Citrus Varieties Research Articles

An engineered citrus tristeza virus (T36CA)-based vector induces gene-specific RNA silencing and is graft transmissible to commercial citrus varieties.

A protein-expressing citrus tristeza virus (CTV)-based vector construct, pT36CA-V1.3, obtained from a California isolate of the T36 strain (T36CA), was retooled into a virus induced gene silencing (VIGS) system intended for use with studies of California citrus. VIGS constructs engineered with a truncated Citrus macrophylla (Cm) PHYTOENE DESATURASE (PDS) gene sequence in the sense or anti-sense orientation worked equally well to silence the endogenous CmPDS gene. In a parallel effort to optimize vector performance, two non-synonymous nucleotides in open reading frame 1a of pT36CA-V1.3 were replaced with those conserved in the reference sequences from the T36CA cDNA library. The resulting viruses, T36CA-V1.4 (with one amino acid modification: D760N) and T36CA-V1.5 (with two amino acid modifications: D760N and P1174L), along with T36CA-V1.3 were individually propagated in Nicotiana benthamiana and C. macrophylla plants. Enzyme-linked immunosorbent assay (ELISA) measurements of extracts of the newly emerged leaves suggested that all three viruses accumulated to similar levels in N. benthamiana plants at 5 week-post-inoculation. ELISA values of T36CA-V1.4- and -V1.5-infected C. macrophylla samples were significantly higher than that of T36CA-V1.3-infected samples within an 8 to 12 month-post-inoculation (mpi) window, suggesting a higher accumulation of T36CA-V1.4 and -V1.5 than T36CA-V1.3. However, at 36 mpi, the ELISA values suggested that all three viruses accumulated to similar levels. When C. macrophylla plants infected with each of the three viruses were grafted to commercial citrus varieties, a limited number of receptor plants became infected, demonstrating a weak but nonetheless (the first) successful delivery of T36CA to California-grown commercial citrus.

Extraction, Characterization, and Biological Activity of Volatile and Non-volatile Components of Grapefruit

Grapefruit (Citrus X paradisi) is among the biggest and most popular fruit crops grown for profit, worldwide. It is not only economically essential but also remains a popular human dietary ingredient. There are numerous varieties of citrus, all coming with vibrant colors. Both processed and fresh forms are consumed. Half of the fruit, including seeds, peels, and pith remnants are inedible and wasted after processing. Pectin, essential oils, citric acid, flavonoids, and other significant phytochemicals derived from citrus are currently widely studied in food, industrial, and synthetic chemistry. This study examines the properties of flavonoids derived from citrus leaves, their extraction process, and their usage with respect to potential health advantages. Using GC-MS/MS, the flavonoids content of grapefruit leaf extracts was determined. It was found that the primary flavonoid present in grapefruit pulp, oven-dried leaves, and fresh leaves was isonaringin. In new experiments, fresh and dried leaves of grapefruit (dried at 45°C) showed a potent cytoprotective effect on neuroblastomas SH-SY5Y. According to the data, bioactive flavonoids are naturally found in fruit leaves that can be used as remedy in many therapeutic and antibacterial activities.

Mitigating citrus fruit cracking: the efficacy of chelated calcium or silicon foliar fertilizers in 'Okitsu no. 58' citrus fruit.

The 'Okitsu No. 58' citrus variety is highly prone to fruit cracking, which jeopardizes yield and results in economic losses. In this study, we investigated the impacts of spraying 5 distinct concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 g/L) of chelated calcium (Ca) or silicon (Si) fertilizers at the young fruit stage (60-90 days after flowering, DAF) on fruit cracking and quality in the citrus variety 'Okitsu No. 58'. The results showed either Ca or Si fertilizer treatments reduced fruit cracking. We found that all Ca and partial Si treatments (0.4 and 0.5 g/L) significantly promoted the accumulation of Ca content in the peel. Notably, Ca or Si treatments significantly reduced polygalacturonase (PG) activity and inhibited the production of water-soluble pectin (WSP) in the peel. Additionally, Ca or Si treatments elevated the superoxide dismutase (SOD) activity and decreased the malondialdehyde (MDA) content of the peels. Changes in these parameters likely contributed to strengthening the durability of peel cell wall constituents, thus enhancing the fruit's resistance to fruit cracking. Overall, except for the C3 (0.3 g/L of Ca), Ca or Si fertilizers contributed to fruit conventional quality, mainly in terms of higher soluble sugars (SS) and SS/TA (titratable acid). Therefore, our findings will provide a reference for the prevention and control of citrus fruit cracking and the development of new fertilizers.

Establishment of breeding research of the genus Citrus in the subtropics of the Russian Black Sea coast

The article briefly describes the history behind the creation of the Sochi Agricultural and Horticultural Experimental Station (now known as the Federal Research Center ‘the Subtropical Scientific Centre of the Russian Academy of Sciences’), as well as the techniques and methods of breeding research to create new varieties of the genus Citrus. A brief biography of the breeder Fyodor Zorin (1904-1967) is presented, as well as the varieties of citrus crops created by him. The article tells the story behind the Friendship Tree, its importance in promoting the ideas of peace and friendship of peoples, and how it became a unique botanical garden.

Cytological and metabolomic analysis of Citrus fruit to elucidate puffing disorder

Puffiness, a physiological disorder commonly observed during the ripening and post-harvest processes of fruits in Citrus reticulata, significantly affects the quality and shelf-life of citrus fruits. The complex array of factors contributing to puffiness has obscured the current understanding of its mechanistic basis. This study examined the puffing index (PI) of 12 citrus varieties at full ripeness, focusing on the albedo layer as a crucial tissue, and investigated the correlation between cellular structural characteristics, key primary metabolites and PI. The findings revealed that the cell gap difference and the number of lipid droplets were closely linked to PI. Chlorogenic acid, Ferulic acid, D-Galacturonic acid, D-Glucuronic acid, (9Z,11E)-Octadecadienoic acid, and 9(10)-EpOME were identified as pivotal primary metabolites for rind puffing. Determination of lignin, protopectin, cellulose and lipoxygenase content further validated the relationship between cell wall, lipid metabolism and rind puffing. This study furnishes novel insights into the mechanisms underlying puffing disorder.

Progressive alterations in mineral contents in citrus genotypes toward Alternaria citri causing brown spot of citrus.

Brown spot of citrus caused by Alternaria citri is one of the emerging threats to the successful production of citrus crops. The present study, conducted with a substantial sample size of 50 leaf samples for statistical reliability, aimed to determine the change in mineral content in citrus leaves after brown spot disease attack. Leaf samples from a diverse range of susceptible citrus varieties (Valentia late, Washington navel, and Kinnow) and resistant varieties (Citron, Eruka lemon, and Mayer lemon) were analyzed. Significant variations (p ≤ 0.05) in mineral contents were observed across reaction groups (inoculated and un-inoculated), types (resistant and susceptible), and varieties of citrus in response to infection of Alternaria citri. The analysis of variance showed significant changes in mineral levels of citrus leaves, including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), sodium (Na), iron (Fe), and copper (Cu). The results indicate that the concentration of N and P differed by 6.63% and 1.44%, respectively, in resistant plants, while susceptible plants showed a difference of 6.07% and 1.19%. Moreover, resistant plants showed a higher concentrations of K, Ca, Mg, Zn, Na, Fe, and Cu at 8.40, 2.1, 1.83, 2.21, 1.58, 2.89, and 0.36 ppm respectively, compared to susceptible plants which showed concentrations of 5.99, 1.93, 1.47, 1.09, 1.24, 1.81, and 0.31 ppm respectively. Amounts of mineral contents were reduced in both resistant as well as susceptible plants of citrus after inoculation. Amount of N (8.56), P (1.87) % while K (10.74), Ca (2.71), Mg (2.62), Zn (2.20), Na (2.08), Fe (3.57) and Cu (0.20) ppm were recorded in un-inoculated group of citrus plants that reduced to 3.15 and 0.76% and 3.66, 1.40, 0.63,0.42, 0.74, 1.13 and 0.13 ppm in inoculated group respectively. It was accomplished that susceptible varieties contained lower ionic contents than resistant varieties. The higher concentrations of ionic contents in resistant citrus varieties build up the biochemical and physiological processes of the citrus plant, which help to restrict spread of pathogens. Further research could explore the interplay between mineral nutrition and disease resistance in citrus, potentially leading to the development of new disease-resistant varieties.

In vitro Propagation of <i>Citrus aurantifolia</i> and its Conservation in Pakistan

Citrus varieties are propagated by both asexual and sexual methods. Generally, rootstocks are propagated sexually through seeds, while most of the commercial varieties are propagated by various asexual methods such as grafting and budding. The technology called plant tissue culture is used for commercial production of plants that are microbe and virus free and to save germplasm of infrequent or threatened species of plants. Fast reproduction techniques have the potential to produce plants free of viruses. Likewise, traditional propagation methods are old, time consuming and are difficult. Tissue culture techniques are assumed for reliable commercial production of economically important plants. In present study shoot tips of Citrus aurantifolia were collected from the field of BCI, NARC. Different disinfectant (Ethanol and NaOCl) with the concentration ranging from 10 to 20 percent were used for culture establishment. Maximum survival percentage was observed in 10% NaOCl. After 5 weeks, established cultures were shifted to hormonal growth media (BAP, GA3 and NAA) at the concentration ranging from 0.1 to 0.8 mg/L. Our finding results that maximum phenotypic characters (plant height, number of leaves and number of shoots were observed on BAP at the concentration of 0.1 to 0.3 mg/L, while maximum number of roots were observed on NAA at the concentration of 0.5mg/L. In present study, for in vitro conservation different conservants like sorbitol and mannitol (10, 20 and 30 g/L) were used. Incubation of cultures was maintained at 21°C under the light intensity of 1000 lux. Old cultures of Citrus aurantifolia were shifted in conservant media. Overall, remarkable difference was observed. In present study mannitol at the concentration of (10, 20 and 30 g/L) showed slow growth after 35 days. In future the plants in conservation media will be used for further propagation and for growing them in fields.

Real-time citrus variety detection in orchards based on complex scenarios of improved YOLOv7.

Variety detection provides technical support for selecting XinHui citrus for use in the production of XinHui dried tangerine peel. Simultaneously, the mutual occlusion between tree leaves and fruits is one of the challenges in object detection. In order to improve screening efficiency, this paper introduces a YOLO(You Only Look Once)v7-BiGS(BiFormer&GSConv) citrus variety detection method capable of identifying different citrus varieties efficiently. In the YOLOv7-BiGS network model, initially, the BiFormer attention mechanism in the backbone of the YOLOv7-based network strengthens the model's ability to extract citrus' features. In addition, the introduction of the lightweight GSConv convolution in place of the original convolution within the ELAN of the head component effectively streamlines model complexity while maintaining performance integrity. To environment challenge validate the effectiveness of the method, the proposed YOLOv7-BiGS was compared with YOLOv5, YOLOv7, and YOLOv8. In the comparison of YOLOv7-BiGS with YOLOv5, YOLOv7, and YOLOv8, the experimental results show that the precision, mAP and recell of YOLOv7-BiGS are 91%, 93.7% and 87.3% respectively. Notably, compared to baseline methods, the proposed approach exhibited significant enhancements in precision, mAP, and recall by 5.8%, 4.8%, and 5.2%, respectively. To evaluate the efficacy of the YOLOv7-BiGS in addressing challenges posed by complex environmental conditions, we collected occluded images of Xinhui citrus fruits from the Xinhui orchard base for model detection. This research aims to fulfill performance criteria for citrus variety identification, offering vital technical backing for variety detection endeavors.

Efecto de la UV-C en la calidad postcosecha de cítricos de la región nororiente del Valle del Cauca, Colombia

Ultraviolet short wave (UV-C) irradiation is an emerging technology employed in postharvest fruits treatment. This method facilitates a reduction in microbial load, triggers an elicitor effect, and prolongs the shelf life of fruits. In this study, UV-C was applied to rangpur red lime, Tahitian lime, and sweet orange cv. 'Sweety,' which are the primary citrus varieties cultivated in the northeastern region of Valle del Cauca, Colombia. The citrus fruits were exposed to UV-C irradiation for 5 min using a lamp positioned 11 cm above the work area. Subsequently, the fruits were stored in plastic baskets for 21 days at 26 °C with a relative humidity of 70%. Positive and negative control treatments were also implemented. The positive treatment involved samples treated with a 150 mg/L sodium hypochlorite solution for 5 min, while the negative treatment comprised samples without any postharvest treatment. The results revealed that UV-C application effectively delayed maturation, prevented granulation, and maintained the physicochemical parameters, morphology, and surface color of citrus fruits. In conclusion, UV-C shows promise as a technology for treating citrus fruits during the postharvest stage, offering a means to mitigate losses, and assuring food availability.

The Citrus Variety Improvement Program in Turkey

The Citrus Variety Improvement Program in Turkey

Variability analysis of the Phenotypic Characteristics of some Grapefruit and Pomelo under Moroccan Conditions

Citrus is an economically important fruit crop with a long history of cultivation worldwide, and many citrus varieties are grown extensively in Morocco, both for domestic consumption and export. Nevertheless, the genetic diversity of this genus in Morocco has not been reported upon. Our objective was to explore phenotypic variations in grapefruit and pomelo genotypes for targeted breeding, enhancing key traits, and identifying opportunities for genetic improvement. We emphasize practical implications and outline future research directions for developing improved citrus varieties. This present study physiochemically analyzes eight grapefruit (Citrus paradisi) and two pomelo (Citrus maxima) cultivars to assess the genetic variability of these fruits’ physicochemical characteristics. The results revealed significant variance among the genotypes for all traits. For example, the phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV) for all the traits. Moreover, a high degree of heritability was recorded for seed number, β-carotene, vitamin C, juice yield (%), total soluble solids, titratable acidity, maturity index, fruit diameter, and fruit weight, whereas limited heritability was observed for fruit length, peel thickness, and segment number per fruit. The high genetic advance scores corresponded to the high degree of heritability estimates for seed number per fruit, β-carotene, juice yield, and vitamin C, suggesting the existence of additive genetic effects. Our principal component analysis (PCA) identified four components with cumulative variance of 93.20%, while hierarchical cluster analysis grouped the collection into five clusters. In conclusion, phenotypic distinctions among grapefruit and pomelo genotypes reveal opportunities for genetic enhancement through selection or hybridization. Varied traits, including seed count, vitamin C, beta-carotene, and juice yield, across genotypes suggest potential avenues for targeted breeding and practical applications in diverse citrus varieties.

The aroma profiles of dried gonggans: Characterization of volatile compounds in oven-dried and freeze-dried gonggan

Dehydration is an effective method for the long-term storage and aroma retention of gonggan (Citrus sinensis Osb. ‘Deqing Gonggan’), which is a Chinese variety of citrus, with unique and characteristic floral, fruity, and citrus flavors. However, the aroma profiles of gonggans prepared using oven- and freeze-drying, the most widely-used drying methods, remain unclear. In this study, a total of 911 volatile organic compounds (VOCs) were detected in dried gonggan. These were primarily composed of alcohols (7.69%), aldehydes (7.03%), esters (15.38%), ketones (7.58%), and terpenoids (23.19%). A total of 67 odorants contributed significantly to the overall aroma of dried gonggans, with the major odor qualities being detected as green, citrus, fruity, floral, and sweet. These were mainly attributed to the presence of aldehydes, esters, and terpenoids. Freeze-drying was more effective in maintaining the unique citrus and mandarin-like aromas attributed to compounds such as limonene, citrial, β-myrcene, β-pinene, and γ-terpinene. Moreover, (E,E)-2,4-decadienal had the highest relative odor activity value (rOAV) in freeze-dried gonggans, followed by (E)-2-nonenal, furaneol, (E, E)-2, 4-nonadienal, and E-2-undecenal. Oven-drying promoted the accumulation of terpenes such as octatriene, trans-β-ocimene, cyclohexanone, copaene, and ɑ-irone, imparting a soft aroma of flowers, fruits, and sweet. Increasing the temperature led to an increase in existing VOCs or the generation of new VOCs through phenylpropanoid, terpenoid, and fatty acid metabolism. The findings of this study offer insights into an optimized procedure for producing high-quality dried gonggans. These insights can be valuable for the fruit-drying industry, particularly for enhancing the quality of dried fruits.

Essential oils of indigenous citrus varieties of Northeast India as potential antibiofilm agents against foodborne pathogens: An in vitro and in silico study

Essential oils of indigenous citrus varieties of Northeast India as potential antibiofilm agents against foodborne pathogens: An in vitro and in silico study

Comparative Transcriptome and sRNAome Analysis Suggest Coordinated Citrus Immune Responses against Huanglongbing Disease.

Citrus Huanglongbing (HLB), caused by the phloem-inhibiting bacterium Candidatus Liberibacter asiaticus (CLas), is the most devastating citrus disease, intimidating citrus production worldwide. Although commercially cultivated citrus cultivars are vulnerable to CLas infection, HLB-tolerant attributes have, however, been observed in certain citrus varieties, suggesting a possible pathway for identifying innate defense regulators that mitigate HLB. By adopting transcriptome and small RNAome analysis, the current study compares the responses of HLB-tolerant lemon (Citrus limon L.) with HLB-susceptible Shatangju mandarin (Citrus reticulata Blanco cv. Shatangju) against CLas infection. Transcriptome analysis revealed significant differences in gene expression between lemon and Shatangju. A total of 1751 and 3076 significantly differentially expressed genes were identified in Shatangju and lemon, respectively. Specifically, CLas infected lemon tissues demonstrated higher expressions of genes involved in antioxidant enzyme activity, protein phosphorylation, carbohydrate, cell wall, and lipid metabolism than Shatangju. Wet-lab experiments further validated these findings, demonstrating increased antioxidant enzyme activity in lemon: APX (35%), SOD (30%), and CAT (64%) than Shatangju. Conversely, Shatangju plants exhibited higher levels of oxidative stress markers like H2O2 (44.5%) and MDA content (65.2%), alongside pronounced ion leakage (11.85%), than lemon. Moreover, microscopic investigations revealed that CLas infected Shatangju phloem exhibits significantly more starch and callose accumulation than lemon. Furthermore, comparative sRNA profiles revealed the potential defensive regulators for HLB tolerance. In Shatangju, increased expression of csi-miR166 suppresses the expression of disease-resistant proteins, leading to inadequate defense against CLas. Conversely, reduced expression of csi-miR166 in lemon plants enables them to combat HLB by activating disease-resistance proteins. The above findings indicate that when infected with CLas, lemon exhibits stronger antioxidative activity and higher expression of disease-resistant genes, contributing to its enhanced tolerance to HLB. In contrast, Shatangju shows lower antioxidative activity, reduced expression of disease-resistant genes, significant ion leakage, and extensive callose deposition, possibly related to damage to plant cell structure and blockage of phloem sieve tubes, thereby promoting the development of HLB symptoms.

Investigation the differences in key taste-contributing substances between Shitougan(Citrus reticulata Blanco Cv. Manau Gan) and other citrus varieties

Investigation the differences in key taste-contributing substances between Shitougan(Citrus reticulata Blanco Cv. Manau Gan) and other citrus varieties

Unveiling the Chemistry of Citrus Peel: Insights into Nutraceutical Potential and Therapeutic Applications.

The recent millennium has witnessed a notable shift in consumer focus towards natural products for addressing lifestyle-related disorders, driven by their safety and cost-effectiveness. Nutraceuticals and functional foods play an imperative role by meeting nutritional needs and offering medicinal benefits. With increased scientific knowledge and awareness, the significance of a healthy lifestyle, including diet, in reducing disease risk is widely acknowledged, facilitating access to a diverse and safer diet for longevity. Plant-based foods rich in phytochemicals are increasingly popular and effectively utilized in disease management. Agricultural waste from plant-based foods is being recognized as a valuable source of nutraceuticals for dietary interventions. Citrus peels, known for their diverse flavonoids, are emerging as a promising health-promoting ingredient. Globally, citrus production yields approximately 15 million tons of by-products annually, highlighting the substantial potential for utilizing citrus waste in phyto-therapeutic and nutraceutical applications. Citrus peels are a rich source of flavonoids, with concentrations ranging from 2.5 to 5.5 g/100 g dry weight, depending on the citrus variety. The most abundant flavonoids in citrus peel include hesperidin and naringin, as well as essential oils rich in monoterpenes like limonene. The peel extracts exhibit high antioxidant capacity, with DPPH radical scavenging activities ranging from 70 to 90%, comparable to synthetic antioxidants like BHA and BHT. Additionally, the flavonoids present in citrus peel have been found to have antioxidant properties, which can help reduce oxidative stress by 30% and cardiovascular disease by 25%. Potent anti-inflammatory effects have also been demonstrated, reducing inflammatory markers such as IL-6 and TNF-α by up to 40% in cell culture studies. These findings highlight the potential of citrus peel as a valuable source of nutraceuticals in diet-based therapies.

Investigating population dynamics and evaluating damage incurred by Thripidae (Thysanoptera) species in citrus orchards of Northeastern Morocco: an exemplary analysis in Berkane

Thrips are significant pest of crops, vegetables, and fruiting trees, and various species of thrips can infest citrus at fruit formation as well as new leaf sprouts. Thrips presence and damage can significantly reduce the export value of fruits, making them a major concern for citrus growers. Field studies were conducted to investigate the biodiversity and abundance of citrus thrips on an early fruiter citrus cultivar in experimental and commercial orchards of Morocco. In this study, we investigated the abundance, economic importance, dynamics, and seasonal fluctuations of citrus thrips in relation to citrus phenology. We identified four species of thrips that infest citrus orchards, including Frankliniella occidentalis, Pezothrips kellyanus, Scirtothrips sp, and Aeolothrips sp. Our results showed that the quantitative peak of thrips occurred during the blooming stage, and that the number of thrips caught on sticky traps during bloom could be a suitable predictive method for estimating final fruit damage. The population dynamics of thrips species were found to depend on several biotic and abiotic factors, including temperature, rainfall, and chemical interventions. We also observed that some citrus varieties were more susceptible to thrips attacks than others, with Washington navel and Maroc late being the most infested orchards with infestation rates of 32% and 24%, respectively. Our findings provide important insights into the abundance, economic importance, and seasonal fluctuations of citrus thrips, which can inform the development of effective control strategies to mitigate their damage in citrus orchards.

Optimized nutrients management improved citrus yield and fruit quality in China: A meta-analysis

Clarifying current situation of farmers' fertilization and yield in citrus producing areas and the effects of different fertilization measures can provide a scientific basis for improving the yield and quality of citrus in China. We retrieved 92 literatures on citrus fertilization from the CNKI and Web of Science to examine the impacts of nitrogen (N), phosphorus (P or P2O5), and potassium (K or K2O) fertilizer dosage and partial productivity under farmers' conventional fertilization and experts' optimized fertilization, as well as the effects of optimized fertilization measures on citrus yield and quality by using meta-analysis approach. The average conventional application rates of N, P2O5, and K2O were 507.3, 262.2, and 369.3 kg·hm-2 in citrus production in China. Compared with conventional fertilization, optimized fertilization resulted in a reduction of N and P2O5 by 14.7% and 8.3%, an increase in K2O application by 6.6%, which promoted partial productivity of N, P2O5, and K2O fertilizers by 7.8%, 18.4%, and 14.7%, correspondingly. The optimized fertilization resulted in 11.9% and 2.8% increase in fruit yield and single fruit weight, while improved vitamin C content (Vc, 3.1%), total soluble solids (TSS, 5.9%) and total sugar content (TSC, 8.6%). Additionally, it also led to a reduction in titratable acid (TA, -3.4%) and total acid content (TAC, -3.6%), and consequently elevated the TSS/TA (14.0%) and TSC/TAC (9.5%). Among different optimized fertilization methods, the effect of optimized NPK + medium and/or micro element fertilizer on citrus yield and fruit quality was the best, especially NPK decrement ≤25% between optimized NPK measures. The effect of conventional NPK + organic fertilizer was higher than conventional NPK + medium and/or micro element fertilizer. However, different citrus varieties, including mandarins, pomelos, and oranges, showed different responses to optimized fertilization. Optimized fertilization management could synergistically improve citrus yield, fertilizer use efficiency, and fruit quality. Therefore, the strategy of integrated nutrient management1 with reducing NPK fertilizer, balancing medium and/or micro nutrient fertilizer and improving soil fertility by organic fertilizer should be adopted according to local conditions in citrus producing areas of China.

Assessment of the health status of citrus propagation material against hop stunt viroid through biological and molecular diagnosis

Hop stunt viroid (HSVd) is the causal agent of citrus cachexia, which can lead to significant crop losses. As part of a preventive management strategy, it is essential to use healthy plants from a certification program. This study aimed to, healthiness of 17 citrus cultivars was evaluated against HSVd using both biological and molecular diagnostics. For biological diagnosis, Etrog citron (Citrus medica L.) clone Arizona 861 S1 was used as an indicator plant, incorporating negative and positive controls for HSVd infection. For molecular diagnosis, reverse transcription polymerase chain reaction (RT-PCR) technique was employed with specific primers for viroid detection. Results indicated that six months after inoculation, the positive control exhibited symptoms associated with viroid infection, such as necrosis in the petiole and stem, leaf epinasty, and necrosis in the midvein. In contrast, both the negative control and evaluated citrus cultivars showed no symptoms. These findings were supported by molecular analysis, which allowed the amplification of a viroid genome region only in the positive control. Both biological and molecular diagnosis confirmed the absence of HSVd in the citrus varieties assessed. This study will allow the evaluation of the citrus plant collections used in the foundation category as a source of buds for plant multiplication of registered and certified seeds for citrus propagation nurseries in Colombia.

Antibacterial activity of Cymbopogon species essential oils against Xanthomonas citri and their use in post-harvest treatment for citrus canker management.

Citrus canker is a disease caused by the gram-negative bacterium Xanthomonas citri subp. citri (X. citri), which affects all commercially important varieties of citrus and can lead to significant losses. Fruit sanitization with products such as chlorine-based ones can reduce the spread of the disease. While effective, their use raises concerns about safety of the workers. This work proposes essential oils (EOs) as viable alternatives for fruit sanitization. EOs from Cymbopogon species were evaluated as to their antibacterial activity, their effect on the bacterial membrane, and their ability to sanitize citrus fruit. The in vitro assays revealed that the EOs from C. schoenanthus and C. citratus had a lower bactericidal concentration at 312mg L-1, followed by 625mg L-1 for C. martini and C. winterianus. Microscopy assay revealed that the bacterial cell membranes were disrupted after 15min of contact with all EOs tested. Regarding the sanitizing potential, the EOs with higher proportions of geraniol were more effective in sanitizing acid limes. Fruit treated with C. shoenanthus and C. martini showed a reduction of ∼68% in the recovery of viable bacterial cells. Therefore, these EOs can be used as viable natural alternatives in citrus fruit disinfection.