The lack of clarity on the genetic factors that lead to endangered status or extinction create difficulties when attempting to develop concrete recommendations for conserving a citrus wild relative: the wild relatives of crops. Here, we evaluate the conservation of wild kumquat (Fortunella hindsii) using genomic, geographical, environmental, and phenotypic data, and forward simulations. Genome resequencing data from 73 accessions from the Fortunella genus were combined to investigate population structure, demography, inbreeding, introgression, and genetic load. Population structure was correlated with reproductive type (i.e., sexual and apomictic) and with a significant differentiation within the sexually reproducing population. The effective population size for one of the sexually reproducing subpopulations has recently declined to ~1,000, resulting in high levels of inbreeding. In particular, we found that 58% of the ecological niche overlapped between wild and cultivated populations and that there was extensive introgression into wild samples from cultivated populations. Interestingly, the introgression pattern and accumulation of genetic load may be influenced by the type of reproduction. In wild apomictic samples, the introgressed regions were primarily heterozygous, and genome-wide deleterious variants were hidden in the heterozygous state. In contrast, wild sexually reproducing samples carried a higher recessive deleterious burden. Furthermore, we also found that sexually reproducing samples were self-incompatible, which prevented the reduction of genetic diversity by selfing. Our population genomic analyses provide specific recommendations for distinct reproductive types and monitoring during conservation. This study highlights the genomic landscape of a wild relative of citrus and provides recommendations for the conservation of crop wild relatives. Author summary: Conservation genomics offers a comprehensive approach to understand the underlying genetic and environmental factors affecting the conservation of species. Despite its importance, the conservation genomics of most crop wild relatives remains poorly understood. In this study, we investigated the population fragmentation, inbreeding, gene flow, and genetic load of a citrus wild relative, Fortunella hindsii, using a combination of genomic, geographical, environmental, and phenotypic data, as well as forward simulations. Fortunella hindsii, listed on the registry of National Key Protected Wild Plants in China, has two types of reproduction, sexual and apomictic. Conservation genomics provided insights into the genetic diversity and structure, which are critical for developing effective conservation strategies. Our analysis also helped to assess the risks of hybridization and introgression from cultivated to wild populations. We found that different patterns of introgression and genetic load may be influenced by reproductive type; for example, deleterious variants may hide in the heterozygous state in apomictic populations. Sexually reproducing samples with the self-incompatibility mechanism can prevent rapid loss of genetic diversity caused by selfing. This study serves as an example of conservation genomics and the importance of utilizing important wild relatives of crops to inform broader conservation efforts. [ABSTRACT FROM AUTHOR]

Citrus has become a pivotal industry for the rapid development of agriculture and increasing farmers' incomes in the main production areas of southern China. Knowing how to diagnose and control citrus huanglongbing has always been a challenge for fruit farmers. To promptly recognize the diagnosis of citrus huanglongbing, a new classification model of citrus huanglongbing was established based on MobileNetV2 with a convolutional block attention module (CBAM-MobileNetV2) and transfer learning. First, the convolution features were extracted using convolution modules to capture high-level object-based information. Second, an attention module was utilized to capture interesting semantic information. Third, the convolution module and attention module were combined to fuse these two types of information. Last, a new fully connected layer and a softmax layer were established. The collected 751 citrus huanglongbing images, with sizes of 3648 × 2736, were divided into early, middle, and late leaf images with different disease degrees, and were enhanced to 6008 leaf images with sizes of 512 × 512, including 2360 early citrus huanglongbing images, 2024 middle citrus huanglongbing images, and 1624 late citrus huanglongbing images. In total, 80% and 20% of the collected citrus huanglongbing images were assigned to the training set and the test set, respectively. The effects of different transfer learning methods, different model training effects, and initial learning rates on model performance were analyzed. The results show that with the same model and initial learning rate, the transfer learning method of parameter fine tuning was obviously better than the transfer learning method of parameter freezing, and that the recognition accuracy of the test set improved by 1.02~13.6%. The recognition accuracy of the citrus huanglongbing image recognition model based on CBAM-MobileNetV2 and transfer learning was 98.75% at an initial learning rate of 0.001, and the loss value was 0.0748. The accuracy rates of the MobileNetV2, Xception, and InceptionV3 network models were 98.14%, 96.96%, and 97.55%, respectively, and the effect was not as significant as that of CBAM-MobileNetV2. Therefore, based on CBAM-MobileNetV2 and transfer learning, an image recognition model of citrus huanglongbing images with high recognition accuracy could be constructed. [ABSTRACT FROM AUTHOR]

Citrus is a crucial agricultural commodity of the hilly subtropical regions of southern China. Attempts in recent years to combat the destructive disease Huanglongbing (HLB) have led to citrus orchards being covered with insect-proof screens (IPS). Understanding which citrus orchards are covered by IPS is crucial for regional water and soil conservation, as well as control of plastic pollution. However, monitoring of orchards is complicated by IPS spectral interference in remotely sensed image classification. Here, an optimal feature combination scheme is developed and tested for mapping citrus orchards that use IPS. Seasonal Sentinel-2 images from 2021 were used to define indices for vegetation, plastic mulch, red edge, and texture. These were combined with topographic and land surface temperature using random forest classification to determine optimal feature discrimination combinations for orchards in Xunwu County, Jiangxi Province. Results show: (1) significantly higher visible light reflectance from IPS orchards ensures spectral discrimination between IPS covered and uncovered orchards. (2) After feature optimization, the seasonal spectral band has the highest accuracy (86%) in single feature classification. The addition of conventional indices and topographic-temperature features improves classification to 92%. (3) Xunwu County had 460 km2 of citrus orchard cover in 2021, with 88 km2 (19%) of that total being covered with IPS. Our method effectively and accurately maps citrus orchards with or without IPS coverage at 10 m resolution. The effective monitoring of large-scale IPS in other regions can now support the development of local and regional sustainable agricultural policies. [ABSTRACT FROM AUTHOR]

Specialization may lead to higher income for small-scale farmers but comes with increased risks, while diversification can mitigate risks and foster agricultural sustainability. Considering the influences of complex risks and farmers' subjective risk aversion, the decision for small-scale farmers to specialize in citrus cultivation or diversify with multiple crops remains uncertain. There is currently limited understanding of this issue among citrus smallholders in rural China. This study aims to fill this empirical gap by examining the impact of smallholder farmers' subjective risk aversion on their choice between citrus monoculture and crop diversification. It utilizes a subjective risk assessment approach that incorporates farmers' risk perceptions and risk attitudes towards citrus farming. Farm crop diversification is assessed through the utilization of both the count index and Shannon index. The empirical analysis employs survey data obtained from citrus growers in Guangxi, China, and applies an instrumental variable regression method with endogeneity consideration using the IV-Probit model and 2SLS model estimation. The results reveal that both risk perceptions and risk attitudes play important roles in citrus smallholders' land allocation decisions. Specifically, citrus farmers who perceive higher risks and adopt risk-averse attitudes are statistically more inclined to engage in land use diversification practices, including the practice of growing citrus as well as other crops, which contributes to reducing the risks of citrus farming and promoting local environmental conservation. These results contribute to a better scholarly comprehension of the relationship between risk perceptions, risk attitudes, and crop diversification among small-scale citrus farmers. They provide valuable insights for enhancing the sustainability of land use systems with citrus farming while also emphasizing the importance of maintaining essential diversification in small-scale farming throughout the process of agricultural modernization. [ABSTRACT FROM AUTHOR]

Bactrocera tsuneonis and Bactrocera minax are the most destructive pests that damage citrus in China. These key pests hinder the citrus trade, cause significant financial losses, drastically lower citrus production and quality, and decrease farmer enthusiasm for citrus planting. Bactrocera minax and B. tsuneonis are very similar in all life stages. There are limited morphological characteristics to differentiate the adult species, and it is nearly impossible to differentiate these two species in the egg and larval stages. Loop-mediated isothermal amplification (LAMP) is a rapid and robust diagnostic tool used to identify these two species accurately. We designed two sets of primers to distinguish B. minax and B. tsuneonis using DNA barcoding region of the COI gene. Only 50 min was needed under a constant temperature of 65ºC to determine the species of the two flies. The reaction system has high specificity and sensitivity, in which these two species can be accurately distinguished between different geographical populations and 1.0 ng/μL was the lowest DNA concentration that could be detected. Our primers can quickly identify these key pests without knowing their morphology, which could facilitate plant protection workers at the primary level to solve problems in plant quarantine. [ABSTRACT FROM AUTHOR]

In this study, the DEA–Malmquist index method was used to measure the total factor productivity of citrus in seven major mandarin-producing provinces and seven major tangerine-producing provinces in China from 2006 to 2020. Moran's I index was used to test the spatial correlation of total factor productivity of mandarin and tangerine, and its σ convergence and β convergence characteristics were explored using coefficient of variation and spatial panel models. The results show that from the perspective of time series evolution, the growth rate of total factor productivity of mandarin and tangerine in China slowed down year by year after reaching the maximum value in 2008. Technological progress was the main factor affecting the total factor productivity of citrus. The total factor productivity growth of tangerine was more stable than that of mandarin, and the pure technical efficiency index and scale efficiency change index of mandarin and tangerine were not stable. From the perspective of regional differences, the total factor productivity of China's main citrus-producing provinces all indicated positive growth, showing an increasing trend from east to west. The drivers of growth were mainly technological progress and scale efficiency. The regional differences in total factor productivity growth for mandarin were more obvious than for tangerine. The total factor productivity of mandarin and tangerine showed obvious spatial correlation characteristics; the positive spatial spillover effect was significant; and there were σ convergence, absolute β convergence, and conditional β convergence. Regional disparities in citrus industry development can be more objectively reflected by convergence analysis that takes spatial factors, economic and social factors, and other factors into account. [ABSTRACT FROM AUTHOR]

Citrus chlorotic dwarf-associated virus (CCDaV) is a Citlodavirus species in the Geminiviridae family that causes tremendous economic loss to the citrus industry in China. Some proteins encoded by geminiviruses are crucial for the interaction between the virus and its host plant. However, the exact functions of CCDaV-encoded proteins such as CCDaV-RepA have not been investigated. This study presents evidence that CCDaV-RepA elicits a hypersensitive response (HR)-like cell death in Nicotiana benthamiana that was accompanied by the production of H2O2 and ion leakage, which suggested that CCDaV-RepA is a potential recognition target for inducing host defense responses. Furthermore, the rolling-circle replication motifs of CCDaV-RepA are associated with triggering HR-like cell death in N. benthamiana. Confocal microscopy and deletion mutagenesis assays showed that CCDaV-RepA was located in the nucleus, while the first eight amino acids (aa) at the N terminus and two regions located between aa residues 122-263 and 220-264 of RepA were not associated with nuclear localization. Tobacco rattle virus-induced gene silencing of the key signaling cascade components revealed that HR-like cell death induced by RepA was inhibited in WRKY1-silenced N. benthamiana. Moreover, WRKY1 expression was upregulated in RepA-GFP infiltrated Overall, the results suggest that NbWRKY1 positively regulated CCDaV-RepA -induced cell death in N. benthamiana. These findings provide novel information for further research on the interactions between CCDaV and the host plant. [ABSTRACT FROM AUTHOR]

Background: Citrus fruits are economically and nutritionally important but have been severely affected by Huanglongbing disease (HLB), its natural spread is mainly by the Asian Citrus Psyllid,Diaphorina citri Kuwayama (Hemiptera: Liviidae). Chemicals are often used to control this pest, but this is not sustainable. Meanwhile, there are few environmentally friendly bioinsecticides to control D. citri in China. Results: In this study, an entomofungal pathogen wz-1 was isolated from a D. citri carcass in the field, which resulted in a cumulative mortality rate of 75.27% in adult D. citri 7 days after inoculation of the spore suspension. It was identified as Cladosporium subuliforme based on morphological analysis as well as sequence analysis of several molecular markers (Internal Transcribed Spacers, Translation Elongation Factor 1-α and Actin). Remarkably, the lethality rate of adult D. citri reached 53.13%, 48 h after treatment with the aqueous phase extracts of wz-1. Hydroxyquinoline and phytosphingosine in the extracts were identified as potentially active metabolites using LC–MS. Conclusions: The entomopathogenicity and bioinsecticidal potential of C. subuliforme were previously unknown. Obtained results showed that both spores and extracts of wz-1 can effectively kill adult D. citri, providing an available fungal resource and a theoretical basis for biocontrol of the HLB insect vector D. citri. [ABSTRACT FROM AUTHOR]

Phyllosticta spp. are important pathogens of citrus plants. Several Phyllosticta species associated with Citrus species grown in China have been reported; however, the relative prevalences of individual species and the distributions of their genotypes among host Citrus species remain largely unknown. In this study, we conducted an extensive survey of Phyllosticta species across 11 citrus-producing provinces in southern China. From fruits and leaves with black spots or black-spot-like symptoms, a total of 461 Phyllosticta strains were isolated. Based on molecular (ITS, actA, tef1, gapdh, LSU, and rpb2 sequences) and morphological data, the strains were systematically identified as belonging to five species: P. capitalensis, P. citrichinaensis, P. citriasiana, P. citricarpa, and P. paracitricarpa. To further understand intraspecific genetic diversity and relationships, strains of five species from different geographic and host sources were analyzed based on the multilocus sequence data. Our population genetic analyses revealed that all five Phyllosticta species on citrus showed evidence for clonal dispersals within and among geographic regions. In addition, pathogenicity tests using representative strains showed that all five species can cause disease on the tested Citrus spp. We discuss the implications of our results for the control and management of Citrus Black Spot and related diseases. [ABSTRACT FROM AUTHOR]

The concentration and distribution of functional nitrogen (N) in citrus leaves can be significant indicators for the formation and transportation of fruit assimilation. A non-destructive monitoring model can be used for the functional nitrogen concentration in the leaves. The N application can also be adjusted to quantify the citrus nitrogen using hyperspectral technology. The five-year ‘Chunjian’ orange was taken as the experimental material in the Changshou District of Chongqing in China. The control treatments of nitrogen application with the different gradients were set: N0, N1, N2, and N3 (Nitrogen application qualities were 0, 50, 100, and 200 g/plant, respectively). The adjusted nitrogen treatments were named Nr1, Nr2, and Nr3, according to the non-destructive monitoring model for the functional nitrogen concentration in the citrus leaf. In the first year of the experiment, the leaves of the spring shoot (the second to fourth leaves from the top to the bottom) were collected at the fruit expansion and color-changed period, respectively. Sixteen leaves were randomly selected from each tree, according to the four directions of “south, east, north, west”, where the spectral values were determined simultaneously. A non-destructive monitoring model was then established for the functional nitrogen concentration in the citrus fruit leaves at the fruit expansion and color-changed period by the hyperspectral technique. In the second year, the leaf functional nitrogen concentration (LFNC) model and topdressing formula were used to calculate the actual nitrogen application ratio. The fertilizer of the actual nitrogen application ratio was applied in the adjusted N application treatments at the fruit expansion and color-changed period. A comparison was made to clarify the effects of control and adjusted nitrogen application on the yield, fruit quality, and nitrogen use efficiency. The results show that the LFNC model performed the higher accuracy using the back propagation neural network, where the R² were 0.78 (fruit expansion period) and 0.77 (fruit color-changed period). The Nr1 and Nr3 treatments increased the yield by 5.49, and 4.43 kg/ plant with the rate of increments of 48% and 40%, respectively, compared with the N1 and N3. Compared with the N1, the single fruit weight and soluble solid content of the citrus increased significantly by the adjusted N treatment Nr1. However, there was no change in the transverse and longitudinal diameter of the citrus fruits and fruit shape index between the control and adjusted N treatments. The partial factor productivity of applied (PFP-N) of adjusted N application treatments with the Nr1 was 10% lower than that of the control with the N1. There was only a little change in the fruit shape index and soluble solids of Nr3. Specifically, the single fruit weight increased compared with the N3. compared with the N3. The agronomic efficiency of the Nr2 and Nr3 increased by 290% and 364%, compared with the N1 and N3, respectively. There was no significant difference in the yield, quality, and nitrogen use efficiency between the Nr2 and N2. In conclusion, the adjusted nitrogen application using the non-destructive monitoring model of the citrus leaf functional nitrogen concentration can be expected to reduce the effects of insufficient or excessive nitrogen application on the citrus yield and quality, in order to improve the nitrogen partial productivity and agronomic efficiency. The finding can provide the theoretical basis and technical support to realize the non-destructive monitoring of functional nitrogen concentration in the citrus leaves and adjusted nitrogen application. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB) is the most harmful bacterial disease in citrus production in the world, and has been seriously ravaging the citrus groves of South China since the 1930s. The surveillance of the epidemiological characteristics of HLB is of utmost priority for citrus production in this region. In order to explore the effects of disease control measures, analyses on the space–time statistical features of the HLB epidemic, from 2019 to 2021, within six orchards in the Guangdong province are presented. Overall, the number of citrus plants in the orchards usually slightly decreased year by year. The reduction was mainly related to the level of plant susceptibility, which is correlated with citrus varieties. The maximum disease severity (incidence and race increment) was correlated with the awareness of this disease and the management intensity applied by the manager. A higher disease index was found in the conventional management orchards than in the comprehensive prevention and control orchards. Proper insect-protective screen houses can effectively prevent the epidemic of HLB, without affecting the fruit quality, and can also aid with higher yields. A high correlation was found between the geometry and topography of orchards and the HLB epidemic due to the wind direction from May to September and the Asia citrus psyllid activity characteristics. For flat orchards, the incidence of HLB in the north and entrance areas was higher than that in the southwest. In the mountain area, the incidence of the windward side in the south was higher than that of the leeward side in the north. Diseased trees tended to have an edge effect in the grove, whereas the trees of the same disease scale were found clustered in their distribution. These results allow a better understanding of HLB epidemiology and provide guidance for the early warning of HLB in new groves in areas that are severely affected by this disease. Furthermore, they also provide a scientific basis for the comprehensive prevention and control of HLB in old groves. [ABSTRACT FROM AUTHOR]

Interveinal chlorosis in old leaves is a common occurrence in citrus orchards in southern China. The present study investigates the 'Langfeng' navel orange (LF, Citrus sinensis) grafted onto a Trifoliate orange (TO, Poncirus trifoliata) rootstock, which exhibits healthy green leaves, and the 'Newhall' navel orange (NHE, C. sinensis) grafted onto TO, which has typical magnesium (Mg) deficiency-induced chlorosis. Chemical analysis of the rhizosphere soil revealed that the pH values were around 3.92 and that both Mg and calcium (Ca) were significantly deficient in the rhizosphere soil of both grafting combinations (LF/TO and NHE/TO). Furthermore, the chlorotic leaves of NHE/TO had significantly lower levels of Mg, Ca, and phosphorus (P), and the green leaves of NHE/TO had significantly lower levels of Mg and Ca compared to the green leaves of the LF/TO. This suggests that Mg deficiency may be the primary cause of chlorosis in NHE/TO. A greenhouse study using the same graft combinations showed that the LF/TO plants had better growth than the NHE/TO, possibly by promoting Mg uptake and/or improving Mg distribution to leaves, thereby increasing carbon dioxide (CO 2) assimilation and photosynthesis, optimizing carbohydrate distribution, and increasing plant biomass. This results in a phenotype that is tolerant to Mg deficiency. In conclusion, these findings suggest that the LF navel orange could be utilized in the development of new citrus varieties with improved Mg-use efficiency. • Interveinal chlorosis is common in southern China citrus orchards. • Study compares "Langfeng" navel orange (LF) on Trifoliate orange rootstock (TO) to "Newhall" navel orange (NHE) on TO. • Soil analysis showed Mg and Ca deficiencies and NHE/TO had lower levels of Mg, Ca, and P in chlorotic leaves. • Greenhouse study showed better growth in LF/TO plants, indicating improved Mg uptake and tolerance to Mg deficiency. • Findings suggest LF navel orange can be used in new citrus varieties with improved Mg-use efficiency. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), is an important pest of citrus in China, where pesticides are commonly used in citrus orchards. In order to reduce the use of chemical pesticides against P. citri and the development of resistance, the screening of biological control agents has attracted the attention of students. In this study, seven plant essential oils with high toxicity were selected from 40 plant essential oils by the leaf-dip bioassay, including plant essential oils of lemongrass, patchouli, juniper berry, sage, clove, frankincense, and citrus. The LC50 after 72 h treatment were 3.198 μL/mL, 8.312 μL/mL, 3.244 μL/mL, 6.701 μL/mL, 8.350 μL/mL, 21.953 μL/mL, and 8.788 μL/mL, respectively. According to the LT50, the essential oils' acute toxicity to P. citri from high to low were lemongrass, juniper berry, patchouli, citrus, sage, vetiver, and frankincense essential oils. In general, lemongrass and juniper berry essential oils have the best acaricidal effect and have high application value for the biological control of P. citri, which provides a basis for the development of botanical acaricides. [ABSTRACT FROM AUTHOR]

Purpose : In central China, N fertilizer reduction and green manure planting are dominant measures used by the government to improve N use efficiency in citrus orchards, but the effects on nutrient loss in runoff are unclear. This study aimed to determine the effects of those two measures on N and P losses in runoff in citrus orchards in central China. Materials and methods: This 2-year field experiment included four N fertilizer rate treatments (CK: 0 kg N ha−1 year−1 of urea; N1: 259.9 kg N ha−1 year−1 of urea; N2: 315.6 kg N ha−1 year−1 of urea; N3: 371.3 kg N ha−1 year−1 of urea, the conventional N fertilizer rate) and four green manure treatments (CKG: 0 kg N ha−1 year−1 of urea plus green manure; N1G: 259.9 kg N ha−1 year−1 of urea plus green manure; N2G: 315.6 kg N ha−1 year−1 of urea plus green manure; N3G: 371.3 kg N ha−1 year−1 of urea plus green manure). The sowing rate of green manure is 75.0 kg ha−1 year−1, and the green manure was covered on the soil surface after being harvested. Results and discussion: Results indicated that a 30% (N1) and 15% (N2) reduction of fertilizer N reduced the cumulative total N (TN) loss by 31 ± 10% and 28 ± 8%, but increased the cumulative total P (TP) loss by 33 ± 26% and 21 ± 24% compared to conventional N fertilizer rates (N3). During the growing stage, green manure reduced TN loss by 15 ± 11%. During the ground mulching stage, green manure increased TN and TP losses by 21 ± 2% and 37 ± 21%, respectively. Both N fertilizer reduction and green manure planting had no significant effect on citrus yield and quality. Conclusions: Overall, we suggest that a 30% reduction in mineral fertilizer N combined with legume green manure planting (not mulching on the soil surface after harvested) is a better fertilization strategy that can reduce N and P losses in runoff in Hubei, China. [ABSTRACT FROM AUTHOR]

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key vector of the causal agents of Huanglongbing (HLB), a devastating disease affecting citrus almost worldwide. Nicotiana tabacum L. is an important commercial crop in China. Field observations suggested that D. citri adults die on N. tabacum leaves when grown nearby citrus orchards. In this study, the preference for and survivorship of D. citri adults on N. tabacum and their feeding behavior were investigated. The results showed that D. citri adults were attracted to N. tabacum and to the green leaf volatiles (GLVs) (Z)-3-hexenol and (E)-2-hexenol. The survival of D. citri adults on N. tabacum was less than 30 h, which was shorter than that for adults without food (35 h) and on a suitable host Murraya exotica L. (29 days). Electrical penetration graph (EPG) recordings revealed that the pathway phase of D. citri on N. tabacum leaves consisted of four waveforms--the non-probing phase (NP), the pathway phase (PP, including intercellular probing of activity in the phloem (C) and phloem penetration (D)), phloem salivation (E1), and phloem ingestion (E2). Diaphorina citri only secreted saliva and ingested sap from phloem on N. tabacum leaves and spent the longest duration in phloem sap ingestion (E2). Moreover, L-nicotine, an important defense compound against insects in N. tabacum plants, was highly toxic to D. citri. These results suggested that N. tabacum plants could help to sustainably control the spread of D. citri and HLB when growing in and around citrus orchards. [ABSTRACT FROM AUTHOR]

In order to address the problem of citrus seedling pot filling and transporting which is time-consuming and labor-intensive in China, a scheme for seedling pot filling and placing was proposed, and a self-propelled citrus seedling pot filling and placing machine was designed which can fill and place 48 pots at one time. Firstly, the rotary hopper door mechanism was designed, the movement of the hopper door was analyzed, and the connection between the opening size and the movement time of the hopper door was determined. Then, the transmission system of the machine was designed, the power consumption of the hopper movement and substrate stirring were calculated, and the power requirement of the transmission system was determined. The lifting structure of the seedling pots frame was analyzed, the size of the flipping structure of the cover plate was calculated, and the seedling pots frame was designed. After that, the substrate flow rate curve was measured through the substrate flow rate experiments, and the hopper-controlled movement speed was calculated. Furthermore, the experimental prototype was manufactured and tested. The test results indicate that the filling number of pots was 48 one time, the filling time was 30 s, and the seedling pots were fully filled and placed in order. The average filling mass of the seedling pots was 2.23 kg, and the average mass variation coefficient was 2.7%. The substrate mass which is scraped out is 0.81 kg, accounting for 0.76% of the total filling mass at one time. This designed machine had a reasonable structure and high filling efficiency. The reseach can provide a reference for the development and optimization of the citrus seedling pots filling and transporting machine. [ABSTRACT FROM AUTHOR]

In this study, we identified a new citrus vein enation virus (CVEV) isolate (named CVEV-DT1) through sRNA high-throughput sequencing and traditional sequencing. Phylogenetic analysis based on whole genome sequences of all known CVEV isolates revealed that CVEV-DT1 was in an evolutionary branch with other isolates from China. Molecular variation analysis showed that the single nucleotide variability along CVEV full-length sequences was less than 8%, with more transitions (60.55%) than transversions (39.43%), indicating a genetically homogeneous CVEV population. In addition, non-synonymous nucleotide mutations mainly occurred in ORF1 and ORF2. Based on disorder analysis of all encoded ORF by CVEV-DT1, we identified that the CVEV-DT1 coat protein (CP) formed spherical granules, mainly in the cell nucleus and partly throughout the cytoplasm, with liquid properties through subcellular localization and photobleaching assay. Furthermore, we also confirmed that the CVEV P0 protein has weak post-transcriptional RNA-silencing suppressor activity and could elicit a strong hypersensitive response (HR) in tobacco plants. Collectively, to the best of our knowledge, our study was the first to profile the genomic variation in all the reported CVEV isolates and reveal the functions of CVEV-DT1-encoded proteins. [ABSTRACT FROM AUTHOR]