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Multilocus microsatellite analysis of 'Candidatus Liberibacter asiaticus' associated with citrus Huanglongbing worldwide.

Islam MS, Glynn JM, Bai Y, Duan YP, Coletta-Filho HD, Kuruba G, Civerolo EL, Lin H - BMC Microbiol. (2012)

Bottom Line: HLB-associated Liberibacters have spread to North America and South America in recent years.Our results identified three major genetic groups of 'Ca.L. asiaticus'.

View Article: PubMed Central - HTML - PubMed

Affiliation: USDA-ARS San Joaquin Valley Agricultural Research Science Center, Parlier, CA 93648, USA.

ABSTRACT

Background: Huanglongbing (HLB) is one of the most destructive citrus diseases in the world. The disease is associated with the presence of a fastidious, phloem-limited α- proteobacterium, 'Candidatus Liberibacter asiaticus', 'Ca. Liberibacter africanus' or 'Ca. Liberibacter americanus'. HLB-associated Liberibacters have spread to North America and South America in recent years. While the causal agents of HLB have been putatively identified, information regarding the worldwide population structure and epidemiological relationships for 'Ca. L. asiaticus' is limited. The availability of the 'Ca. L. asiaticus' genome sequence has facilitated development of molecular markers from this bacterium. The objectives of this study were to develop microsatellite markers and conduct genetic analyses of 'Ca. L. asiaticus' from a worldwide collection. Two hundred eighty seven isolates from USA (Florida), Brazil, China, India, Cambodia, Vietnam, Taiwan, Thailand, and Japan were analyzed.

Results: A panel of seven polymorphic microsatellite markers was developed for 'Ca. L. asiaticus'. Microsatellite analyses across the samples showed that the genetic diversity of 'Ca. L. asiaticus' is higher in Asia than Americas. UPGMA and STRUCTURE analyses identified three major genetic groups worldwide. Isolates from India were genetically distinct. East-southeast Asian and Brazilian isolates were generally included in the same group; a few members of this group were found in Florida, but the majority of the isolates from Florida were clustered separately. eBURST analysis predicted three founder haplotypes, which may have given rise to three groups worldwide.

Conclusions: Our results identified three major genetic groups of 'Ca. L. asiaticus' worldwide. Isolates from Brazil showed similar genetic makeup with east-southeast Asian dominant group, suggesting the possibility of a common origin. However, most of the isolates recovered from Florida were clustered in a separate group. While the sources of the dominant 'Ca. L. asiaticus' in Florida were not clearly understood, the less-pervasive groups may have been introduced directly from Asia or via Brazil. Notably, the recent outbreak of HLB in Florida probably occurred through multiple introductions. Microsatellite markers developed in this study provide adequate discriminatory power for the identification and differentiation of closely-related isolates, as well as for genetic studies of 'Ca. L. asiaticus'.

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Related in: MedlinePlus

Network diagram (based on nearly identical haplotypes that differed by two loci) from eBURST analysis. Solid blue circles in the diagram indicate three predicted founder haplotypes: China (Haplotye-108), Brazil (Haplotype-48) and India (Haplotype-46). A primary network was observed between haplotype-103 and 107 (Florida), and predicted founder haplotypes in China, and between haplotype-51 (Florida) with predicted founder haplotypes in Brazil, suggesting two separate introductions of 'Ca. L. asiaticus' into Florida.
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Figure 3: Network diagram (based on nearly identical haplotypes that differed by two loci) from eBURST analysis. Solid blue circles in the diagram indicate three predicted founder haplotypes: China (Haplotye-108), Brazil (Haplotype-48) and India (Haplotype-46). A primary network was observed between haplotype-103 and 107 (Florida), and predicted founder haplotypes in China, and between haplotype-51 (Florida) with predicted founder haplotypes in Brazil, suggesting two separate introductions of 'Ca. L. asiaticus' into Florida.

Mentions: eBURST analysis with user-defined criteria (based on the analysis of haplotypes that shared identical genotypes for at least 5 of the 7 loci) predicted three founder haplotypes: haplotype-108 (Nanning, Guangxi province, China), haplotype-48 (São Paulo, Brazil) and haplotype-46 (Tirupati District, Andhra Pradesh, India) (Additiontal file 1 and Figure 3). The diagram generated by eBURST showed a primary network between haplotype-103 and 107 (Collier County, Florida) and predicted founder haplotype in China. A primary network was also identified with haplotype-51 (Pasco County, Florida) and the second predicted founder haplotype in Brazil. Haplotype-46 from Tirupati District, Andhra Pradesh, India) was predicted to be the third founder and hypothesized to be the founder haplotype of 'Ca. L. asiaticus' in India.


Multilocus microsatellite analysis of 'Candidatus Liberibacter asiaticus' associated with citrus Huanglongbing worldwide.

Islam MS, Glynn JM, Bai Y, Duan YP, Coletta-Filho HD, Kuruba G, Civerolo EL, Lin H - BMC Microbiol. (2012)

Network diagram (based on nearly identical haplotypes that differed by two loci) from eBURST analysis. Solid blue circles in the diagram indicate three predicted founder haplotypes: China (Haplotye-108), Brazil (Haplotype-48) and India (Haplotype-46). A primary network was observed between haplotype-103 and 107 (Florida), and predicted founder haplotypes in China, and between haplotype-51 (Florida) with predicted founder haplotypes in Brazil, suggesting two separate introductions of 'Ca. L. asiaticus' into Florida.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368738&req=5

Figure 3: Network diagram (based on nearly identical haplotypes that differed by two loci) from eBURST analysis. Solid blue circles in the diagram indicate three predicted founder haplotypes: China (Haplotye-108), Brazil (Haplotype-48) and India (Haplotype-46). A primary network was observed between haplotype-103 and 107 (Florida), and predicted founder haplotypes in China, and between haplotype-51 (Florida) with predicted founder haplotypes in Brazil, suggesting two separate introductions of 'Ca. L. asiaticus' into Florida.
Mentions: eBURST analysis with user-defined criteria (based on the analysis of haplotypes that shared identical genotypes for at least 5 of the 7 loci) predicted three founder haplotypes: haplotype-108 (Nanning, Guangxi province, China), haplotype-48 (São Paulo, Brazil) and haplotype-46 (Tirupati District, Andhra Pradesh, India) (Additiontal file 1 and Figure 3). The diagram generated by eBURST showed a primary network between haplotype-103 and 107 (Collier County, Florida) and predicted founder haplotype in China. A primary network was also identified with haplotype-51 (Pasco County, Florida) and the second predicted founder haplotype in Brazil. Haplotype-46 from Tirupati District, Andhra Pradesh, India) was predicted to be the third founder and hypothesized to be the founder haplotype of 'Ca. L. asiaticus' in India.

Bottom Line: HLB-associated Liberibacters have spread to North America and South America in recent years.Our results identified three major genetic groups of 'Ca.L. asiaticus'.

View Article: PubMed Central - HTML - PubMed

Affiliation: USDA-ARS San Joaquin Valley Agricultural Research Science Center, Parlier, CA 93648, USA.

ABSTRACT

Background: Huanglongbing (HLB) is one of the most destructive citrus diseases in the world. The disease is associated with the presence of a fastidious, phloem-limited α- proteobacterium, 'Candidatus Liberibacter asiaticus', 'Ca. Liberibacter africanus' or 'Ca. Liberibacter americanus'. HLB-associated Liberibacters have spread to North America and South America in recent years. While the causal agents of HLB have been putatively identified, information regarding the worldwide population structure and epidemiological relationships for 'Ca. L. asiaticus' is limited. The availability of the 'Ca. L. asiaticus' genome sequence has facilitated development of molecular markers from this bacterium. The objectives of this study were to develop microsatellite markers and conduct genetic analyses of 'Ca. L. asiaticus' from a worldwide collection. Two hundred eighty seven isolates from USA (Florida), Brazil, China, India, Cambodia, Vietnam, Taiwan, Thailand, and Japan were analyzed.

Results: A panel of seven polymorphic microsatellite markers was developed for 'Ca. L. asiaticus'. Microsatellite analyses across the samples showed that the genetic diversity of 'Ca. L. asiaticus' is higher in Asia than Americas. UPGMA and STRUCTURE analyses identified three major genetic groups worldwide. Isolates from India were genetically distinct. East-southeast Asian and Brazilian isolates were generally included in the same group; a few members of this group were found in Florida, but the majority of the isolates from Florida were clustered separately. eBURST analysis predicted three founder haplotypes, which may have given rise to three groups worldwide.

Conclusions: Our results identified three major genetic groups of 'Ca. L. asiaticus' worldwide. Isolates from Brazil showed similar genetic makeup with east-southeast Asian dominant group, suggesting the possibility of a common origin. However, most of the isolates recovered from Florida were clustered in a separate group. While the sources of the dominant 'Ca. L. asiaticus' in Florida were not clearly understood, the less-pervasive groups may have been introduced directly from Asia or via Brazil. Notably, the recent outbreak of HLB in Florida probably occurred through multiple introductions. Microsatellite markers developed in this study provide adequate discriminatory power for the identification and differentiation of closely-related isolates, as well as for genetic studies of 'Ca. L. asiaticus'.

Show MeSH
Related in: MedlinePlus