scholarly journals Detection of ‘Candidatus Liberibacter asiaticus’ in Diaphorina citri and Its Importance in the Management of Citrus Huanglongbing in Florida

2008 ◽  
Vol 98 (4) ◽  
pp. 387-396 ◽  
Author(s):  
K. L. Manjunath ◽  
S. E. Halbert ◽  
C. Ramadugu ◽  
S. Webb ◽  
R. F. Lee
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain ◽  
Polymerase Chain Reaction Methodology

Citrus huanglongbing (HLB or citrus greening), is a highly destructive disease that has been spreading in both Florida and Brazil. Its psyllid vector, Diaphorina citri Kuwayama, has spread to Texas and Mexico, thus threatening the future of citrus production elsewhere in mainland North America. Even though sensitive diagnostic methods have been developed for detection of the causal organisms, Candidatus Liberibacter spp., the pathogen cannot be detected consistently in plants until symptoms develop, presumably because of low titer and uneven distribution of the causal bacteria in nonsymptomatic tissues. In the present study, TaqMan based real-time quantitative polymerase chain reaction methodology was developed for detection of ‘Ca. L. asiaticus’ in D. citri. Over 1,200 samples of psyllid adults and nymphs, collected from various locations in Florida, from visually healthy and HLB symptomatic trees at different times of the year were analyzed to monitor the incidence and spread of HLB. The results showed that spread of ‘Ca. L. asiaticus’ in an area may be detected one to several years before the development of HLB symptoms in plants. The study suggests that discount garden centers and retail nurseries may have played a significant role in the widespread distribution of psyllids and plants carrying HLB pathogens in Florida.

scholarly journals Seasonal Variation of ‘Candidatus Liberibacter asiaticus’ Titers in New Shoots of Citrus in Distinct Environments

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 583-590 ◽  
Author(s):  
Silvio A. Lopes ◽  
Fernanda Q. B. F. Luiz ◽  
Hermes T. Oliveira ◽  
Juan C. Cifuentes-Arenas ◽  
Laudecir L. Raiol-Junior
Keyword(s):  
Sweet Orange ◽  
Quantitative Polymerase Chain Reaction ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Cumulative Rainfall ◽  
Data Loggers ◽  
Minas Gerais State ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain

The major citrus area of Brazil occupies near 450,000 ha between the Triângulo Mineiro (TM) region of Minas Gerais State and the south of São Paulo State (SPS). Significant climatic variation occurs between regions which could affect huanglongbing (HLB) progress, which is lower in TM. To investigate this possibility, young sweet orange shoots were sampled periodically over 2 years to determine ‘Candidatus Liberibacter asiaticus’ titers in naturally infected trees in orchards in Analândia, central SPS, and Frutal and Comendador Gomes, within TM. Data-loggers recorded local temperature and relative humidity hourly. In the laboratory, five ‘Ca. L. asiaticus’-free Diaphorina citri adults were placed on each sampled shoot for 48 h to feed and acquire the pathogen. Shoots and insects were individually analyzed by quantitative polymerase chain reaction to determine ‘Ca. L. asiaticus’ titers. The incidence of ‘Ca. L. asiaticus’-positive shoots, ‘Ca. L. asiaticus’ titers, and acquisition rates were lower for shoots from Comendador Gomes than those from Frutal or Analândia. Stronger association was observed between ‘Ca. L. asiaticus’ titers and the number of hours below 15°C (h < 15°C) or above 30°C (h > 30°C), and cumulative rainfall registered during the 15 days prior to sampling of shoots on each occasion. ‘Ca. L. asiaticus’ titers associated positively with h < 15°C and rainfall and negatively with h > 30°C. The slower spread and lower incidence of HLB in TM may be related to lower incidences of ‘Ca. L. asiaticus’-positive young shoots and lower titers of ‘Ca. L. asiaticus’ in the same shoots as a consequence of the warmer and drier conditions.

scholarly journals Resolution of the Identity of ‘Candidatus Liberibacter’ Species From Huanglongbing-Affected Citrus in East Africa

Plant Disease ◽  
2017 ◽  
Vol 101 (8) ◽  
pp. 1481-1488 ◽  
Author(s):  
Ronel Roberts ◽  
Glynnis Cook ◽  
Tim G. Grout ◽  
Fathiya Khamis ◽  
Ivan Rwomushana ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Housekeeping Genes ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Resolution Of The Identity

‘Candidatus Liberibacter asiaticus’, the bacterium associated with citrus Huanglongbing (HLB), was reported from Uganda and tentatively from Tanzania, posing a threat to citriculture in Africa. Two surveys of citrus expressing typical HLB symptoms were conducted in Uganda, Kenya, and Tanzania to verify reports of ‘Ca. L. asiaticus’ and to assess the overall threat of HLB to eastern and southern African citrus production. Samples were analyzed for the presence of ‘Candidatus Liberibacter’ species by real-time PCR and partial sequencing of three housekeeping genes, 16S rDNA, rplJ, and omp. ‘Ca. L. africanus’, the bacterium historically associated with HLB symptoms in Africa, was detected in several samples. However, samples positive in real-time PCR for ‘Ca. L. asiaticus’ were shown not to contain ‘Ca. L. asiaticus’ by sequencing. Sequences obtained from these samples were analogous to ‘Ca. L. africanus subsp. clausenae’, identified from an indigenous Rutaceae species in South Africa, and not to ‘Ca. L. asiaticus’. Results indicate a nontarget amplification of the real-time assay and suggest that previous reports of ‘Ca. L. asiaticus’ from Uganda and Tanzania may be mis-identifications of ‘Ca. L. africanus subsp. clausenae’. This subspecies was additionally detected in individual Diaphorina citri and Trioza erytreae specimens recovered from collection sites. This is the first report of ‘Ca. L. africanus subsp. clausenae’ infecting citrus and being associated with HLB symptoms in this host.

scholarly journals Historical Perspectives, Management, and Current Research of Citrus HLB in Guangdong Province of China, Where the Disease has been Endemic for Over a Hundred Years

2018 ◽  
Vol 108 (11) ◽  
pp. 1224-1236 ◽  
Author(s):  
Zheng Zheng ◽  
Jianchi Chen ◽  
Xiaoling Deng
Keyword(s):  
Southern China ◽  
Candidatus Liberibacter Asiaticus ◽  
Sequencing Technology ◽  
Next Generation Sequencing Technology ◽  
Historical Perspectives ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Generation Sequencing

Citrus huanglongbing (HLB) is a highly destructive disease currently threatening citrus production worldwide. In China, the disease is exclusively associated with ‘Candidatus Liberibacter asiaticus’, a nonculturable proteobacterium. HLB was observed in Guangdong of China over a hundred years ago. Researchers and citrus growers have been battling with the disease through vigorous research and have exercised various control practices. Much of the early work was not well known outside China. This review is intended to fill in gaps of historical information by reviewing selected literature records. Along the way, the HLB system within southern China was evaluated. Emphases were on comparison of symptomatology, evolution of etiology, control practices, and impacts of using next-generation sequencing technology for ‘Ca. L. asiaticus’ research and detection.

scholarly journals Latency and Persistence of ‘Candidatus Liberibacter asiaticus’ in Its Psyllid Vector, Diaphorina citri (Hemiptera: Liviidae)

2017 ◽  
Vol 107 (3) ◽  
pp. 264-272 ◽  
Author(s):  
Maria Cristina Canale ◽  
Arthur Fernando Tomaseto ◽  
Marineia de Lara Haddad ◽  
Helvécio Della Coletta-Filho ◽  
João Roberto Spotti Lopes
Keyword(s):  
Latent Period ◽  
Acquisition Time ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Old Adults ◽  
Sequential Inoculation ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Series Of Experiments

Although ‘Candidatus Liberibacter asiaticus’ (Las) is a major pathogen associated with citrus huanglongbing (HLB), some characteristics of transmission by the psyllid vector Diaphorina citri are not fully understood. We examined the latent period and persistence of transmission of Las by D. citri in a series of experiments at 25°C, in which third-instar psyllid nymphs and 1-week-old adults were confined on infected citrus for an acquisition access period (AAP), and submitted to sequential inoculation access periods (IAPs) on healthy citrus seedlings. The median latent period (LP50, i.e., acquisition time after which 50% of the individuals can inoculate) of 16.8 and 17.8 days for psyllids that acquired Las as nymphs and adults, respectively, was determined by transferring single individuals in 48-h IAPs. Inoculation events were intermittent and randomly distributed over the IAPs, but were more frequent after acquisition by nymphs. A minimum latent period of 7 to 10 days was observed by transferring groups of 10 psyllids in 48-h IAPs, after a 96-h AAP by nymphs. Psyllids transmitted for up to 5 weeks, when submitted to sequential 1-week IAPs after a 14-day AAP as nymphs. The long latent period and persistence of transmission are indirect evidences of circulative propagation of Las in D. citri.

scholarly journals Low Incidence of ‘Candidatus Liberibacter asiaticus’ in Murraya paniculata and Associated Diaphorina citri

Plant Disease ◽  
2012 ◽  
Vol 96 (6) ◽  
pp. 827-832 ◽  
Author(s):  
Abigail J. Walter ◽  
David G. Hall ◽  
Yong Ping Duan
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Disease Epidemiology ◽  
Citrus Groves ◽  
Murraya Paniculata ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Low Incidence ◽  
A Minor

Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. ‘Candidatus Liberibacter asiaticus’ is the prevalent species of three HLB-associated Liberibacter spp., which is vectored by the psyllid Diaphorina citri. The vector and the bacteria have host plants outside the genus Citrus, and these plants have the potential to affect disease epidemiology within citrus groves. Murraya paniculata could be especially problematic because it is a popular ornamental plant and a host of both psyllid and bacteria. We conducted a year-long survey of eight urban plantings of M. paniculata in east-central Florida to characterize ‘Ca. L. asiaticus’ infection rates in plants and associated psyllids. Using sensitive quantitative polymerase chain reaction (qPCR) primers targeting two prophage genes of ‘Ca. L. asiaticus’, we found infection to be extremely low: less than 1% of psyllids and 1.8% of plants. With qPCR primers targeting ‘Ca. L. asiaticus’ 16S rDNA, none of the plants and only one psyllid were ‘Ca. L. asiaticus’-positive. Therefore, the titer of ‘Ca. L. asiaticus’ is low in M. paniculata and associated psyllids. These results suggest that urban plantings of M. paniculata may serve as a minor source of ‘Ca. L. asiaticus’ inoculum.

scholarly journals Development on Infected Citrus over Generations Increases Vector Infection by ‘Candidatus Liberibacter Asiaticus in Diaphorina citri’

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 469
Author(s):  
Inaiara de Souza Pacheco ◽  
Diogo Manzano Galdeano ◽  
João Roberto Spotti Lopes ◽  
Marcos Antonio Machado
Keyword(s):  
Management Strategies ◽  
Fourth Generation ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Citrus Orchards ◽  
Vector Efficiency ◽  
Control And Eradication

‘Candidatus Liberibacter asiaticus’ (CLas) is a major causal agent of citrus Huanglongbing (HLB), which is transmitted by Asian citrus psyllid (ACP), Diaphorina citri, causing severe losses in various regions of the world. Vector efficiency is higher when acquisition occurs by ACP immature stages and over longer feeding periods. In this context, our goal was to evaluate the progression of CLas population and infection rate over four ACP generations that continuously developed on infected citrus plants. We showed that the frequency of CLas-positive adult samples increased from 42% in the parental generation to 100% in the fourth generation developing on CLas-infected citrus. The bacterial population in the vector also increased over generations. This information reinforces the importance of HLB management strategies, such as vector control and eradication of diseased citrus trees, to avoid the development of CLas-infected ACP generations with higher bacterial loads and, likely, a higher probability of spreading the pathogen in citrus orchards.

scholarly journals Genome Sequence Resource of “Candidatus Liberibacter asiaticus” strain Myan16 from Myanmar

Plant Disease ◽  
2020 ◽  
Author(s):  
Yongqin Zheng ◽  
jun guo ◽  
Xiaoling Deng ◽  
Zheng Zheng
Keyword(s):  
Genome Sequence ◽  
Draft Genome ◽  
Sequence Database ◽  
Candidatus Liberibacter Asiaticus ◽  
Genome Sequence Database ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus

“Candidatus Liberibacter asiaticus” (CaLas), an uncultured α-proteobacterium, is associated with citrus Huanglongbing (HLB, yellow shoot disease), a destructive disease threatening citrus production worldwide. Here, we reported the draft genome sequence of CaLas strain Myan16 from a HLB-affected lime tree in Myitkyina, Kachin State, Myanmar. The strain Myan16 genome is 1,229,102 bp with an average G+C content of 36.4%, along with a circular prophage: P-Myan16-2 (36,303 bp, Type 2). This is the first genome sequence of CaLas strain from Myanmar, which will enrich the current CaLas genome sequence database and facilitate HLB epidemiology research in Asia and world.

scholarly journals Genome Sequence Resources of Two ‘Candidatus Liberibacter asiaticus’ Strains from Pakistan

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2048-2050 ◽  
Author(s):  
Kehong Liu ◽  
Sagheer Atta ◽  
Xuejin Cui ◽  
Chunhua Zeng ◽  
Jianchi Chen ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Gc Content ◽  
Sequence Database ◽  
Candidatus Liberibacter Asiaticus ◽  
Genome Sequences ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus

‘Candidatus Liberibacter asiaticus’ (CLas) is an unculturable, phloem-restricted αProteobacteria, associated with citrus Huanglongbing (HLB), which is one of the most destructive diseases in citrus production worldwide. Here, we present the genome sequences of CLas strains PA19 and PA20 from HLB-affected kinnow trees in Multan, Punjab Province, Pakistan. The CLas genomes of PA19 and PA20 comprise 1,224,156 bp and 1,226,225 bp, respectively, with an average GC content of 36.4%. Both harbored the Type 2 prophage. In this study, we report two CLas genomes from Pakistan, which extends the sequence database of CLas and will contribute to CLas biology and HLB management.

scholarly journals Temporal Progression of ‘Candidatus Liberibacter asiaticus’ Infection in Citrus and Acquisition Efficiency by Diaphorina citri

2014 ◽  
Vol 104 (4) ◽  
pp. 416-421 ◽  
Author(s):  
Helvecio D. Coletta-Filho ◽  
Matthew P. Daugherty ◽  
Cléderson Ferreira ◽  
João R. S. Lopes
Keyword(s):  
Transmission Efficiency ◽  
Management Tool ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Infection Level ◽  
Plant Infection ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Asymptomatic Phase

Over the last decade, the plant disease huanglongbing (HLB) has emerged as a primary threat to citrus production worldwide. HLB is associated with infection by phloem-limited bacteria (‘Candidatus Liberibacter’ spp.) that are transmitted by the Asian citrus psyllid, Diaphorina citri. Transmission efficiency varies with vector-related aspects (e.g., developmental stage and feeding periods) but there is no information on the effects of host–pathogen interactions. Here, acquisition efficiency of ‘Candidatus Liberibacter asiaticus’ by D. citri was evaluated in relation to temporal progression of infection and pathogen titer in citrus. We graft inoculated sweet orange trees with ‘Ca. L. asiaticus’; then, at different times after inoculation, we inspected plants for HLB symptoms, measured bacterial infection levels (i.e., titer or concentration) in plants, and measured acquisition by psyllid adults that were confined on the trees. Plant infection levels increased rapidly over time, saturating at uniformly high levels (≈108 copy number of 16S ribosomal DNA/g of plant tissue) near 200 days after inoculation—the same time at which all infected trees first showed disease symptoms. Pathogen acquisition by vectors was positively associated with plant infection level and time since inoculation, with acquisition occurring as early as the first measurement, at 60 days after inoculation. These results suggest that there is ample potential for psyllids to acquire the pathogen from trees during the asymptomatic phase of infection. If so, this could limit the effectiveness of tree rouging as a disease management tool and would likely explain the rapid spread observed for this disease in the field.

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