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Poster: Biology & Disease Mgmt: Bacteriology


Insights from comparative analyses between the genomes of two model strains of the cucurbit pathogenic bacterium Acidovorax citrulli
S. BURDMAN (1), N. Eckshtain-Levi (2), D. Shkedy (3), M. Gershovits (3), G. Mateus da Silva (4), D. Tamir-Ariel (1), R. Walcott (4), T. Pupko (3) (1) The Hebrew University of Jerusalem, Israel; (2) The Hebrew University of Jerusalem , Israel; (3) Tel Aviv

Bacterial fruit blotch (BFB) of cucurbits, caused by Acidovorax citrulli (Ac), has been responsible for serious economic losses in watermelon and melon production worldwide. Ac strains are divided into two main groups based on genetic traits. While group I strains have been mainly isolated from melon, most group II strains were isolated from watermelon. The genome sequence of the group II model strain AAC00-1 is available since 2007. We recently sequenced the genome of the group I model strain M6. The M6 genome is 4.85 Mb in length, which is approximately 500 Kb shorter than that of AAC00-1. Comparative analysis revealed this size difference is mainly explained by eight AAC00-1 genomic regions (FAs; for fragments of AAC00-1), ranging from ~35 to 120 Kb and distributed throughout the AAC00-1 genome. The FAs are absent in the M6 genome. While AAC00-1 possesses over 500 open reading frames (ORFs) that are absent in M6, only about 120 M6 ORFs are absent in AAC00-1. Coverage analyses with draft genomes of other strains support the notion that significant portions of the FAs are discriminatory between groups I and II. Moreover, GC content, effective number of codon values’ and COG analyses support these FAs were introduced into group II strains by horizontal gene transfer. This study provides the first comprehensive genome comparison between the two major groups of Ac. Further investigation is needed to sharpen the distinctive genetic markers of the two groups.