L. asiaticus’. Founder haplotypes were identified from China, Brazil, and India. Based on their position within the eBURST network, these founders are predicted to have given rise

to the three global genetic groups, consistent with prevailing theories of the geographic origins of HLB [1, 2, 4, 7]. While one founder type was predicted in Brazil, the similar genetic makeup of Brazilian and east-southeast Asian isolates suggest that this founder could have been introduced into Brazil from any of these Asian countries. Consistent with the STRUCTURE analysis, the eBURST diagram also predicted the introduction of ‘Ca. L. asiaticus’ into Florida citrus groves through at least two separate introduction events. While a primary network was detected between a founder haplotype from China and two unique haplotypes ISRIB cell line in Florida, clear differentiation was observed between most isolates from China and Florida by Bayesian clustering and UPGMA analyses. Differences between the dominant groups found in Florida and China were also reported in a recent study using a single VNTR locus [21]. It is uncertain whether

the dominant group of Florida isolates were introduced en masse or if a small population of nearly-identical ‘Ca. L. asiaticus’ haplotypes from China were introduced, evolved quickly, and established a large population. The recent discovery and rapid spread of HLB in Florida, along with wide distribution of dominant ‘Ca. L. asiaticus’ group observed in the present study suggests that isolates of this group have been directly

introduced from an unknown location. Another recent study also indicated eltoprazine that some isolates of ‘Ca. L. asiaticus’ from PLX3397 supplier Florida may have been introduced through two different events, and sources were unknown [21]. The analyses of microsatellites in the present study, however, suggest that the introduction of the less-dominant cluster was likely from a single source either Asia or Brazil. The low occurrence of less dominant group in some central counties in Florida suggests that the members of this group were perhaps introduced more recently (Figure 4). However, it is certainly plausible that these two haplotypes were introduced into Florida at nearly the same time. Isolates from one of the sources may have spread quickly due to selective advantage under a favorable set of biological or environmental conditions. Figure 4 Sample distribution of ‘ Candidatus Liberibacter asiaticus’ from 15 citrus-growing counties (gray highlighted) in Florida, USA. Green circles indicate the counties where only the dominant ‘Ca. L. asiaticus’ group were observed based on STRUCTURE analysis (green in Figure 2). Some isolates from Polk County (13), Pasco County (14) and Lake County (15) were see more included with the genetic group 2 (less dominant group) (see Figure 2). Our analysis showed that a dominant group of ‘Ca. L. asiaticus’ genotypes are widely distributed in south-central Florida (Figure 4).