The kiwifruit emerging pathogen Pseudomonas syringae pv. actinidiae does not produce AHLs but possesses three luxR solos.
Pseudomonas syringae pv. actinidiae (Psa) is an emerging phytopathogen causing bacterial canker disease in kiwifruit plants worldwide. Quorum sensing (QS) gene regulation plays important roles in many different bacterial plant pathogens. In this study we analyzed the presence and possible role of N-acyl homoserine lactone (AHL) quorum sensing in Psa. It was established that Psa does not produce AHLs and that a typical complete LuxI/R QS system is absent in Psa strains. Psa however possesses three putative luxR solos designated here as PsaR1, PsaR2 and PsaR3. PsaR2 belongs to the sub-family of LuxR solos present in many plant associated bacteria (PAB) that binds and responds to yet unknown plant signal molecules. PsaR1 and PsaR3 are highly similar to LuxRs which bind AHLs and are part of the canonical LuxI/R AHL QS systems. Mutation in all the three luxR solos of Psa showed reduction of in planta survival and also showed additive effect if more than one solo was inactivated in double mutants. Gene promoter analysis revealed that the three solos are not auto-regulated and investigated their possible role in several bacterial phenotypes.
International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
Hitendra Kumar
HK
Patel
Research Centre for Fruit Crops, Agricultural Research Council, Roma, Italy.
Patrizia
P
Ferrante
Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, U.O.S di Trieste, Trieste, Italy.
Sonia
S
Covaceuszach
Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, U.O.S di Trieste, Trieste, Italy.
Doriano
D
Lamba
Research Centre for Fruit Crops, Agricultural Research Council, Roma, Italy ; Research Unit for Fruit Trees, Agricultural Research Council, Caserta, Italy.
Marco
M
Scortichini
International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
Vittorio
V
Venturi
D029042:Actinidia / Q000382:microbiology*; D054742:Acyl-Butyrolactones; D010935:Plant Diseases / Q000382:microbiology*; D044224:Pseudomonas syringae / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D054742:Acyl-Butyrolactones; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins