AUTHOR=Trantas Emmanouil A., Licciardello Grazia , Almeida Nalvo F., Witek Kamil , Strano Cinzia P., Duxbury Zane , Ververidis Filippos , Goumas Dimitrios E., Jones Jonathan D., Guttman David S., Catara Vittoria , Sarris Panagotis F.

TITLE=Comparative genomic analysis of multiple strains of two unusual plant pathogens: Pseudomonas corrugata and Pseudomonas mediterranea

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00811

DOI=10.3389/fmicb.2015.00811

ISSN=1664-302X

ABSTRACT=<p>The non-fluorescent pseudomonads, <italic>Pseudomonas corrugata</italic> (<italic>Pcor</italic>) and <italic>P. mediterranea</italic> (<italic>Pmed</italic>), are closely related species that cause pith necrosis, a disease of tomato that causes severe crop losses. However, they also show strong antagonistic effects against economically important pathogens, demonstrating their potential for utilization as biological control agents. In addition, their metabolic versatility makes them attractive for the production of commercial biomolecules and bioremediation. An extensive comparative genomics study is required to dissect the mechanisms that <italic>Pcor</italic> and <italic>Pmed</italic> employ to cause disease, prevent disease caused by other pathogens, and to mine their genomes for genes that encode proteins involved in commercially important chemical pathways. Here, we present the draft genomes of nine <italic>Pcor</italic> and <italic>Pmed</italic> strains from different geographical locations. This analysis covered significant genetic heterogeneity and allowed in-depth genomic comparison. All examined strains were able to trigger symptoms in tomato plants but not all induced a hypersensitive-like response in <italic>Nicotiana benthamiana</italic>. Genome-mining revealed the absence of type III secretion system and known type III effector-encoding genes from all examined <italic>Pcor</italic> and <italic>Pmed</italic> strains. The lack of a type III secretion system appears to be unique among the plant pathogenic pseudomonads. Several gene clusters coding for type VI secretion system were detected in all genomes. Genome-mining also revealed the presence of gene clusters for biosynthesis of siderophores, polyketides, non-ribosomal peptides, and hydrogen cyanide. A highly conserved quorum sensing system was detected in all strains, although species specific differences were observed. Our study provides the basis for in-depth investigations regarding the molecular mechanisms underlying virulence strategies in the battle between plants and microbes.</p>