Citrus leaf volatiles response to ‘Candidatus Liberibacter asiaticus’ and to its insect vector Asian citrus psyllid

Abstract Plant pathogenic bacteria interact with their insect host(s)/vector(s) at the cellular and molecular levels. This interaction may alter the physiology of their insect vector, which may also promote the growth and transmission of the bacterium. Here we studied the effect of “Candidatus Liberibacter asiaticus” (“Ca. L. asiaticus”) on physiochemical conditions within its insect vector, the Asian citrus psyllid (ACP), and whether these changes were beneficial for the pathogen. The local microenvironments inside ACPs were quantified using microelectrodes. The average hemolymph pH was significantly higher in infected ACPs (8.13 ± 0.21) than in “Ca. L. asiaticus”-free ACPs (7.29 ± 0.15). The average hemolymph oxygen tension was higher in “Ca. L. asiaticus”-free ACPs than in infected ACPs (67.13% ± 2.11% vs. 35.61% ± 1.26%). Oxygen tension reduction and pH increase were accompanied by “Ca. L. asiaticus” infection. Thus, oxygen tension of the hemolymph is an indicator of infection status, with pH affected by the severity of the infection.

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The Asian Citrus Psyllid Host Murraya koenigii Is Immune to Citrus Huanglongbing Pathogen ‘Candidatus Liberibacter asiaticus’

Phytopathology ◽

10.1094/phyto-01-18-0012-r ◽

2018 ◽

Vol 108 (9) ◽

pp. 1089-1094 ◽

Cited By ~ 6

Author(s):

Vitor H. Beloti ◽

Gustavo R. Alves ◽

Helvécio D. Coletta-Filho ◽

Pedro T. Yamamoto

Keyword(s):

Infected Plant ◽

Asian Citrus Psyllid ◽

Test Plant ◽

Insect Vector ◽

Candidatus Liberibacter Asiaticus ◽

Murraya Koenigii ◽

Trap Crop ◽

Candidatus Liberibacter ◽

Citrus Huanglongbing ◽

Liberibacter Asiaticus

The Asian citrus psyllid (ACP) Diaphorina citri, vector of ‘Candidatus Liberibacter asiaticus’ (CLas), the putative causal agent of citrus Huanglongbing (HLB), is controlled by application of insecticides, which, although effective, has resulted in serious biological imbalances. New management tools are needed, and the technique known as “trap crop” has been attracting attention. A potential plant for use as a trap crop in the management of the ACP is Murraya koenigii (curry leaf). However, for this plant to be used in the field, it needs to be attractive for the vector and must not harbor CLas. To verify the potential of curry leaf as trap crop for the management of HLB, we investigated the ability of D. citri to transmit CLas to M. koenigii, and to other test plants, including M. paniculata (orange jasmine) and cultivar Valencia sweet-orange seedlings. For the tests, the insects were reared on a symptomatic CLas-infected plant and allowed to feed on the three test plant species. The overall maximum transmission rate for the citrus seedlings was 83.3%, and for orange jasmine was 33.3%. Successful transmission of CLas by ACP to the curry-leaf seedlings was not observed, and it was treated as immune to CLas. Supported by the previous results that M. koenigii is attractive for ACP, these results indicate that curry leaf is an excellent candidate for use as a trap crop, to improve the management of the insect vector and consequently of HLB.

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Transcriptomic and Metabolomic Analyses of Diaphorina citri Kuwayama Infected and Non-infected With Candidatus Liberibacter Asiaticus

Frontiers in Physiology ◽

10.3389/fphys.2020.630037 ◽

2021 ◽

Vol 11 ◽

Author(s):

Kai Liu ◽

Jiawei He ◽

Ziying Guan ◽

Mingzhao Zhong ◽

Rui Pang ◽

...

Keyword(s):

Mass Spectrometry ◽

Host Plants ◽

Integrated Analysis ◽

Asian Citrus Psyllid ◽

Insect Vector ◽

Diaphorina Citri ◽

Liquid Chromatography Mass Spectrometry ◽

Candidatus Liberibacter Asiaticus ◽

Candidatus Liberibacter ◽

Liberibacter Asiaticus

The Asian citrus psyllid Diaphorina citri is the transmission vector of Huanglongbing (HLB), a devastating disease of citrus plants. The bacterium “Candidatus Liberibacter asiaticus” (CLas) associated with HLB is transmitted between host plants by D. citri in a circulative manner. Understanding the interaction between CLas and its insect vector is key for protecting citrus cultivation from HLB damage. Here, we used RNA sequencing and liquid chromatography-mass spectrometry (LC-MS) to analyze the transcriptome and metabolome of D. citri interacting with CLas. We identified 662 upregulated and 532 downregulated genes in CLas-infected insects. These genes were enriched in pathways involving carbohydrate metabolism, the insects’ immune system, and metabolism of cofactors and vitamins. We also detected 105 differential metabolites between CLas-infected and non-infected insects, including multiple nucleosides and lipid-related molecules. The integrated analysis revealed nine pathways—including those of the glycine, serine, threonine, and purine metabolism—affected by the differentially expressed genes from both groups. The network for these pathways was subsequently constructed. Our results thus provide insights regarding the cross-talk between the transcriptomic and metabolomic changes in D. citri in response to CLas infection, as well as information on the pathways and genes/metabolites related to the CLas–D. citri interaction.

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Susceptibility of Sixteen Citrus Genotypes to ‘Candidatus Liberibacter asiaticus’

Plant Disease ◽

10.1094/pdis-08-15-0940-re ◽

2016 ◽

Vol 100 (6) ◽

pp. 1080-1086 ◽

Cited By ~ 10

Author(s):

Greg McCollum ◽

Mark Hilf ◽

Mike Irey ◽

Weiqi Luo ◽

Tim Gottwald

Keyword(s):

The United States ◽

Insect Vector ◽

Candidatus Liberibacter Asiaticus ◽

Citrus Germplasm ◽

Citrus Production ◽

Candidatus Liberibacter ◽

Liberibacter Asiaticus ◽

Florida Citrus ◽

Citrus Macrophylla ◽

Free Ranging

Huanglongbing (HLB) disease is the most serious threat to citrus production worldwide and, in the last decade, has devastated the Florida citrus industry. In the United States, HLB is associated with the phloem-limited α-proteobacterium ‘Candidatus Liberibacter asiaticus’ and its insect vector, the Asian citrus psyllid (ACP; Diaphorina citri). Significant effort is being put forth to develop novel citrus germplasm that has a lower propensity to succumb to HLB than do currently available varieties. Effective methods of screening citrus germplasm for susceptibility to HLB are essential. In this study, we exposed small, grafted trees of 16 citrus types to free-ranging ACP vectors and ‘Ca. L. asiaticus’ inoculum in the greenhouse. During 45 weeks of exposure to ACP, the cumulative incidence of ‘Ca. L. asiaticus’ infection was 70%. Trees of Citrus macrophylla and C. medica were most susceptible to ‘Ca. L. asiaticus’, with 100% infection by the end of the test period in three trials, while the complex genetic hybrids ‘US 1-4-59’ and ‘Fallglo’ consistently were least susceptible, with approximately 30% infection. Results obtained in this greenhouse experiment showed good agreement with trends observed in the orchard, supporting the validity of our approach for screening citrus germplasm for susceptibility to HLB.

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Probing the application of OmpA-derived peptides to disrupt the acquisition of ‘Candidatus Liberibacter asiaticus’ by Diaphorina citri

Phytopathology ◽

10.1094/phyto-06-21-0252-fi ◽

2021 ◽

Author(s):

Marcus Vinicius Merfa e Silva ◽

Eduarda Regina Fischer ◽

Mariana de Souza e Silva ◽

Carolina Sardinha Francisco ◽

Helvécio Coletta-Filho ◽

...

Keyword(s):

Control Strategies ◽

Insect Vector ◽

Diaphorina Citri ◽

Candidatus Liberibacter Asiaticus ◽

In Planta ◽

Host Interaction ◽

Vector Population ◽

Candidatus Liberibacter ◽

Liberibacter Asiaticus ◽

Bacterial Outer Membrane

Huanglongbing (HLB) is currently the most devastating disease of citrus worldwide. Both bacteria ‘Candidatus Liberibacter asiaticus’ (CLas) and ‘Ca. Liberibacter americanus’ (CLam) are associated with HLB in Brazil, but with a strong prevalence of CLas over CLam. Conventionally, HLB management focuses on controlling the insect vector population (Diaphorina citri; also known as Asian citrus psyllid – ACP) by spraying insecticides, an approach demonstrated to be mostly ineffective. Thus, development of novel more efficient HLB control strategies is required. The multifunctional bacterial outer membrane protein OmpA is involved in several molecular processes between bacteria and their hosts and has been suggested as a target for bacterial control. Curiously, OmpA is absent in CLam in comparison to CLas, suggesting a possible role on host-interaction. Therefore, in the current study, we have treated ACPs with different OmpA-derived peptides aiming to evaluate the acquisition of CLas by the insect vector. Treatment of psyllids with 5 µM of Pep1, Pep3, Pep5 and Pep6 in artificial diet significantly reduced the acquisition of CLas, while increasing the concentration of Pep5 and Pep6 to 50 µM abolished this process. In addition, in planta treatment with 50 µM of Pep6 also significantly decreased the acquisition of CLas and sweet orange plants stably absorbed and maintained this peptide for as long as three months post the final application. Together, our results demonstrate the promising use of OmpA-derived peptides as a novel biotechnological tool to control CLas.

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A Review of Huanglongbing (Citrus Greening) Management in Citrus Using Nutritional Approaches in China

Plant Health Progress ◽

10.1094/php-2010-1003-01-rv ◽

2011 ◽

Vol 12 (1) ◽

pp. 24 ◽

Cited By ~ 7

Author(s):

Yulu Xia ◽

Gecheng Ouyang ◽

Ronald A. Sequeira ◽

Yu Takeuchi ◽

Ignacio Baez ◽

...

Keyword(s):

Nutrient Management ◽

Field Survey ◽

Cultural Practices ◽

Sweet Orange ◽

Asian Citrus Psyllid ◽

Diaphorina Citri ◽

Candidatus Liberibacter Asiaticus ◽

Candidatus Liberibacter ◽

Citrus Maxima ◽

Liberibacter Asiaticus

The Asian form of huanglongbing (HLB) is caused by ‘Candidatus Liberibacter asiaticus (Las),’ a phloem-limited bacterium transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama. Nutrient management, together with other cultural practices such as pruning and irrigation, for mitigation of the disease has been practiced in China for many years. Our literature review, field survey, and interviews with Chinese scientists and growers indicate that these cultural practices were generally ineffective for the disease management. However, a nutritional approach in conjunction with other cultural practices such as irrigation can maintain grove productivity for a certain time depending on the type of citrus species/cultivars, the age of the trees, the propagation method of the plants, the Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) population, and other factors. Symptomatic mature pommelo (Citrus maxima Merr) and sweet orange (C. sinensis L. Osbeck) plants can commonly survive and maintain a certain level of productivity for an additional 4 to 5 years, even longer assuming vigorous ACP control. Accepted for publication 27 June 2011. Published 3 October 2011.

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Tracing Penicillin Movement in Citrus Plants Using Fluorescence-Labeled Penicillin

Antibiotics ◽

10.3390/antibiotics8040262 ◽

2019 ◽

Vol 8 (4) ◽

pp. 262

Author(s):

Nabil Killiny ◽

Pedro Gonzalez-Blanco ◽

Yulica Santos-Ortega ◽

Fuad Al-Rimawi ◽

Amit Levy ◽

...

Keyword(s):

Vascular Tissue ◽

Vascular System ◽

Citrus Greening ◽

Application Site ◽

Asian Citrus Psyllid ◽

Diaphorina Citri ◽

Candidatus Liberibacter Asiaticus ◽

Citrus Industry ◽

Candidatus Liberibacter ◽

Liberibacter Asiaticus

Huánglóngbìng (HLB), citrus greening, is one of the most destructive diseases of citrus plants worldwide. In North America, HLB is caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus and is transmitted by the Asian citrus psyllid, Diaphorina citri. No cure exists at present, and the use of antibiotics for the control of HLB has gained interest due to the significant losses to the citrus industry. Because of unsatisfactory results when using foliar applications of antibiotics, concerns were raised regarding the uptake and translocation of these materials within trees. We, therefore, investigated a method that allows us to study the movement of antibiotic materials in citrus plants. Herein, we utilized a fluorescence-labeled penicillin, BOCILLIN™ FL-Penicillin (FL-penicillin), to study the uptake and translocation of penicillin in citrus plants. FL-penicillin was applied by puncture to the stem of young citrus seedlings and was traced by using fluorescence microscopy. After application, we detected FL-penicillin in the leaves and in the stem xylem and phloem tissues above and below the application site in both intact and partially bark-girdled citrus seedlings, indicating that it is easily taken up and transported through the plant vascular system. In addition, we detected FL-penicillin in the gut of D. citri, which were allowed to feed on the treated plants, suggesting translocation of this molecule into the vascular tissue. We propose that the use of fluorescent-labeled molecules could be an effective tool for understanding the uptake and translocation of antibiotics and other macromolecules in plants and insects.

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