scholarly journals PHLOEM PROMOTERS IN TRANSGENIC SWEET ORANGE ARE DIFFERENTIALLY TRIGGERED BY Candidatus Liberibacter asiaticus

2017 ◽  
Vol 39 (3) ◽  
Author(s):  
LUZIA YURIKO MIYATA ◽  
RICARDO HARAKAVA ◽  
LÍSIA BORGES ATTÍLIO ◽  
BEATRIZ MADALENA JANUZZI MENDES ◽  
JOÃO ROBERTO SPOTTI LOPES ◽  
...  
Keyword(s):  
Reporter Gene ◽  
Citrus Sinensis ◽  
Transgene Expression ◽  
Sweet Orange ◽  
Candidatus Liberibacter Asiaticus ◽  
Specific Expression ◽  
Gus Reporter ◽  
Uida Expression ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

ABSTRACT The use of promoters preferentially expressed in specific plant tissues is a desirable strategy to search for resistance for pathogens that colonize these tissues. The bacterium Candidatus Liberibacter asiaticus (Las), associated with huanglongbing disease (HLB) of citrus, colonizes phloem vessels. Some promoters, besides conferring tissue-specific expression, can also respond to the presence of the pathogen. The objective of the present study was to verify if the presence of Las could modulate the activation of the phloem-specific promoters AtPP2 (Arabidopsis thaliana phloem protein 2), AtSUC2 (A. thaliana sucrose transporter 2) and CsPP2 ( pCitrus phloemrotein 2), known to be expressed in Citrus sinensis phloem. ‘Hamlin’ sweet orange plants (Citrus sinensis L. Osbeck) transformed with the uidA (GUS) reporter gene under the control of AtPP2, AtSUC2 and CsPP2 promoters were infected to evaluate the interdependence between transgene expression and the concentration of Las. Plants were inoculated with Las by Diaphorina citri and eighteen months later, bacterial concentration and uidA expression were determined by qPCR and RT-qPCR, respectively. Reporter gene expression driven by AtSUC2 promoter was strongly and positively correlated with Las concentration. Therefore, this promoter combines desirable features of both tissue-specificity and pathogen-inducibility for the production of transgenic plants tolerant to Las.

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

2011 ◽  
Vol 12 (1) ◽  
pp. 24 ◽  
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.

scholarly journals Reaction of sweet orange cultivars expressing the attacin A gene to 'Candidatus Liberibacter asiaticus' infection

2013 ◽  
Vol 48 (11) ◽  
pp. 1440-1448 ◽  
Author(s):  
Rafaella Teles Arantes Felipe ◽  
Francisco de Assis Alves Mourão Filho ◽  
Silvio Aparecido Lopes ◽  
Beatriz Madalena Januzzi Mendes ◽  
Maurel Behling ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Pcr Analysis ◽  
Candidatus Liberibacter Asiaticus ◽  
Randomized Design ◽  
Transgenic Lines ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain ◽  
Attacin A ◽  
Leaf Symptoms

The objective of this work was to evaluate the reaction of four sweet orange cultivars expressing the attacin A gene to 'Candidatus Liberibacter asiaticus' (Las) infection, a bacterium associated to huanglongbing (HLB) disease. Transgenic sweet orange plants of Hamlin, Natal, Pêra, and Valência cultivars, as well as nontransgenic controls received inocula by grafting budwood sections of HLB-infected branches. Disease progression was evaluated through observations of leaf symptoms and by polymerase chain reaction (PCR) analysis, eight months after inoculation. A completely randomized design was used, with four experiments (one for each cultivar) performed simultaneously. Bacteria title was estimated by quantitative PCR (qPCR). HLB symptoms and Las titers were present in nontransgenic and transgenic plants expressing the attacin A gene of the four sweet orange cultivars, eight months after bacteria inoculation. Five transgenic lines (transformation events) of 'Pêra' sweet orange expressing the attacin A gene have significantly lower Las titers in comparison with nontransgenic plants of this cultivar.

Comparative iTRAQ proteome and transcriptome analyses of sweet orange infected by “Candidatus Liberibacter asiaticus”

2011 ◽  
Vol 143 (3) ◽  
pp. 235-245 ◽  
Author(s):  
Jing Fan ◽  
Chunxian Chen ◽  
Qibin Yu ◽  
Ronald H. Brlansky ◽  
Zheng-Guo Li ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Transcriptome Analyses

scholarly journals Murraya paniculata and Swinglea glutinosa as Short-Term Transient Hosts of ‘Candidatus Liberibacter asiaticus’ and Implications for the Spread of Huanglongbing

2019 ◽  
Vol 109 (12) ◽  
pp. 2064-2073 ◽  
Author(s):  
Juan Camilo Cifuentes-Arenas ◽  
George Andrew Charles Beattie ◽  
Leandro Peña ◽  
Silvio Aparecido Lopes
Keyword(s):  
Sweet Orange ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Principal Vector ◽  
Dead End ◽  
Valencia Orange ◽  
Murraya Paniculata ◽  
Citrus Rootstock ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Murraya paniculata and Swinglea glutinosa are aurantioid hosts of the Asian citrus psyllid (ACP) Diaphorina citri, the principal vector of ‘Candidatus Liberibacter asiaticus’ (Las). Las is the pathogen associated with huanglongbing (HLB), the Asian form of which is the most devastating disease of Citrus species and cultivars (Rutaceae: Aurantioideae). M. paniculata is a common ornamental and S. glutinosa is grown as an ornamental, a citrus rootstock, and a hedgerow fence plant. Because of the uncertain status of these plants as reservoirs of Las, a series of cross-inoculation bioassays were carried out in different environments, using infected Valencia sweet orange (Citrus × aurantium) infected shoot tops as a source of inoculum and D. citri nymphs and adults reared on M. paniculata and S. glutinosa to inoculate pathogen-free Valencia orange plantlets. In contrast to sweet orange, Las was more unevenly distributed and reached much lower titers in M. paniculata and S. glutinosa. Infections in M. paniculata and S. glutinosa were also transient. Very few insects that successfully acquired Las from M. paniculata and S. glutinosa were able to transmit the pathogen to healthy citrus. Transmission rates were low from M. paniculata (1.0%) and S. glutinosa (2.0%) and occurred only in a controlled environment highly favorable to Las and ACP using 10-day-old adults that completed their life cycle on Las-positive plants. Our study showed that in HLB-endemic areas, M. paniculata and S. glutinosa can be deemed as epidemiologically dead-end hosts for Las and are not important alternative hosts of the pathogen for transmission to citrus. However, under a combination of conditions highly favorable to Las infection and transmission and in the absence of effective quarantine procedures, these plants could eventually serve as carriers of Las to regions currently free from HLB.

Prevalent transmission of 'Candidatus Liberibacter asiaticus’ over ‘Ca. Liberibacter americanus’ in a long-term controlled environment

2021 ◽  
Author(s):  
Maria Cândida de Godoy Gasparoto ◽  
Isabela Vescove Primiano ◽  
Renato Bassanezi ◽  
Silvia Afonseca Lourenço ◽  
Luiz Montesino ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Citrus Orchards ◽  
Test Plants

In Brazil, citrus huanglongbing (HLB) is associated with ‘Candidatus Liberibacter americanus’ (CLam) and ‘Ca. Liberibacter asiaticus’ (CLas). However, there are few studies about HLB epidemiology when both Liberibacter spp. and its insect vector, the Asian citrus psyllid (ACP, Diaphorina citri), are present. The objective of this work was to compare the transmission of HLB by ACP when both CLam and CLas are present as primary inoculum. Two experiments were performed under screenhouse conditions from April 2008 to January 2012 (experiment 1) and from February 2011 to December 2015 (experiment 2). The experiments were carried out with sweet orange plants infected with CLam or CLas as inoculum source surrounded by sweet orange healthy plants. One hundred Liberibacter-free adult psyllids were monthly confined to the source of inoculum plants for 7 days with subsequent free movement inside the screenhouse. Fortnightly, nymphs and adults of psyllids were monitored. Psyllid and leaf samples were collected periodically for Liberibacter detection by PCR or qPCR. CLas was detected more frequently than CLam in both psyllid and leaf samples. No mixed infections were detected in the psyllids. A clear prevalence of CLas over CLam was observed in both experiments. The final HLB incidences were 16.7 and 14.5% of Liberibacter-positive test plants, and CLas was detected in 92.3 and 93.1% of these infected plants. Mixed infection was observed only in 3.8% of infected test plants in experiment 1. These results endorse the shift in the prevalence of CLam to CLas observed in citrus orchards of São Paulo, Brazil.

scholarly journals Ultrastructural Changes and Putative Phage Particles Observed in Sweet Orange Leaves Infected with ‘Candidatus Liberibacter asiaticus’

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 320-324 ◽  
Author(s):  
S. M. Fu ◽  
John Hartung ◽  
C. Y. Zhou ◽  
H. N. Su ◽  
J. Tan ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Light And Electron Microscopy ◽  
Ultrastructural Changes ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Orange Trees ◽  
First Time ◽  
Citrus Disease ◽  
Putative Phage

Huanglongbing (HLB), also known as citrus greening, is currently the most destructive citrus disease. Anatomical analyses of HLB-affected sweet orange were carried out by light and electron microscopy. As compared with healthy citrus, the phloem plasmodesmata were plugged with callose, and in some samples the phloem was collapsed. Chloroplast structures were deformed. Prophage sequences occupy a significant portion of the genome of ‘Candidatus Liberibacter asiaticus’ and have been used to distinguish strains from Yunnan and Guangdong provinces in China and Florida. Interestingly, a large number of possible putative phage particles were observed attached on the surface of ‘Ca. L. asiaticus’ cells in plants inoculated with strain FJ3 from Fujian Province, China. Phage particles have been observed previously only in periwinkle plants artificially inoculated in Florida with ‘Ca. L. asiaticus’ that carried the SC1-type prophage. PCR assays verified the presence of the SC1-type prophage sequences previously described from this bacterium in Florida in the FJ3 isolate. This is the first time that suspected phage particles have been observed in sweet orange trees infected with ‘Ca. L. asiaticus.’

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