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Huanglongbing (HLB) is a fatal citrus disease that is currently threatening citrus varieties worldwide. One putative causative agent, Candidatus Liberibacter asiaticus (CLas), is vectored by Diaphorina citri, known as the Asian citrus psyllid (ACP). Understanding the details of CLas infection in HLB disease has been hindered by its Candidatus nature and the inability to confidently detect it in diseased trees during the asymptomatic stage. To identify early changes in citrus metabolism in response to inoculation of CLas using its natural psyllid vector, leaves from Madam Vinous sweet orange (Citrus sinensis (L.) Osbeck) trees were exposed to CLas-positive ACP or CLas-negative ACP and longitudinally analyzed using transcriptomics (RNA sequencing), proteomics (liquid chromatography-tandem mass spectrometry; data available in Dryad: 10.25338/B83H1Z), and metabolomics (proton nuclear magnetic resonance). At 4 weeks postexposure (wpe) to psyllids, the initial HLB plant response was primarily to the ACP and, to a lesser extent, the presence or absence of CLas. Additionally, analysis of 4, 8, 12, and 16 wpe identified 17 genes and one protein as consistently differentially expressed between leaves exposed to CLas-positive ACP versus CLas-negative ACP. This study informs identification of early detection molecular targets and contributes to a broader understanding of vector-transmitted plant pathogen interactions.

A simple aqueous host:guest sensing array can selectively discriminate between different types of citrus varietal from peel extract samples. It can also distinguish between identical citrus samples at varying stages of ripening. The discrimination effects stem from detection of changes in the terpenoid composition of the peel extracts by the host:guest array, despite the overwhelming excess of a single component, limonene, in each sample. The hosts are insensitive to limonene but bind other monoterpenes strongly, even though they are similar in structure to the major limonene component. This work demonstrates the capability of host:guest arrays in sensing target molecules in environments with the competing agents present at high abundances in the sample matrix.

This study aimed to assess the antioxidant capacity of lemon flavonoid extract Eriomin® (LE) and its impact on cholesterol metabolism in the context of healthy aging. We orally treated 24-month-old male Wistar rats with an LE (40 mg/kg) suspended in 0.3 mL of sunflower oil. At the same time, control groups received an equal volume of sunflower oil (CON) or remained untreated (ICON) daily for 4 weeks. We examined LEs effects on superoxide dismutase and catalase- and glutathione-related enzyme activities, the concentration of lipid peroxides and protein carbonyls, total oxidant status (TOS) and antioxidant status (TAS), and oxidative stress index (OSI) in the liver, jejunum, and ileum. We also measured total cholesterol, its biosynthetic precursors (lanosterol, lathosterol, desmosterol), its degradation products (bile acid precursors) in the serum, liver, jejunum, and ileum, and serum phytosterols (intestinal absorption markers). LE reduced TOS, TAS, and OSI (p < 0.05) compared with control values, indicating its consistent antioxidant action in all examined organs. LE lowered hepatic desmosterol (p < 0.05) while also reducing 7α- and 24-hydroxycholesterol levels in the liver and ileum (p < 0.01). Serum cholesterol, hepatic gene expression, and the immunostaining intensity of CYP7A1 were unchanged. In conclusion, LE exerted non-enzymatic antioxidant effects and reduced cholesterol degradation, reducing its biosynthesis products, thereby maintaining serum cholesterol levels.

The Asian Citrus Psyllid (ACP), Diaphorina citri, is a vector of the pathological bacterium Candidatus Liberibacter asiaticus (CLas), which causes the most devastating disease to the citrus industry worldwide, known as greening or huanglongbing (HLB). Earlier field tests with an acetic acid-based lure in greening-free, Valencia citrus orange groves in California showed promising results. The same type of lures tested in São Paulo, Brazil, showed unsettling results. During the unsuccessful trials, we noticed a relatively large proportion of females in the field, ultimately leading us to test field-collected males and females for Wolbachia and CLas. The results showed high rates of Wolbachia and CLas infection in field populations. We then compared the olfactory responses of laboratory-raised, CLas-free, and CLas-infected males to acetic acid. As previously reported, CLas-uninfected males responded to acetic acid at 1 µg. Surprisingly, CLas-infected males required 50 × higher doses of the putative sex pheromone, thus explaining the failure to capture CLas-infected males in the field. CLas infection was also manifested in electrophysiological responses. Electroantennogram responses from CLas-infected ACP males were significantly higher than those obtained with uninfected males. To the best of our knowledge, this is the first report of a pathogen infection affecting a vectors response to a sex attractant.

Roof rats (Rattus rattus) are an invasive rodent that can cause substantial damage in citrus orchards. Their populations appear to be expanding throughout California, yet little is known about efficacious, cost-effective strategies to manage this invasive pest while minimizing pesticide use. Therefore, we developed two Integrated Pest Management (IPM) programs based on results of recent studies that incorporated observations of roof rat movement patterns, compared monitoring tools, and tested trapping and baiting options. Both IPM programs utilized elevated bait stations containing 0.005% diphacinone-treated oats and trapping, and we compared those programs to a bait-station only approach to determine which strategies were most practical. Initial IPM plots included a combination of elevated bait stations followed by a brief snap-trapping program and a longer-duration trapping program with Goodnature® A24 traps to hopefully keep rat numbers at low levels (Trial 1). Although initial bait applications were effective at reducing rat numbers, populations quickly rebounded within both the bait station only and IPM treatment areas within two-months following the completion of the baiting programs. Additionally, costs for this initial IPM approach were almost five times as much as a bait station approach. Our second IPM strategy (Trial 2) again incorporated an initial bait application period to knock down roof rat populations, followed by the use of trapping tunnels that contained two snap traps to further reduce/maintain rat numbers longer-term. We again observed effective knockdown with bait applications. However, in contrast to Trial 1, we observed substantial success with trapping tunnels at maintaining, and even increasing, overall efficacy within IPM plots, and IPM plots were always more efficacious than bait station only plots. Although the bait station only approach was less costly than the IPM approach used in Trial 2, the cost disparity was substantially less than that for Trial 1, and the cost difference disappeared during subsequent years, indicating long-term cost-effectiveness of this IPM approach. Collectively, the relatively low cost and high efficacy of a management program that incorporates initial bait applications to knock down roof rat populations, followed by a long-term snap-trapping program to maintain low densities, should provide an effective strategy for managing roof rats in citrus orchards.

Rapid advancements in technologies provide various tools to analyze fruit crop genomes to better understand genetic diversity and relationships and aid in breeding. Genome-wide single nucleotide polymorphism (SNP) genotyping arrays offer highly multiplexed assays at a relatively low cost per data point. We report the development and validation of 1.4M SNP Axiom® Citrus HD Genotyping Array (Citrus 15AX 1 and Citrus 15AX 2) and 58K SNP Axiom® Citrus Genotyping Arrays for Citrus and close relatives. SNPs represented were chosen from a citrus variant discovery panel consisting of 41 diverse whole-genome re-sequenced accessions of Citrus and close relatives, including eight progenitor citrus species. SNPs chosen mainly target putative genic regions of the genome and are accurately called in both Citrus and its closely related genera while providing good coverage of the nuclear and chloroplast genomes. Reproducibility of the arrays was nearly 100%, with a large majority of the SNPs classified as the most stringent class of markers, "PolyHighResolution" (PHR) polymorphisms. Concordance between SNP calls in sequence data and array data average 98%. Phylogenies generated with array data were similar to those with comparable sequence data and little affected by 3 to 5% genotyping error. Both arrays are publicly available.

Summary Autophagy is a conserved degradation pathway that regulates the clearance of paternal substrate at the early embryogenesis stage of animals. However, its mode of action is likely different in plants, which can regenerate through apomixis without fertilisation. Somatic embryogenesis (SE) is a unique plant process widely used for plant propagation and germplasm utilisation. Here, we studied citrus as an example and found a higher autophagic activity after SE initiation. Interestingly, amyloplasts were frequently found inside autophagosomes, whereas the inhibition of autophagy blocks amyloplasts/starch degradation and hinders somatic embryo formation. Furthermore, the consumption of storage lipids was faster in autophagy mutants, suggesting lipid metabolism is activated when starch utilisation is blocked. Exogenous application of autophagy‐inducing chemicals (e.g. spermidine) significantly promoted the formation of autophagosomes and increased SE efficiency, indicating a positive correlation between autophagy, energy metabolism, and somatic embryo formation in citrus. Taken together, our study unveils a pathway for the degradation of plant‐specific organelles and provides an effective approach for plant propagation. [ABSTRACT FROM AUTHOR]

Bioactive compounds play an increasingly prominent role in breeding functional and nutritive fruit crops such as citrus. However, the genomic and metabolic bases for the selection and differentiation underlying bioactive compound variations in citrus remain poorly understood. In this study, we constructed a species-level variation atlas of genomes and metabolomes using 299 citrus accessions. A total of 19 829 significant SNPs were targeted to 653 annotated metabolites, among which multiple significant signals were identified for secondary metabolites, especially flavonoids. Significant differential accumulation of bioactive compounds in the phenylpropane pathway, mainly flavonoids and coumarins, was unveiled across ancestral citrus species during differentiation, which is likely associated with the divergent haplotype distribution and/or expression profiles of relevant genes, including p -coumaroyl coenzyme A 2′-hydroxylases, flavone synthases, cytochrome P450 enzymes, prenyltransferases, and uridine diphosphate glycosyltransferases. Moreover, we systematically evaluated the beneficial bioactivities such as the antioxidant and anticancer capacities of 219 citrus varieties, and identified robust associations between distinct bioactivities and specific metabolites. Collectively, these findings provide citrus breeding options for enrichment of beneficial flavonoids and avoidance of potential risk of coumarins. Our study will accelerate the application of genomic and metabolic engineering strategies in developing modern healthy citrus cultivars. This study performed resequencing and wide-targeted metabolomic analysis on 299 citrus accessions, revealing the genetic basis of differential selection of bioactive compounds in citrus population through selective sweep analysis and mGWAS. Combined with large-scale bioactivity evaluation, potential citrus varieties and metabolites related to specific biological activities were screened, and the variation route of bioactivities alongside the evolution of citrus population was clarified. This study provided new insights for the selection and utilization of citrus resources as well as breeding improvement. [ABSTRACT FROM AUTHOR]

In citrus, the synthetic auxin 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA), applied as a foliar spray at a concentration of 15 mg l− 1 during physiological fruitlet abscission, caused additional fruitlet drop and reduced the number of fruits reaching maturity. The effect was much more pronounced at full physiological abscission than after. In this study, this thinning effect was successfully exploited for the first time in sour orange trees grown in an urban environment, reducing harvesting costs by up to almost 40%. This effect is mediated by the leaves, which alter their photosynthetic activity. Our results show a reduction of carbon fixation and sucrose synthesis in the leaf, by 3,5,6-TPA repression of the RbcS, SUS1 and SUSA genes, its transport to the fruit, as shown by the reduced expression of the sucrose transporter genes SUT3 and SUT4, and its hydrolysis in the fruit, mainly by repression of the SUS1 gene expression. Genes involved in auxin homeostasis in the fruit, TRN2 and PIN1, were also repressed. The coordinated repression of all these genes is consistent with the decrease in the fruit cell division rate, as shown by the repression of CYCA1-1 gene, leading to the production of ethylene, which ultimately induces fruitlet abscission. [ABSTRACT FROM AUTHOR]

Citrus tristeza virus (CTV) is a causal agent of diseases that have challenged the global citrus production for more than a century. The disease named 'tristeza', which means 'sadness' in Portuguese and Spanish, has spread by aphids and vegetative propagation, resulting in costly pandemics that reshaped the world citrus production by forcing the adaption of disease‐tolerant rootstocks. Furthermore, management of the second major CTV‐induced disease, stem pitting, became a unique example of the use of cross‐protection on a large nationwide scale, allowing many citrus growing regions to control the disease that could not be managed through horticultural practices. The information gathered in this review commemorates a hundred years of research on the virus and the respective diseases, which began with classical horticultural approaches and advanced toward the cutting‐edge molecular biology studies. In this regard, it is proper to mention that CTV research greatly benefited from close international collaboration between research institutions and scientists from the affected and nonaffected citrus areas. Moreover, despite the considerable initial losses caused by tristeza, the world's fresh fruit and juice concentrate citrus industries reemerged as highly productive following the research advancements, a situation that changed throughout Florida and Brazil in the past two decades or so with the outbreak of the devastating citrus greening (Huanglongbing) bacterial disease. This review encompasses past and recent advances in the CTV research positioning the citrus‐CTV pathosystem as a pivotal model system for investigating virus interactions with perennial woody hosts. The review will also serve as an updated version of the respective section on CTV in the Description of Plant Viruses that the Association of Applied Biologists manages. We dedicated this review to the 85th Birthday celebration of Prof. Moshe Bar‐Joseph, a world‐renowned plant pathologist whose half‐a‐century‐long career devoted to citrus diseases yielded many important, pioneering discoveries on CTV and other closteroviruses. Many of those are highlighted in this review. Prof. Bar‐Joseph retired from the Volcani Center, Agricultural Research Organization in Israel several years ago, yet he continues to be actively engaged in research and provides his expertise to citrus pathologists around the world in the present days. [ABSTRACT FROM AUTHOR]

Citrus bacterial canker (CBC) is resulted from Xanthomonas citri subsp. citri (Xcc) infection and poses a significant threat to citrus production. Glutathione S-transferases (GSTs) are critical in maintaining redox homeostasis in plants, especially in relation to abiotic and biotic stress responses. However, the function of GSTs in resisting CBC remains unclear. Here, citrus glutathione S-transferases were investigated applying a genome-wide approach. In total, 69 CsGSTs belonging to seven classes were identified, and the phylogeny, chromosomal distribution, gene structures and conserved motifs were analyzed. Several CsGSTs responded to Xcc infection, as observed in the upregulation of CsGSTF1 and CsGSTU18 in the CBC-sensitive 'Wanjincheng' variety but not in the resistant 'Kumquat' variety. CsGSTF1 and CsGSTU18 were localized at the cytoplasm. Transient overexpression of CsGSTF1 and CsGSTU18 mediated reactive oxygen species (ROS) scavenging, whereas the virus-induced gene silencing (VIGS) of CsGSTF1 and CsGSTU18 caused strong CBC resistance and ROS burst. The present study investigated the characterization of citrus GST gene family, and discovered that CsGSTF1 and CsGSTU18 negatively contributed to CBC through modulating ROS homeostasis. These findings emphasize the significance of GSTs in infection resistance in plants. [ABSTRACT FROM AUTHOR]

Hesperidin is a dihydroflavonoids, accounting for more than 50% of the total flavonoids in Citri Reticulatae Pericarpium (CRP) of traditional Chinese medicine. It is an effective antioxidant and free radical scavenger that has anti-inflammatory, antiviral and hypoglycemic properties. The latest studies reported that hesperidin has a potential for novel coronavirus resistance. However, little is known about the synthesis regulation and accumulation site of hesperidin in plants. In this study, hesperidin synthase gene Crc1,6RhaT was cloned, and the protein can be completely transformed flavanone-7-O-glucoside into hesperidin in vitro and in vivo. Studies on biological characteristics of ovary walls and exocarps showed that the relative expression levels of the Crc1,6RhaT gene and protein decreased gradually with the development of citrus fruits, and the relative content of hesperidin firstly increased, then sequentially decreased. In situ hybridization results further revealed that Crc1,6RhaT transcription was mainly concentrated in the secretory cavity cells, which are revealed to be the site of flavonoid synthesis. Immunocytochemistry localization results showed that the Crc1,6RhaT was mainly located in the endoplasmic reticulum, nucleus and vacuole of secretory cells. We inferred that the Crc1,6RhaT was synthesized in the endoplasmic reticulum, then was transported into the vacuoles through enlarged vesicles at the end of the endoplasmic reticulum. Our results not only revealed that Crc1,6RhaT may be involved in the synthesis of hesperidin of the main bioactive substance in the medicinal plant Citrus reticulata 'Chachi' fruit, but also provided novel insights into the main subcellular sites of hesperidin biosynthesis in vacuoles. [ABSTRACT FROM AUTHOR]

Key message: Abnormal expression of genes regulating anther and pollen development and insufficient accumulation of male sterility (MS)- related metabolites lead to MS in cybrid pummelo Male sterility (MS) is a major cause of seedlessness in citrus, which is an important trait for fresh fruit. Understanding the mechanism of MS is important for breeding seedless citrus cultivars. In this study, we dissected the transcriptional, metabolic and physiological mechanisms of MS in somatic cybrid of pummelo (G1 + HBP). G1 + HBP exhibited severe male sterility, manifesting as retarded anther differentiation, abnormal anther wall development (especially tapetum and endothecium), and deficient pollen wall formation. In the anthers of G1 + HBP, the expression of genes regulating anther differentiation and tapetum development was abnormal, and the expression of genes regulating endothecium secondary lignification thickening and pollen wall formation was down-regulated. The transcription of genes involved in MS-related biological processes, such as jasmonic acid (JA) signaling pathway, primary metabolism, flavonoid metabolism, and programmed cell death, was altered in G1 + HBP anthers, and the accumulation of MS-associated metabolites, including fatty acids, amino acids, sugars, ATP, flavonols and reactive oxygen species (ROS), was down-regulated in G1 + HBP anthers. In summary, abnormal expression of key genes regulating anther and pollen development, altered transcription of key genes involved in MS-related metabolic pathways, and insufficient accumulation of MS-related metabolites together lead to MS in G1 + HBP. The critical genes and the metabolism pathways identified herein provide new insights into the formation mechanism of MS in citrus and candidate genes for breeding seedless citrus. [ABSTRACT FROM AUTHOR]

Soil microbial necromass carbon (C) is a crucial component of the soil organic C pool. The impact of both straw mulching treatments and years on the soil microbial necromass C accumulation remains unclear. We investigated factors driving soil microbial necromass C accumulation and its role in improving yield by analyzing the dynamic response of microbial necromass C, total organic C (TOC) and available nutrients, genes encoding carbohydrate-degrading enzymes and fruit yield of citrus under different straw types of mulching (wheat, rice, oilseed rape, no mulch) from 2019 to 2022. Annual rainfall was the main factor affecting the soil bacterial necromass C (BNC) accumulation. Straw mulching treatments were the main factor affecting the soil fungal necromass C (FNC) accumulation. Increased annual rainfall and high soil moisture levels hindered the soil microbial necromass C accumulation, especially BNC. No correlation was found between BNC and the relative abundance of genes encoding peptidoglycan (bacteria-derived biomass) degrading enzymes. Decreased relative abundance of genes encoding chitin (fungal-derived biomass) degrading enzymes, particularly GH18, favored the accumulation of FNC. Actinomycetes were the most significant contributors of the GH18 gene among microbial phyla. Moreover, oilseed rape and rice mulching treatments reduced the relative abundance of genes encoding enzymes degrading chitin. Microbial necromass C, especially BNC, was key for sustaining TOC, supplying nutrients, and enhancing citrus fruit yield. Our results provide new information for optimizing straw mulch type and application time in citrus orchards to improve soil microbial necromass accumulation. [ABSTRACT FROM AUTHOR]

Field trials were conducted in two consecutive years to evaluate the terminal residue levels, dissipation trend of cupric nonyl phenolsulfonate in citrus and soil. Analyses were carried out using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine the concentration of cupric nonyl phenolsulfonate in citrus and soil. The results showed a good linear relationship within the range of 0.01 to 5.0 mg·L−1 (R2 = 0.9999). Average recoveries were 77.70%-105.25% for cupric nonyl phenolsulfonate at the spiked levels of 0.01, 0.1,1, and 5 mg·kg−1, the relative standard deviations (RSDs) were 2.23–7.22%. Half-lives (t1/2) of cupric nonyl phenolsulfonate were 2.76–5.87 and 1.27–3.22 days in citrus and soil, respectively. The results showed that the final contents of cupric nonyl phenolsulfonate in citrus peel were the highest while that of citrus pulp were the lowest. As for soil, the final contents range from < 0.010 to 4.081 mg·kg−1. The dietary risk assessment of citrus was evaluated with risk quotients. The risk quotient values were found to be significantly < 100%, indicating that using recommended doses of cupric nonyl phenolsulfonate in citrus fruits poses risks to human health within acceptable risk levels. The results of this study contribute to the guidance of safe and reasonable use of cupric nonyl phenolsulfonate. [ABSTRACT FROM AUTHOR]

Practical Application The soluble solid content (SSC) is a primary characteristic index for evaluating the internal quality of citrus fruits. The development of rapid and nondestructive SSC detection techniques can help address the current issues of postharvest quality grading in China's citrus industry. In this study, a total of 261 experimental samples, including 70 Murcott, 91 Clementine, and 100 Navel orange, were divided into prediction and validation sets in a 7:3 ratio. After obtaining the reflection spectra and SSCs, SNV‐FOD (Standard Normal Variate—Fractional‐Order Derivative) was used to process the spectra, and the optimal band combination algorithm was introduced to select SSC‐sensitive bands. Then, the obtained optimal dual‐band combination was input into eight regression models for comparison, and the best performing models stacked ensemble models was selected. Finally, the H‐ELR (HyperOpt‐optimized ensemble learning regression) model, optimized using a Bayesian function, was applied for the effective estimation of SSC for three common citrus varieties in Guangxi, Murcott, Clementine, and Navel oranges. The results show that (1) the SNV‐FOD preprocessing method proposed in this study improved the correlation coefficient with the SSC from 0.546 to 0.836 compared to that of the original spectrum, (2) the optimal dual‐band combination (969 and 1069 nm) constructed by integrating the differential index and 1.2‐order derivative yielded the most accurate results (RPD = 2.13), and (3) the H‐ELR model, based on HyperOpt optimization, achieved good estimated performance (RPD = 2.46).This research contributes to the development of practical SSC prediction instruments with excellent universality and ease of application. [ABSTRACT FROM AUTHOR]

Citrus fruits are widely grown, processed, and distributed in more than 140 countries, with annual global production exceeding 124.3 million metric tons. This substantial consumption generates significant organic waste, accounting for approximately 50–60% of the total fruit mass, primarily in the form of peel, pulp, and seeds. Often discarded or reused as animal feed, these wastes contribute to significant environmental pollution and economic losses. Therefore, the valorization of these by-products represents an important opportunity to mitigate these challenges and improve the sustainability of the Citrus-related industry. This review highlights Citrus seed waste concerning its invaluable bioactive compounds, including fatty acids, phenolic compounds, limonoids, dietary fibers, vitamins, and carotenoids. Chemical compositions of Citrus seed biowaste differ depending on a variety of factors, such as Citrus variety, fruit maturity, environmental conditions, waste storage conditions, and extraction methods. The extraction and purification of phytochemicals from Citrus seed biowaste are one of the major procedures for valorizing waste. The two types of effective extraction methods are traditional (conventional extraction) and innovative (green extraction). Furthermore, Citrus seeds have been demonstrated to exhibit several biological activities and health-promoting properties including antioxidative, anti-inflammatory, and anti-cancer activities. Therefore, these wastes are safe and beneficial compounds used in the production of functional foods, nutraceuticals, pharmaceuticals, and cosmetics. A conclusion can be reached by emphasizing the abundance of bioactive compounds in Citrus seed wastes, which makes them an excellent opportunity for increased environmental and economic utilization. [ABSTRACT FROM AUTHOR]

The optimization of automatic solvent extraction (ASE) for obtaining grapefruit (Citrus paradisi) peel extract was conducted by Box-Behnken design under statistical experimental design approach (response surface method-RSM). The optimization is based on the D-limonene concentration since it is the major volatile compound of the grapefruit essential oil. The optimum conditions were attained with almost 7.5 g fresh grapefruit peel, and ~11 min immersion time and ~10 min washing time by application of ASE. The maximum yield was 4.91 mg D-limonene per gram fresh grapefruit peel. The reliability of the study was satisfactory (the difference between the experimental and calculated values<2%). Depending on ANOVA findings of RSM, the second power effect of mass was the most significant, followed by the second power effects of immersion time and washing time, and the linear effect of immersion time (p<0.0001). On the other hand, ~96% of the total volatile composition belong to the D-limonene depending on gas chromatography-mass spectrometry (GC-MS) measurements. Additionally, myrcene, decanal, and β-ocimene were also determined as the main flavor components in grapefruit peel extract. Moreover, the related componenens were also characterized by using nuclear magnetic resonance (1H- and 13C-NMR) techniques as well as Fourier transform infrared (FTIR) spectroscopy technology. [ABSTRACT FROM AUTHOR]

AbstractDaisy mandarin is a widely cultivated citrus species valued for its nutritional qualities and organoleptic properties, favored for both fresh consumption and processing. Optimal growth and fruit production is depend upon the availability of essential nutrients. However, soils of the central zones of Punjab are deficient in potassium which hinders the quality and production and their deficiency impairs physiological and biochemical processes, reducing fruit set, yield and quality. Potassium and calcium are vital for metabolic functions and cell wall integrity. A deficiency in any of these nutrients can results in smaller fruits, lower fruit retention and diminished organoleptic and nutritional qualities, such as reduced antioxidants content. So that, a research was conducted to evaluate the effect of different concentrations of potassium nitrate, potassium sulfate, calcium nitrate and boric acid along with paddy straw mulching on Daisy mandarin during the years 2021–22. The pooled data of this research showed that potassium nitrate (2%), is the best treatment with maximum fruit set (14.37%) and retention (72.35%) in Daisy mandarin. Additionally, the average fruit weight (207.50 g), number of fruits (162), fruit yield (33.79 kg/tree), fruit length (6.25 cm) and breadth (6.73 cm) also enhanced. Furthermore, potassium nitrate (2%) application increased the antioxidant activity (39.43%), phenolic content (230.00 mg kg−1 FW) and flavonoid content (3.69 mg RE g−1 FW). The findings suggest that application of potassium nitrate presents a promising strategy for enhancing fruit set, yield and quality of Daisy mandarin, providing valuable insights for improved cultivation practices. [ABSTRACT FROM AUTHOR]

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Drought stress poses increasingly serious threats to agricultural production in the era of global climate change. Arbuscular mycorrhizal (AM) fungi are well-recognized biostimulants promoting plant tolerance to drought stress. Lipids are indispensable for AM fungal colonization, however, the involvement of lipid metabolism in the drought tolerance conferred by AM fungi is largely unknown. In this study, we inoculated Poncirus trifoliata (L.) with Rhizophagus irregularis DAOM197198 under no drought stress, medium drought stress and severe drought stress, with non-inoculation under respective treatments as control. Results indicated that AM fungal inoculation significantly promoted the drought tolerance of P. trifoliata (L.), with the effect size decreasing along with drought severity. Moreover, the effect size was significantly related to arbuscule abundance. Fatty acid profiling showed that the arbuscule abundance was determined by the AM-specific phospholipids (PLs), whose biosynthesis and delivery were inhibited by drought stress as revealed by qRT-PCR of FatM, RAM1 and STR/STR2. More interestingly, AM fungal inoculation increased the lipid allocation to total PLs and the unsaturation rate of total neutral lipids (NLs), probably indicating the involvement of non-AM-specific lipids in the increased drought tolerance. Taken together, our results demonstrate that lipid metabolism in AM mediates the increased drought tolerance conferred by AM fungal inoculation, with AM-specific and non-AM-specific lipids functioning therein in different ways. [ABSTRACT FROM AUTHOR]

This study investigated the phenology and population dynamics of potential insect vectors of Xylella fastidiosa Wells et al. and other Auchenorrhyncha species in olive and citrus groves of Chania province, Crete, Greece. Although X. fastidiosa has not been reported in Greece, its introduction could cause serious diseases in many crops, including olives and citrus. Olive groves of Olea europaea L. 'Koroneiki' were sampled systematically using sweep net and Malaise traps over 24 months. One citrus grove was sampled for one year using a Malaise trap. Sweep net samples were taken from the herbaceous cover, tree canopy, and field borders of olive groves. Auchenorrhyncha were more abundant on the herbaceous cover compared to the canopy and field margins. Aphrophoridae species were mostly found on the herbaceous cover and in low numbers during fall (October–December) and spring (April–May). Cicadellidae species, such as Euscelis spp., were frequently found on the herbaceous cover of both olive and citrus groves. One Aphrophoridae and several Cicadellidae species were recorded in the citrus grove. Altitude was found to influence the population abundance of some Auchenorrhyncha species in olive groves. These results provide information for effective integrated management of insect vectors and their vector-borne pathogens. [ABSTRACT FROM AUTHOR]

Simple Summary: Citrus (Citrus spp.) is the world's largest fruit crop, both in terms of cultivation area and production. In recent years, the citrus industry in countries such as China, Brazil, and the United States has suffered significant damage due to the increasing severity of citrus diseases, such as Citrus Huanglongbing (HLB). Plant nucleotide-binding leucine-rich repeat (NLR) genes play a critical role in the plant immune system by helping plants resist pathogen infections. A thorough understanding of the diversity and evolution of citrus NLR genes is of great significance for the development of disease-resistant cultivars. In this study, we systematically identified 1585 NLR genes across 10 citrus genomes and conducted an in-depth analysis of their origins and evolutionary processes. NLR genes are crucial components of the effector-triggered immunity (ETI) system, responsible for recognizing pathogens and initiating immune responses. Although NLR genes in many plant species have been extensively studied, the diversity of NLR genes in citrus remains largely unknown. Our analysis revealed significant variations in the copy numbers of NLR genes among these species. Gene duplication and recombination were identified as the major driving forces behind this diversity. Additionally, horizontal gene transfer (HGT) emerged as the principal mechanism responsible for the increase in NLR gene copy number in A. buxifolia. The citrus NLR genes were classified into four categories: TIR-NBS-LRR (TNL), CC-NBS-LRR (CNL), RPW8-NBS-LRR (RNL), and NL. Our findings indicate that TNL, RNL, and CNL genes originated from NL genes through the acquisition of TIR and RPW8 domains, along with CC motifs, followed by the random loss of corresponding domains. Phylogenetic analysis suggested that citrus NLR genes originated alongside the species and underwent adaptive evolution, potentially playing crucial roles in the global colonization of citrus. This study provides important insights into the diversity of citrus NLR genes and serves as a foundational dataset for future research aimed at breeding disease-resistant citrus varieties. [ABSTRACT FROM AUTHOR]

Simple Summary: Tephritid fruit flies are major economic pests that impact fruit production and impede international trade. The type of host fruit influences the ability of a fruit fly to complete their life cycle. International regulatory standards that define host status categorize fruits as a natural host, a conditional host, or a nonhost. For those fruits that are natural or conditional hosts, the infestation rate can vary across a spectrum ranging from highly attractive well-suited hosts supporting large numbers of fruit flies to very poor hosts supporting low numbers. Persian lime, Citrus x latifolia, is a new crop in Hawai'i, and no information existed on its susceptibility to Hawai'i's tephritid fruit fly pests. Host status testing was conducted using no-choice laboratory and field cage tests as well as field collection of fruit. Mediterranean fruit fly and Oriental fruit fly oviposited and developed in artificially damaged (punctured) limes in cage tests but did not infest undamaged commercial quality fruit, suggesting Persian limes should be considered a conditional host. Field-collected and processed export-quality Persian limes (total of 45,954 fruit) were not naturally infested by Mediterranean fruit fly and Oriental fruit fly. In regulations, risk managers may use the term conditional nonhost to describe regulated articles, like Persian limes from Hawai'i, which do not pose a pest risk. We investigated the host status of harvest-ready green Persian lime, Citrus x latifolia Tan. (Rutaceae), to Oriental fruit fly (Bactrocera dorsalis [Hendel]) and Mediterranean fruit fly (Ceratitis capitata [Wiedemann]) (Diptera: Tephritidae) using laboratory and field studies. In forced-infestation small cage exposures (using 25 × 25 × 25 cm screened cages with 50 gravid females) and large olfactometer cage tests (using 2.9 × 2.9 × 2.5 m walk-in screened cages with 100 gravid females), punctured limes were infested by Oriental fruit fly and Mediterranean fruit fly at low rates compared to papaya controls, whereas undamaged intact fruit was not infested. Field collection and packing of 45,958 commercial export-grade fruit and subsequent incubation to look for natural infestation resulted in no emergence of fruit flies. Forced infestation studies in the field using sleeve cages to enclose fruit with a high density of fruit flies (50 gravid females) on the tree also showed no infestation. Commercial export-grade Persian lime fruit should be considered a conditional nonhost for Oriental fruit fly and Mediterranean fruit fly. [ABSTRACT FROM AUTHOR]

Purpose: High consumption of fruits and vegetables decrease the risk of bladder cancer (BC). The evidence of specific fruits and vegetables and the BC risk is still limited. Methods: Fruit and vegetable consumptions in relation to BC risk was examined by pooling individual participant data from case–control studies. Unconditional logistic regression was used to estimate study-specific odds ratio's (ORs) with 95% confidence intervals (CIs) and combined using a random-effects model for intakes of total fruits, total vegetables, and subgroups of fruits and vegetables. Results: A total of 11 case–control studies were included, comprising 5637 BC cases and 10,504 controls. Overall, participants with the highest intakes versus the lowest intakes of fruits in total (OR 0.79; 95% CI 0.68–0.91), citrus fruits (OR 0.81; 95% CI 0.65–0.98), pome fruits (OR 0.76; 95% CI 0.65–0.87), and tropical fruits (OR 0.84; 95% CI 0.73–0.94) reduced the BC risk. Greater consumption of vegetables in total, and specifically shoot vegetables, was associated with decreased BC risk (OR 0.82; 95% CI 0.68–0.96 and OR 0.87; 95% CI 0.78–0.96, respectively). Substantial heterogeneity was observed for the associations between citrus fruits and total vegetables and BC risk. Conclusion: This comprehensive study provides compelling evidence that the consumption of fruits overall, citrus fruits, pome fruits and tropical fruits reduce the BC risk. Besides, evidence was found for an inverse association between total vegetables and shoot vegetables intake. [ABSTRACT FROM AUTHOR]

Extracellular enzymes produced by fungi can serve as a screening tool for entomopathogen candidates. Enzyme secretion ability is important in determining the virulence level of an entomopathogenic fungus. This study aims to see the potential of fungal isolates through chitinolytic, lipolytic, and proteolytic activities of five entomopathogenic fungal isolated from Bactrocera sp. imago from citrus plants. The research was carried out at the Microbiology Laboratory of the Department of Biology at the University of Lampung. Enzymatic activity is known through the method of observing the clear zone formed on agar media. Quantitative tests based on the calculation of enzymatic index values showed that Nigrospora sp. (IB1) had lipolytic activity, Penicillium sp. 2 (IB5) isolates had chitinolytic, lipolytic, and proteolytic activities. The isolates of Penicillium sp. 1 (IB2), Phytopthora sp. (IB3), and Gliocladium sp. (IB4) did not show the activity of the three enzymes. [ABSTRACT FROM AUTHOR]

Bujangseta is a technology used throughout the year to produce citrus fruits. This technology has economically succeeded in increasing the income of citrus farmers by 23.5%. Sustainable management of bujangseta technology is neede, one of which is maintaining the sustainability of the agroecosystem. A stable agroecosystem ensures the availability of ecosystem services through nutrient cycling and the natural control of pest and disease populations. The stability of agroecosystems is coherent with the high biodiversity of arthropods. This study aims to evaluate the effect of applying the citrus plant bujangseta in Karangwidoro village and Krajan village, Dau District, Malang Regency, East Java, from June to December 2022. The two application methods were light trapping (lighttrap) and pit trap (pitfall glass), and the results were analyzed using a t-test. The diversity index, species richness index, species evenness index, and dominance index were calculated. The results showed that the detrivores of the Collembola group dominated the diversity of arthropods, the primary pest of the Diaphorina citri, and the predatory arthropods of Paederus sp. and Braconidae. Diversity and community structure of arthopods indicated there at significant differences in diversity, dominance, evenness, and species richness in those two locations. Bujangseta in the Krajan has a higher community structure compared to the Karangwidoro, showing that the ecosystem at the Krajan location is better preserved. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the efficacy of citrus peel phenolic compounds extracted using carboxylated multi -walled carbon nanotubes (MWCNT –COOH) with common synthetic antioxidants [butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT)] in stabilizing sunflower oil (SO) during frying (180 ± 5 °C, 24 h). To evaluate the antioxidant activity of these compounds, total phenolic, and flavonoid contents, reducing power, ABTS scavenging activity, β -carotene bleaching ability, and 1, 1 -diphenyl - 2 - picrylhydrazyl (DPPH) radical scavenging activity were measured. Extracts were combined at various concentrations (100 -1000 ppm) with SO, and both synthetic antioxidants were standardized at 200 ppm. Thermal -oxidative stability was investigated by assessing the change in peroxide value (PV), color, free fatty acid (FFA) content, conjugated diene value (CDV), and thiobarbituric acid (TBA). Bitter orange peel extract (BPE) displayed a higher content of phenolic compounds and antioxidant activity. At 1000 ppm, it showed a lower FFA content, PV, TBA, and CDV. It can be used as an alternative to synthetic antioxidants. As a result, citrus peel phenolic compounds extracted with MWCNT –COOH can be used as preservatives in frying oils. [ABSTRACT FROM AUTHOR]

Citriculture faces challenges from abiotic and biotic stresses, in which biotic stresses like diseases, insects and nematodes, abiotic stresses like salinity, drought, and temperature fluctuations. The complex interactions between several biotic and abiotic stressors and citrus. To understand, how salt affects citrus fruit production and quality and how citrus rootstocks respond morphologically and biochemically to different stress conditions like salinity. Further, it explores the mechanisms of resistance in citrus rootstocks by studying their morphological and biochemical responses to heat, cold, drought stress and combination stresses. Citrus greening (Huanglongbing), citrus tristeza virus (CTV), citrus variegated chlorosis (CVC), insects, diseases and nematodes are some of the main issues that are highlighted in terms of biotic challenges. Rootstocks play a crucial role in mitigating these stresses, influencing tree vigor, yield, and overall crop health. Strategies in rootstock development are explored for enhanced crop resilience. Citrus rootstocks respond differently to these biotic stresses, and their reactions and discuss effective management options. Additionally, the selection of rootstock and integrated management measures for sustainable citrus productivity. Methods of managing nematodes, Phytophthora infections, and citrus canker. Citrus producers and researchers can have more information about the biotic and abiotic challenges in citrus production from this comprehensive collection of facts which paves the way for the development of environmentally friendly methods that improve citrus yield by reducing the impact of stresses. [ABSTRACT FROM AUTHOR]

Citrus is one of the world's most important and widely produced fruit crops, with over a 100 million metric tons harvested from nearly 10 million hectares in 2023. Challenges in crop maintenance, production, and fruit quality necessitate developing new traits through Agrobacterium-mediated genetic transformation. While a few Agrobacterium strains (EHA105, GV3101, LBA4404) are known to transform citrus, many wild strains remain untested. We screened forty-one wild-type Agrobacterium strains isolated from various woody species and identified five capable of DNA transfer into citrus cells. Strain 1D1416 demonstrated the highest transient transformation frequency in Carrizo epicotyl explants (88%), outperforming the control EHA105 (84%) with comparable shoot regeneration rates (32% and 42%, respectively). Notably, 1D1416 exhibited no overgrowth and had the lowest necrosis and mortality rates in transformed tissues. It efficiently transferred the DsRed gene and induced galls in mature tissues of Mexican lime (70%), lemon (48%), Washington navel orange (25%), and clementine (6%). Genome sequencing of 1D1416 allowed for the disarming of the native T-DNA and addition of GAANTRY technology. This novel strain, combined with an optimized transformation procedure, make it a valuable tool for advancing citrus transformation. [ABSTRACT FROM AUTHOR]

'Redson' is a new triploid, red-fleshed pomelo x grapefruit hybrid. The goal of this study was to examine the effects of rainfall, harvest time, tree age, and yield on the postharvest storage performance of 'Redson' fruit. During 2022/23, two postharvest storage trials were conducted with early- and late-harvested fruit. The fruit from the early harvest retained good quality for up to 16 weeks of storage at 7.5 °C plus 1 week at 22 °C, whereas the late-harvested fruit suffered from a high decay incidence. During 2023/24, we expanded the postharvest trials to nine different fruit sets harvested from early season (late October) until the end of the season (January). Fruit quality was examined under the same storage conditions after 6 and 16 weeks, and the results indicated that early- and mid-season fruit retained good quality with minimal decay incidence even after prolonged storage for 16 weeks, whereas the late-season fruit suffered from significant decay incidences of 17–22% and a decline in flavor acceptability. Further analysis revealed strong and significant correlations between various rainfall parameters and harvest time and decay incidences. Overall, early-harvested fruit during the autumn had a superior postharvest storage performance, whereas late-harvested fruit during the rainy winter suffered from decay development. [ABSTRACT FROM AUTHOR]

For citrus trees cultivated by dwarf dense planting, the fruits are randomly distributed in space, which poses difficulties for mechanized picking. To improve picking efficiency, a citrus picking system based on dual robot collaboration is designed and a global scanning picking scheme that scans the entire fruit tree to achieve orderly fruit picking is proposed in this research. The dual‐robot calibration with the iterative method and closed‐form method is completed in the research. The picking problem is attributed to the single traveling salesman problem, and the trajectory planning and the picking task are completed with genetic algorithm in the research. The picking experiments are designed in the research. As a result, in the picking experiments, the average time for planning the picking sequence of citrus was 0.1184 s, the longest time is 0.1560 s. In each group of citrus picking experiments, the total picking time averaged 158.9 s, the longest group took 170 s, the picking success rate is 82%. The picking results show that the built dual‐machine system can effectively complete the picking task and meet the real‐time requirement of picking. The proposed dual‐robot picking system can provide a reference for the establishment of other picking robot system. [ABSTRACT FROM AUTHOR]

Blue mold disease, caused by Penicillium italicum (P. italicum), presents a significant challenge to orange fruits (Citrus sinensis L.) and other citrus crops globally. Biological control, particularly Trichoderma species, offers a promising alternative to synthetic fungicides. Therefore, this study aimed to isolate, identify, and evaluate the antagonistic activities of two Trichoderma isolates against P. italicum. These isolates were molecularly identified and assigned accession numbers PP002254 and PP002272, respectively. Both isolates demonstrated significant antifungal activity in dual culture assays. Moreover, the culture filtrates (CFs) of Trichoderma longibrachiatum PP002254 and Trichoderma harzianum PP002272 suppressed the mycelial growth of P. italicum by 77.22% and 71.66%, respectively. Additionally, CFs reduced the severity of blue mold on orange fruits by 26.85% and 53.81%, compared to 100% in the control group. Scanning electron microscopy revealed that treated P. italicum hyphae were shrunken and disfigured. Enzyme activities (catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase) in treated oranges increased, along with total soluble phenolics and flavonoids. Conversely, malondialdehyde (MDA) levels decreased in treated fruits. These findings suggest that T. longibrachiatum PP002254 and T. harzianum PP002272 could be effective biocontrol agents for managing blue mold and other citrus postharvest diseases. [ABSTRACT FROM AUTHOR]

The effect of N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) on fruit splitting of 'Murcott' tangor fruit (Citrus reticulate × Citrus sinensis) was analyzed throughout two successive seasons during 2020 and 2021. 'Murcott' trees were treated with various concentrations of CPPU, 1.0, 5.0, and 10.0 mg·L−1, which significantly reduced the splitting of fruit compared with the control fruit and the gibberellic acid (GA3)-treated fruit (20.0 mg·L−1). The fruit treated with 5.0 mg·L−1 CPPU exhibited higher levels of fruit weight, longitudinal diameter, transverse diameter, peel strength, and peel thickness compared to the control fruit. In addition, the tree sprayed with 5.0 mg·L−1 CPPU had the greatest number of cellular layers and cells at the stylar end calculated in fruit. However, there were no other fruit quality characteristics significantly affected by CPPU and GA3 treatments. [ABSTRACT FROM AUTHOR]

Citrate is a major determinant of fruit flavor quality. Currently, citrus species and/or varieties with significant alterations in citrate level have greatly advanced the molecular basis of citrate accumulation in fruit. However, in-depth dissections of the molecular mechanism specific to citrate accumulation are still limited due to the lack of mutants, especially within one single variety. In this study, a fresh-sweet 'Shatangju' mutant (Citrus reticulata cv.) was obtained during a survey of citrus resources in Guangdong, China, and the phenotype, fruit morphology, and primary flavor profiles were comparatively analyzed. Unlike the wild-type 'Shatangju' (WT), the mutant (MT) material exhibited a dwarfed and multi-branched tree shape, delayed flowering and fruit ripening at maturity, a prolonged fruit tree-retention time, and a decreased single fruit weight at maturity. Dynamic measurement of the metabolite levels further suggested that the contents and fluctuation patterns of vitamin C, malate, quinate, and oxalate showed no obvious difference between MT and MT fruits, while the citrate level in MT fruits significantly decreased over various developmental stages, ranging from 0.356 to 1.91 mg g−1 FW. In addition, the accumulation patterns of the major soluble sugars (sucrose, fructose, and glucose), as well as the sugar/acid ratio, were also altered in MT fruits during development. Taken together, this study provides a novel acid-free 'Shatangju' mutant, which can serve as a powerful tool for the research of fruit flavor quality, especially for the comprehensive understanding of the molecular mechanism of citrate accumulation in fruits. [ABSTRACT FROM AUTHOR]

The Defective in Induced Resistance 1 (DIR1) gene, a member of the lipid transferase proteins (LTPs), plays a crucial role in plant defense against pathogens. While previous transcriptomic studies have highlighted the significant expression of citrus LTPs during biotic stress, functional annotations of LTPs in the Citrus genera remain limited. In this study, we cloned the Murraya paniculata DIR1 (MpDIR1(t)) gene and overexpressed it in Arabidopsis thaliana to evaluate its stress response mechanisms against biotic stress. The transgenic Arabidopsis lines showed fewer disease symptoms in response to Pseudomonas syringae (Pst DC3000) compared to wild-type Arabidopsis. Defense and pathogenesis-responsive genes such as PR1, PR4, PR5, and WRKY12 were significantly induced, showing a 2- to 12-fold increase in all transgenic lines compared to the wild type. In addition, the Pst DC3000-infected transgenic Arabidopsis lines demonstrated elevated levels of flavonoids and salicylic acid (SA), along with higher expression of SA-related genes, compared to the wild type. Moreover, all transgenic lines possessed lower reactive oxygen species levels and higher activity of antioxidant defense enzymes such as superoxide dismutase, peroxidase, and catalase under Pst DC3000 stress compared to the wild type. The up-regulation of defense genes, activation of the SA pathway, accumulation of flavonoids, and reinforcement of antioxidant defense mechanisms in transgenic Arabidopsis lines in response to Pst DC3000 underscore the critical role of MpDIR1(t) in fortifying plant immunity. Thus, MpDIR1(t) constitutes a promising candidate gene for improving bacterial disease resistance in commercial citrus cultivars. [ABSTRACT FROM AUTHOR]

Citrus fruits are among the most produced and traded agricultural products worldwide, with significant economic and social importance. Despite their importance in the European Union, Middle East, and Africa, the existing literature is limited. Several studies have reviewed different aspects of general agri-food supply chains, but a product-based literature review on citrus supply chains has not been conducted. This paper provides a comprehensive review of the citrus supply chain in these regions, identifying the key research topics, methodologies, and supply chain echelons addressed in the literature. The study employed a systematic review, real-world case studies, and supply chain stakeholders' interviews. This multi-faceted approach allows researchers to highlight research gaps, map a complete citrus supply chain, and provide a detailed material flow and sustainability-oriented overview of potential inputs and outputs at different stages. By incorporating real-world case studies and stakeholder interviews, this paper offers a nuanced and practical perspective on the operational and sustainability challenges unique to the citrus supply chain. This study serves as a guide for future research and enables practitioners to pinpoint areas and strategies for operational improvement across the supply chain. [ABSTRACT FROM AUTHOR]

The complexity of citrus phylogeny and taxonomy, influenced by polyembryony, genetic diversity, and extended generation cycles, necessitates assessing genetic relationships for improved production and disease resilience. DNA polymorphism markers are pivotal in genotyping and resolving phenotypic varietal ambiguities through accurate and objective genetic relatedness and distinctiveness assessments. In this study, 27 accessions of kagzi and ornamental lime were evaluated at morphological (based on IPGRI citrus descriptor), biochemical, and molecular levels using DNA-based markers, namely, random amplified polymorphic DNA (RAPD), start codon targeted (SCoT) polymorphism, and simple sequence repeats (SSR). Morphological analysis unveiled significant variation in leaf lamina attachment, shape, margins, fruit characteristics, and texture across all parameters. Biochemical research noted minimal differences, with total soluble solids (TSS) ranging from 5.7° to 8.0° Brix and titratable acidity (TA) from 0.36 to 0.50%. Notably, ornamental lime accessions exhibited higher TSS:TA ratios of 16.00. Molecular markers (RAPD, SCoT, and SSR) corroborated these findings, yielding 115, 74, and 64 amplicons, respectively, with polymorphic percentages varying from 33.33 to 100%. Polymorphic information content ranged from 0.20 to 0.90 for RAPD, 0.41 to 0.99 for SCoT, and 0.07 to 0.67 for SSR markers. Analysis of molecular variance (AMOVA) substantiated significant genetic differences among the kagzi and ornamental lime accessions (RAPD PhiPT = 0.267, SCoT PhiPT = 0.351, SSR PhiPT = 0.107). Furthermore, STRUCTURE software 2.3.4 revealed a ΔK value of two (K = 2), indicating two distinct genetic pools within the accessions, possibly attributable to bud mutations generating varying morphological traits within the same plant. Molecular marker-based germplasm characterization can mitigate confusion linked to morphological characteristics and multiple cultivar registrations. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the effects of extracts of different citrus fruits peel on the oxidation of canola oil during 5-day accelerated condition and compare the antioxidant activity of the peel extracts from citrus fruits (cultivated in north and south of Iran).The citrus peel ethanolic extracts prepared by ultrasound-assisted technique (150 w, 40 ◦C, and 30 min) showed significantly higher extraction efficiency and phenolic compounds in comparison to the extracts produced through the conventional extraction method. Southern Bitter orange peels had the highest amount of TPC (1.78 mg GAE/g) followed by northern bitter orange (1.46 mg GAE/g), southern lemon (1.25 mg GAE/g), northern lemon (1.02 mg GAE/g), southern orange (1.32 mg GAE/g), and northern orange (1.10 mg GAE/g)peels. TPCs of citrus peels of the south of Iran were higher than TPCs of north-cultivated citrus fruits. The oxidative stability and the free radical scavenging(DPPH) activity of southern bitter orange peel extract was the highest among the other treatments followed by northern bitter orange, southern orange, northern orange, southern lemon, and northern lemon extracts. According to the results, the peel extracts containing phenolic compounds as natural antioxidants have the potential of reacting with the free radicals produced from lipid oxidation. [ABSTRACT FROM AUTHOR]

This study evaluated the relationship between Zn in citrus leaves and some easily available soil properties using artificial neural network (ANN), gene expression programming (GEP), and stepwise regression methods. The data of 40 soil samples collected at the South of Kerman region (Iran) were used. Different combinations of input parameters, including soil texture, pH, organic carbon (OC), total neutralizing value (TNV), electrical conductivity (EC), and soil available P (Polsen), were considered. The coefficient of determination (R2), the normalized root means square error (NRMSE), mean absolute error (MAE), and Nash–Sutcliffe efficiency (NS) were used to evaluate the accuracy of the models. The results showed that the models with whole input parameters offered the lowest NRMSE and the highest R2. The ANN model with four input variables showed that 77% of the Zn variation in leaves could be elucidated by the explicit soil parameters, including clay, silt, OC, and Polsen. These results showed that the ANN model with six neurons in the hidden layer had the best performance in modeling Zn uptake. However, since the main goal of this research was to improve the models based on easily measurable variables, the GEP model with three input variables, including silt, OC, and Polsen, was found to be beneficial in estimating 71% of Zn-leaves variability. [ABSTRACT FROM AUTHOR]

Given the ease of propagating fruit tree species through cloning, the economic viability of their breeding programs hinges on protecting breeders' rights. This necessitates the development of highly accurate DNA markers for cultivar identification. Here, we present a methodology for the rapid design of cleaved amplified polymorphic sequence (CAPS) markers to discriminate newly bred Japanese citrus cultivars from genetically related cultivars. We first compared the performance of ddRAD-seq and MIG-seq in citrus germplasm. The ddRAD-seq libraries generated using EcoRI and HindIII restriction enzymes yielded the highest number of polymorphisms. Subsequently, ddRAD-seq with EcoRI and HindIII was employed to analyze 29 citrus cultivars and thus identify 331,801 genome-wide polymorphisms. A semi-automated bioinformatics pipeline was then utilized to identify candidate CAPS markers, resulting in the discovery of 14,072 potential markers. Of these candidates, 52 were chosen for validation based on their recognition by the PstI restriction enzyme. This evaluation resulted in the development of 11 highly discriminative CAPS markers. Remarkably, a combination of only six such markers was sufficient to differentiate newly bred cultivars from their genetically related parents. The single restriction enzyme employed for these markers facilitates straightforward multiplexing. Finally, a combination of one multiplex marker testing two loci and four singleplex markers was successfully selected that completely discriminated the cultivars other than the bud sports used in this study. The pipeline established here extends beyond citrus and has the potential to simplify marker development and cultivar protection in various plant species. [ABSTRACT FROM AUTHOR]

CITRUS is one of the most important fruit crops grown in the worldwide, especially in Mediterranean countries. Deficit irrigation (DI) is a proposed strategy many years ago to overcome the scarcity of water, especially in arid and semiarid regions. The vegetative growth, enzymatic activities, proline and phenolic content, fruit yield and quality in response to deficit irrigation levels (T1 (irrigation every 15 days as a control), T2 (irrigation every 20 days), T3 (irrigation every 25 days), and T4 (irrigation every 30 days), were evaluated. The results showed that the P, K, proline, phenols, vitamin C, SSC contents, and catalase and peroxidase activities were increased by T2 and T3. While the N content, fruit yield, weight, peel thickness, juice volume, and transpiration rate were increased by T1 and T2 compared to T3 and T4. The fruit yield, weight, and physical properties were not negatively affected by light and medium deficit irrigation (T2 and T3), which positively affected enzymatic activities, proline and phenol contents, and chemical fruit properties (SSC and Vitamin C). [ABSTRACT FROM AUTHOR]

Mastication trait of citrus significantly influences the fruit's overall quality and consumer preference. The accumulation of cellulose in fruits significantly impacts the mastication trait of citrus fruits, and the glycoside hydrolase 9 (GH9) family plays a crucial role in cellulose metabolism. In this study, we successfully identified 32 GH9 genes from the Citrus sinensis genome and subsequently conducted detailed bioinformatics analyses of the GH9 family. Additionally, we profiled the spatiotemporal expression patterns of CsGH9 genes across four distinct fruit tissue types and six crucial developmental stages of citrus fruits, leveraging transcriptome data. Parallel to this, we undertook a comparative analysis of transcriptome profiles and cellulose content among diverse fruit tissues spanning six developmental stages. Furthermore, to identify the pivotal genes involved in cellulose metabolism within the GH9 family during fruit maturity, we employed correlation analysis between cellulose content and gene expression in varying tissues across diverse citrus varieties. This analysis highlighted key genes such as CsGH9A2/6 and CsGH9B12/13/14/22. Collectively, this study provides an in-depth analysis of the GH9 gene family in citrus and offers novel molecular insights into the underlying mechanisms governing the mastication trait formation in citrus fruits. [ABSTRACT FROM AUTHOR]

CRISPR/Cas9-mediated gene editing requires high efficiency to be routinely implemented, especially in species which are laborious and slow to transform. This requirement intensifies further when targeting multiple genes simultaneously, which is required for genetic screening or more complex genome engineering. Species in the Citrus genus fall into this category. Here we describe a series of experiments with the collective aim of improving multiplex gene editing in the Carrizo citrange cultivar using tRNA-based sgRNA arrays. We evaluate a range of promoters for their efficacy in such experiments and achieve significant improvements by optimizing the expression of both the Cas9 endonuclease and the sgRNA array. In the case of the former we find the UBQ10 or RPS5a promoters from Arabidopsis driving the zCas9i endonuclease variant useful for achieving high levels of editing. The choice of promoter expressing the sgRNA array also had a large impact on gene editing efficiency across multiple targets. In this respect Pol III promoters perform especially well, but we also demonstrate that the UBQ10 and ES8Z promoters from Arabidopsis are robust alternatives. Ultimately, this study provides a quantitative insight into CRISPR/Cas9 vector design that has practical application in the simultaneous editing of multiple genes in Citrus, and potentially other eudicot plant species. [ABSTRACT FROM AUTHOR]

Introduction: Citrus hybrids with Poncirus trifoliata L. Raf. introgression have gained interest due to their tolerance to Huanglongbing (HLB), a devastating disease for Florida citrus agriculture. While these hybrids inherit disease tolerance from P. trifoliata, they sometimes also suffer from undesirable off-flavors. Methods: A selection of thirteen genotypes were harvested over the 2020-2021 and 2021-2022 seasons. Their juices were evaluated by a trained sensory panel and were comprehensively analyzed for their chemical makeup, including soluble solids content (SSC), titratable acidity (TA), volatiles, flavonoids and limonoids. Results & discussion: Overall, along with the commercial orange cultivars 'Valencia' and 'Hamlin', the HLB-tolerant Poncirus hybrid 'US SunDragon,' and the mandarin hybrids Sugar Belle¬, FF-5-51-2, and 'US Superna' had positive citrus flavor quality. Esters, some sesquiterpenes, along with flavonoids, eriocitrin and quercetin-3-(3R-glucosylrutinoside), were positively correlated with orange flavor while b-ionone and eucalyptol were highly abundant in the mandarins. The flavonoid linarin, was more abundant in Poncirus hybrids with off-flavors than in the Poncirus hybrid 'US SunDragon', having high orange flavor. Two mandarin hybrids, FF-5-6-36 and FTP-6-32-67, were not bitter at harvest, but the juice exhibited delayed bitterness after storage at -20°C, which was associated with significant increases of limonin, nomilin, naringenin, and prunin. Interestingly, during freezer storage, a newly identified flavonoid in citrus, tricin-C-hexoside, increased dramatically across all of the genotypes. The identification of diseasetolerant hybrids with satisfactory flavor quality at juicing as well as after storage where delayed bitterness may develop, has great significance for future breeding efforts for fresh fruit or for use in stand-alone juice/juice blends. [ABSTRACT FROM AUTHOR]