Prevalence of Candidatus Liberibacter spp. in HLB-diseased Citrus Plants in São Paulo State, Brazil

Coletta-Filho, H. D.; Carlos, Eduardo Fermino; Lotto, L. L.; Luciane, F. C.; Alves, K. C. S.; Pereira, Murilo Anderson; Machado, Marcos Antônio

doi:10.5070/c57zg8d1v4

Cited by 4 publications

(1 citation statement)

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“…HLB can be carried and spread by insect psyllids, such as Trioza erytreae in Africa and Diaphorina citri in America and Asia, or it can be spread by grafting ( Reynaud et al, 2022 ). Although all three species can cause HLB, Las is most frequently identified in positive samples, and it has even outcompeted Lam in its native Brazil ( Coletta-Filho et al, 2010 ). Preventing HLB is a global concern as there are no widely implemented and sustainable cures available ( Alquézar et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Comparative genomics of the Liberibacter genus reveals widespread diversity in genomic content and positive selection history

Batarseh

Morales‐Cruz

et al. 2023

Front. Microbiol.

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‘Candidatus Liberibacter’ is a group of bacterial species that are obligate intracellular plant pathogens and cause Huanglongbing disease of citrus trees and Zebra Chip in potatoes. Here, we examined the extent of intra- and interspecific genetic diversity across the genus using comparative genomics. Our approach examined a wide set of Liberibacter genome sequences including five pathogenic species and one species not known to cause disease. By performing comparative genomics analyses, we sought to understand the evolutionary history of this genus and to identify genes or genome regions that may affect pathogenicity. With a set of 52 genomes, we performed comparative genomics, measured genome rearrangement, and completed statistical tests of positive selection. We explored markers of genetic diversity across the genus, such as average nucleotide identity across the whole genome. These analyses revealed the highest intraspecific diversity amongst the ‘Ca. Liberibacter solanacearum’ species, which also has the largest plant host range. We identified sets of core and accessory genes across the genus and within each species and measured the ratio of nonsynonymous to synonymous mutations (dN/dS) across genes. We identified ten genes with evidence of a history of positive selection in the Liberibacter genus, including genes in the Tad complex, which have been previously implicated as being highly divergent in the ‘Ca. L. capsica’ species based on high values of dN.

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Section: Introductionmentioning

confidence: 99%

Comparative genomics of the Liberibacter genus reveals widespread diversity in genomic content and positive selection history

Batarseh

Morales‐Cruz

et al. 2023

Front. Microbiol.

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Seasonal Variation in Populations of ‘Candidatus Liberibacter asiaticus’ in Citrus Trees in Paraná State, Brazil

et al. 2015

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Sauer, A.V., Zanutto, C.A., Nocchi, P.T.R., Machado, M.A., Bock, C.H, and Nunes, W.M.C. 201X. Seasonal variation in populations of 'Candidatus Liberibacter asiaticus' in citrus trees in Paraná state, Brazil. Plant Disease XX: xx-xx.Huanglongbing (HLB) is considered one of the most destructive diseases of citrus as the plants rapidly become unproductive, enter a decline and eventually die. HLB is caused by the phloem-limited bacterium 'Candidatus Liberibacter' spp. The objective of this study was to evaluate seasonal variation of the in planta population of 'Ca. Liberibacter asiaticus' (Las) in in the foliage of citrus trees in Brazil using real-time PCR (qPCR). Eleven plants (naturally infected, then screened) in the field with very mild and localized symptoms of HLB were confirmed to be Las-infected by conventional PCR, and the canopies were divided into four quadrants. The bacterial population in the trees was tested on a monthly basis for up to 20 months by quantifying Las DNA using qPCR Las-specific primers (As84F/As180R). The average C t (cycle threshold) values, which relate to Las titer, were analyzed using a mixed model. Significant differences were observed in C t values between seasons (F = 8.77, P = 0.0004), and abrupt changes were observed in C t values in different quadrants of the trees.Autumn had the lowest C t values, indicating the highest Las titer and is thus considered the best period to detect Las infection in citrus trees in southern Brazil. In addition to the seasonal changes in C t values, there was an initial decline in the C t value in the months following initial detection, the rate of decline slowing with time. Concomitant with the increase of the bacterial population in the host, there was an increase in severity of HLB symptoms in the trees over time (Spearman's rank correlation, r = -0.4083, P<0.0001). The

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Genome‐wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors

Thapa

Francesco

Trinh

et al. 2020

Molecular Plant Pathology

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Candidatus Liberibacter' species are insect-transmitted, phloem-limited α-Proteobacteria in the order of Rhizobiales. The citrus industry is facing significant challenges due to huanglongbing, associated with infection from 'Candidatus Liberibacter asiaticus' (Las). In order to gain greater insight into 'Ca. Liberibacter' biology and genetic diversity, we have performed genome sequencing and comparative analyses of diverse 'Ca. Liberibacter' species, including those that can infect citrus. Our phylogenetic analysis differentiates 'Ca. Liberibacter' species and Rhizobiales in separate clades and suggests stepwise evolution from a common ancestor splitting first into nonpathogenic Liberibacter crescens followed by diversification of pathogenic 'Ca. Liberibacter' species. Further analysis of Las genomes from different geographical locations revealed diversity among isolates from the United States. Our phylogenetic study also indicates multiple Las introduction events in California and spread of the pathogen from Florida to Texas. Texan Las isolates were closely related, while Florida and Asian isolates exhibited the most genetic variation. We have identified conserved Sec translocon (SEC)-dependent effectors likely involved in bacterial survival and virulence of Las and analysed their expression in their plant host (citrus) and insect vector (Diaphorina citri). Individual SEC-dependent effectors exhibited differential expression patterns between host and vector, indicating that Las uses its effector repertoire to differentially modulate diverse organisms. Collectively, this work provides insights into the evolution of 'Ca. Liberibacter' species, the introduction of Las in the United States and identifies promising Las targets for disease management. K E Y W O R D S 'Candidatus Liberibacter' sp., citrus greening disease, HLB, huanglongbing, phylogenomics, SEC effector | 717 THAPA eT Al.

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Prevalence of Candidatus Liberibacter spp. in HLB-diseased Citrus Plants in São Paulo State, Brazil

Cited by 4 publications

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Comparative genomics of the Liberibacter genus reveals widespread diversity in genomic content and positive selection history

Comparative genomics of the Liberibacter genus reveals widespread diversity in genomic content and positive selection history

Seasonal Variation in Populations of ‘Candidatus Liberibacter asiaticus’ in Citrus Trees in Paraná State, Brazil

Genome‐wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors

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