Candidatus Liberibacter Asiaticus Manipulates the Expression of Vitellogenin, Cytoskeleton, and Endocytotic Pathway-Related Genes to Become Circulative in Its Vector, Diaphorina citri (Hemiptera: Psyllidae)

Citrus greening disease or huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) limits the citrus production worldwide. CLas is transmitted by the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae) in a persistent-propagative manner. Application of insecticides to manage the psyllid vectors and disease is the most common practice. Understanding the molecular interaction between CLas and ACP and interrupting the interrelationship can provide an alternative to insecticides for managing citrus greening disease. Transcriptome analysis of ACP in response to CLas showed differential expression of 3911 genes (2196 up-regulated, and 1715 down-regulated) including the key genes of ACP involved in cytoskeleton synthesis and nutrition-related proteins. Majority of the differentially expressed genes were categorized under molecular function followed by cellular components and biological processes. KEGG pathway analysis showed differential regulation of carbohydrate, nucleotide and energy metabolic pathways, the endocytotic pathway and the defense-related pathways. Differential regulation of genes associated with the key pathways might favors CLas to become systemic and propagate in its insect vector. The study provides an understanding of genes involved in circulation of CLas in ACP. The candidate genes involved in key physiological processes and CLas transmission by ACP would be potential targets for sustainable management of ACP and CLas.

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Asian citrus psyllid adults inoculate huanglongbing bacterium more efficiently than nymphs when this bacterium is acquired by early instar nymphs

Scientific Reports ◽

10.1038/s41598-020-75249-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

El-Desouky Ammar ◽

Justin George ◽

Kasie Sturgeon ◽

Lukasz L. Stelinski ◽

Robert G. Shatters

Keyword(s):

Latent Period ◽

Salivary Glands ◽

Emerging Adults ◽

Citrus Greening ◽

Asian Citrus Psyllid ◽

Diaphorina Citri ◽

Citrus Greening Disease ◽

Early Instar ◽

Liberibacter Asiaticus ◽

Greening Disease

Abstract The Asian citrus psyllid (Diaphorina citri) transmits the bacterium ‘Candidatus Liberibacter asiaticus’ (CLas), which causes huanglongbing (citrus greening) disease, in a circulative-propagative manner. We compared CLas inoculation efficiency of D. citri nymphs and adults into healthy (uninfected) citron leaves when both vector stages were reared from eggs on infected plants. The proportion of CLas-positive leaves was 2.5% for nymphs and 36.3% for adults. CLas acquisition by early instar nymphs followed by dissections of adults and 4th instar nymphs revealed that CLas bacterium had moved into the head-thorax section (containing the salivary glands) in 26.7–30.0% of nymphs and 37–45% of adults. Mean Ct values in these sections were 31.6–32.9 and 26.8–27.0 for nymphs and adults, respectively. Therefore, CLas incidence and titer were higher in the head-thorax of adults than in nymphs. Our results suggest that following acquisition of CLas by early instar D. citri nymphs, emerging adults inoculate the bacteria into citrus more efficiently than nymphs because adults are afforded a longer latent period necessary for multiplication and/or translocation of CLas into the salivary glands of the vector. We propose that CLas uses D. citri nymphs mainly for pathogen acquisition and multiplication, and their adults mainly for pathogen inoculation and spread.

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Citrus tristeza virus-based RNAi in citrus plants induces gene silencing in Diaphorina citri, a phloem-sap sucking insect vector of citrus greening disease (Huanglongbing)

Journal of Biotechnology ◽

10.1016/j.jbiotec.2014.02.010 ◽

2014 ◽

Vol 176 ◽

pp. 42-49 ◽

Cited By ~ 80

Author(s):

Subhas Hajeri ◽

Nabil Killiny ◽

Choaa El-Mohtar ◽

William O. Dawson ◽

Siddarame Gowda

Keyword(s):

Gene Silencing ◽

Citrus Tristeza Virus ◽

Citrus Greening ◽

Insect Vector ◽

Diaphorina Citri ◽

Phloem Sap ◽

Citrus Greening Disease ◽

Greening Disease ◽

Tristeza Virus ◽

Citrus Tristeza

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Proteomic Polyphenism in Color Morphotypes of Diaphorina citri, Insect Vector of Citrus Greening Disease

Journal of Proteome Research ◽

10.1021/acs.jproteome.1c00089 ◽

2021 ◽

Author(s):

Saeed Hosseinzadeh ◽

Steven A. Higgins ◽

John Ramsey ◽

Kevin Howe ◽

Michael Griggs ◽

...

Keyword(s):

Citrus Greening ◽

Insect Vector ◽

Diaphorina Citri ◽

Citrus Greening Disease ◽

Greening Disease

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Understanding Citrus Greening Disease and Its Possible Management Strategies in Nepal

International Journal of Applied Sciences and Biotechnology ◽

10.3126/ijasbt.v9i4.40805 ◽

2021 ◽

Vol 9 (4) ◽

pp. 227-234

Author(s):

Sameer Pokhrel ◽

Swikriti Pandey ◽

Ashish Ghimire ◽

Savyata Kandel

Keyword(s):

Management Strategies ◽

Citrus Greening ◽

Insect Vector ◽

Candidatus Liberibacter Asiaticus ◽

Citrus Greening Disease ◽

The World ◽

Citrus Production ◽

Candidatus Liberibacter ◽

Liberibacter Asiaticus ◽

Citrus Orchards

Huanglongbing (HLB), also known as citrus greening, is a devastating disease of citrus that has decimated several citrus orchards throughout the world. The disease is associated with three species of unculturable and phloem-limited bacteriae, Candidatus Liberibacter asiaticus, Candidatus Liberibacter africanus and Candidatus Liberibacter americanus. The most common species of bacteria found in Nepal is Candidatus Liberibacter asiaticus which is transmitted by an insect vector, Asian citrus psyllid (Diaphorina citri). This disease has been detected in several economically important citrus production areas of Nepal, which resulted in heavy yield loss. No cure for the disease has been discovered yet and it is essential to practice proper management strategies to maintain citrus health and sustain citrus production under HLB pressure. Several disease management approaches such as pathogen-free nursery establishment, use of disease tolerant rootstock cultivars, proper irrigation and nutrient supply, removal of HLB affected trees, and control of psyllid with frequent insecticide application are widely practiced throughout the world. This review article highlights the characteristics of the citrus greening disease and its insect vector and gives insights into their management techniques. Several technologically advanced options available to minimize the HLB infection might not be feasible currently in Nepal due to economic and topographic constraints. This article also aims to bring into focus the cost-effective methods that growers in Nepal can practice to mitigate the impact of HLB disease in their citrus orchards. Int. J. Appl. Sci. Biotechnol. Vol 9(4): 227-238.

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