Unique features of a Japanese 'Candidatus Liberibacter asiaticus' strain revealed by whole genome sequencing

PLoS One. 2014 Sep 2;9(9):e106109. doi: 10.1371/journal.pone.0106109. eCollection 2014.


Citrus greening (huanglongbing) is the most destructive disease of citrus worldwide. It is spread by citrus psyllids and is associated with phloem-limited bacteria of three species of α-Proteobacteria, namely, 'Candidatus Liberibacter asiaticus', 'Ca. L. americanus', and 'Ca. L. africanus'. Recent findings suggested that some Japanese strains lack the bacteriophage-type DNA polymerase region (DNA pol), in contrast to the Floridian psy62 strain. The whole genome sequence of the pol-negative 'Ca. L. asiaticus' Japanese isolate Ishi-1 was determined by metagenomic analysis of DNA extracted from 'Ca. L. asiaticus'-infected psyllids and leaf midribs. The 1.19-Mb genome has an average 36.32% GC content. Annotation revealed 13 operons encoding rRNA and 44 tRNA genes, but no typical bacterial pathogenesis-related genes were located within the genome, similar to the Floridian psy62 and Chinese gxpsy. In contrast to other 'Ca. L. asiaticus' strains, the genome of the Japanese Ishi-1 strain lacks a prophage-related region.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alphaproteobacteria / genetics*
  • Arginine / biosynthesis
  • Bacteriophages / genetics
  • Base Pairing
  • Base Sequence
  • Biosynthetic Pathways / genetics
  • Citrus / microbiology
  • DNA Replication
  • DNA-Directed DNA Polymerase / genetics
  • Genes, Bacterial
  • Genome, Bacterial / genetics*
  • Japan
  • Molecular Sequence Annotation
  • Molecular Sequence Data
  • Mutation / genetics
  • Plant Leaves / microbiology
  • Polymorphism, Single Nucleotide / genetics
  • Sequence Analysis, DNA / methods*


  • Arginine
  • DNA-Directed DNA Polymerase

Grant support

The National Agriculture and Food Research Organization Institute of Fruit Tree Science provided funding for this study. The grant number is 199998. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.