scholarly journals Steam Explosion (STEX) of Citrus × Poncirus Hybrids with Exceptional Tolerance to Candidatus Liberibacter Asiaticus (CLas) as Useful Sources of Volatiles and Other Commercial Products

Biology ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1285
Author(s):  
Christina Dorado ◽  
Kim D. Bowman ◽  
Randall G. Cameron ◽  
John A. Manthey ◽  
Jinhe Bai ◽  
...  
Keyword(s):  
Steam Explosion ◽  
Citrus Fruit ◽  
Poncirus Trifoliata ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Florida Citrus ◽  
Alternative Feedstock ◽  
Citrus Hybrids

Florida citrus production has declined 75% due to Huanglongbing (HLB), a disease caused by the pathogenic bacterium Candidatus Liberibacter asiaticus (CLas). Methods to combat CLas are costly and only partially effective. The cross-compatible species Poncirus trifoliata and some of its hybrids are known to be highly tolerant to CLas, and thus can potentially serve as an alternative feedstock for many citrus products. To further investigate the commercial potential of citrus hybrids, three citrus hybrids, US-802, US-897, and US-942, were studied for their potential as feedstocks for citrus co-products using steam explosion (STEX) followed by water extraction. Up to 93% of sugars were recovered. US-897 and US-942 have similar volatile profiles to that of the commercial citrus fruit types and as much as 85% of these volatiles could be recovered. Approximately 80% of the pectic hydrocolloids present in all three hybrids could be obtained in water washes of STEX material. Of the phenolics identified, the flavanone glycosides, i.e., naringin, neohesperidin, and poncirin were the most abundant quantitatively in these hybrids. The ability to extract a large percentage of these compounds, along with their inherent values, make US-802, US-897, and US-942 potentially viable feedstock sources for citrus co-products in the current HLB-blighted environment.

scholarly journals Susceptibility of Sixteen Citrus Genotypes to ‘Candidatus Liberibacter asiaticus’

Plant Disease ◽  
2016 ◽  
Vol 100 (6) ◽  
pp. 1080-1086 ◽  
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.

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 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.

Two unique prophages of “Candidatus Liberibacter asiaticus” strains from Pakistan

2020 ◽  
Author(s):  
Xuejin Cui ◽  
Kehong Liu ◽  
Sagheer Atta ◽  
Chunhua Zeng ◽  
chang yong zhou ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Genomic Diversity ◽  
Early Gene ◽  
Gene Region ◽  
Late Gene ◽  
Candidatus Liberibacter Asiaticus ◽  
High Sequence Similarity ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

“Candidatus Liberibacter asiaticus” (CLas) is a pathogen causing Huanglongbing (HLB, yellow shoot disease), which is highly destructive to citrus production. The CLas strains harbor prophages. We identified two unique prophages, designated as P-PA19-1 and P-PA19-2, in CLas strain PA19 from Pakistan using next-generation sequencing (NGS) analysis. P-PA19-1 prophage has high sequence similarity (Identity: 78.23%) at the early-gene region of prophage SC1 (Type 1) but it is significantly divergent in the late-gene region (Identity: 62.03%). P-PA19-2 was highly similar to SC2 (Type 2) in the late gene region (Identity: 97.96%), and also in the early gene region except for a deletion of a 7,179 bp nucleotide sequence that contains a CRISPR/cas system in SC2. Both P-PA19-1 and P-PA19-2 had circular plasmid forms, and only P-PA19-2 was found integrated in the PA19 chromosome. The two new prophages were only found in Pakistani samples. Identification of prophages enhances our understanding of CLas genomic diversity and also the biology and evolution of CLas prophages.

scholarly journals Guangdong and Florida Populations of ‘Candidatus Liberibacter asiaticus’ Distinguished by a Genomic Locus with Short Tandem Repeats

2010 ◽  
Vol 100 (6) ◽  
pp. 567-572 ◽  
Author(s):  
J. Chen ◽  
X. Deng ◽  
X. Sun ◽  
D. Jones ◽  
M. Irey ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Candidatus Liberibacter Asiaticus ◽  
Bacterial Strains ◽  
Genomic Locus ◽  
Global Epidemiology ◽  
Geographical Regions ◽  
The World ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Huanglongbing (HLB) (yellow shoot disease) is a highly destructive disease that threatens citrus production worldwide. The disease was first observed in Guangdong, P.R. China, over 100 years ago, and was found in Florida, United States, in 2005. ‘Candidatus Liberibacter asiaticus’ has been associated with HLB in many citrus-growing regions around the world, including Guangdong and Florida. The global epidemiology of HLB, as well as management of the disease, relies on knowledge of ‘Ca. L. asiaticus’ populations in different geographical regions around the world. In this study, we identified a genetic marker containing small tandem repeats in the genome of ‘Ca. L. asiaticus’ and comparatively analyzed the tandem repeat numbers (TRNs) in ‘Ca. L. asiaticus’ populations from Guangdong and Florida. Analyses of TRNs showed that the bacterial population in Guangdong was different from that in Florida. The Guangdong population consisted predominately of strains with a TRN of 7 (TRN7) at a frequency of 47.6%. The Florida population consisted predominately of strains with a TRN of 5 (TRN5) at a frequency of 84.4%. TRNs ranged from 3 to 16. The apparent absence of TRNs of 9, 10, 11, and 12 separated the bacterial strains into two groups: TRNs < 10 (TRN<10) and TRNs > 10 (TRN>10). In Florida, TRN<10 strains (103/109, or 94.5%) were widely distributed in all HLB-affected counties. TRN>10 strains (6/109, or 5.5%) were found in central Florida. This is the first report documenting the differentiation of ‘Ca. L. asiaticus’ populations between Asia and North America and the possible presence of two differentially distributed genotypes of ‘Ca. L. asiaticus’ in Florida.

scholarly journals Genome Sequence Resource of ‘Candidatus Liberibacter asiaticus’ strain 9PA From Brazil

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 199-201
Author(s):  
P. A. Silva ◽  
J. Huang ◽  
N. A. Wulff ◽  
Z. Zheng ◽  
R. Krugner ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Sweet Orange ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
And Control

‘Candidatus Liberibacter asiaticus’, an unculturable α-proteobacterium, is associated with citrus huanglongbing (HLB), a devastating disease threatening citrus production in Brazil and worldwide. In this study, a draft whole-genome sequence of ‘Ca. L. asiaticus’ strain 9PA from a sweet orange (cultivar Pera) tree collected in São Paulo State, Brazil, is reported. The 9PA genome is 1,231,881 bp, including two prophages, with G+C content of 36.7%. This is the first report of a whole-genome sequence of ‘Ca. L. asiaticus’ from Brazil or South America. The 9PA genome sequence will enrich ‘Ca. L. asiaticus’ genome resources and facilitate HLB research and control in Brazil and the world.

Assessment of the effect of thermotherapy on Candidatus Liberibacter asiaticus viability in woody tissue of citrus via graft-based assay and RNA-assay

2020 ◽  
Author(s):  
Naweena Thapa ◽  
Michelle D. Danyluk ◽  
Kayla Michele Gerberich ◽  
Evan Grier Johnson ◽  
Megan M. Dewdney
Keyword(s):  
Gene Expression Analysis ◽  
Rna Extraction ◽  
Candidatus Liberibacter Asiaticus ◽  
Short Term ◽  
Woody Tissue ◽  
Viability Assay ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Term Field

By 2019, Florida’s citrus production declined over 70%, mostly due to Huanglongbing (HLB), caused by the bacterium Candidatus Liberibacter asiaticus (CLas). Thermotherapy on HLB-affected trees was proposed to maintain short-term field productivity. Thermotherapy could eliminate HLB from affected branches was hypothesized, therefore objectives were to show which time-temperature combinations eliminated CLas from woody tissues. Valencia twigs collected from HLB-affected field trees were steam chamber treated at different time-temperature combinations [50°C for 60 s, 55°C for 0 s, 30 s, 60 s, 90 s, 120s, 60°C for 30 s, and untreated control (UTC)]. Three independent repetitions of 13 branches/treatment were used, grafted onto rootstocks, and tested for CLas after 6, 9, and 12 months. For the RNA-based CLas viability assay, 3 branches/treatment were treated, and bark samples peeled for RNA extraction and subsequent gene expression analysis. From grafting study, at 12 months after grafting, four trees grafted with twigs treated at 55°C for 90 s or 55°C for 120 s had detectable CLas DNA. In those individuals, titers were significantly lower (P ≤ 0.0001) and could be degrading DNA remnants. Additionally, CLas 16S rRNA expression decreased significantly (P ≤ 0.0001) at 55°C for 90 s, 55°C for 120 s, and 60°C for 30 s (3.4-, 3.4- and 2.3-fold change, respectively) 5 days post-treatment. Heat injury, not total CLas kill, could explain limited transcriptional activity changes; however, failed recovery and eventual CLas death resulted in no CLas detection in most of the grafted trees treated with the highest temperatures or longest durations.

scholarly journals Understanding Citrus Greening Disease and Its Possible Management Strategies in Nepal

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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