Validation of 'variable number of tandem repeat'-based approach for examination of 'Candidatus Liberibacter asiaticus' diversity and its applications for the analysis of the pathogen populations in the areas of recent introduction.
Citrus greening (Huanglongbing, HLB) is one of the most destructive diseases of citrus worldwide. In South Asia HLB has been known for more than a century, while in Americas the disease was found relatively recently. HLB is associated with three species of 'Candidatus Liberibacter' among which 'Ca. Liberibacter asiaticus' (CLas) has most wide distribution. Recently, a number of studies identified different regions in the CLas genome with variable number of tandem repeats (VNTRs) that could be used for examination of CLas diversity. One of the objectives of the work presented here was to further validate the VNTR analysis-based approach by assessing the stability of these repeats upon multiplication of the pathogen in a host over an extended period of time and upon its passaging from a host to a host using CLas populations from Florida. Our results showed that the numbers of tandem repeats in the four loci tested display very distinguishable "signature profiles" for the two Florida-type CLas haplotype groups. Remarkably, the profiles do not change upon passage of the pathogen in citrus and psyllid hosts as well as after its presence within a host over a period of five years, suggesting that VNTR analysis-based approach represents a valid methodology for examination of the pathogen populations in various geographical regions. Interestingly, an extended analysis of CLas populations in different locations throughout Florida and in several countries in the Caribbean and Central America regions and in Mexico where the pathogen has been introduced recently demonstrated the dispersion of the same haplotypes of CLas. On the other hand, these CLas populations appeared to differ significantly from those obtained from locations where the disease has been present for a much longer time.
University of Florida, Department of Plant Pathology, Gainesville, Florida, United States of America ; Instituto Dominicano de Investigaciones Agropecuarias y Forestales, Santo Domingo, Dominican Republic.
Luis A
LA
Matos
Mark E
ME
Hilf
Jianchi
J
Chen
Svetlana Y
SY
Folimonova
D000818:Animals; D017691:Caribbean Region; D002489:Central America; D002957:Citrus / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D005431:Florida; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes; D006430:Hemiptera / Q000382:microbiology; D054884:Host-Pathogen Interactions; D008800:Mexico; D018598:Minisatellite Repeats / Q000235:genetics*; D010935:Plant Diseases / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011157:Population Dynamics; D012230:Rhizobiaceae / Q000235:genetics* / Q000502:physiology*
D004269:DNA, Bacterial