Gene Cloning and Characterization of luxR Transcriptional Regulator from Erwinia amylovora

Erwinia amylovora is a necrogenic phytopathogenic bacterium,the causal agent of fire blight in pear(Pyrus sorotina),apple(Malus domestica) and other members of the Rosaceae family,causing serious economic losses.LuxR transcriptional regulator is a key player in quorum sensing and plays important physiological and biochemical roles.In this paper,one of luxR homologous gene was amplified by PCR from E.amylovora.The mutant EaΔluxR was successfully constucted by homologous recombination,and the function studied preliminarily.The experimental results showed that,compared to the wild-type strain,the polyene macrolide biosynthesis,anti-oxidative stress,growth,and pathogenicity of mutant EaΔluxR declined.However,EaΔluxR still caused tobacco(Nicotiana tabacum) hypersensitive response,and there was no significant difference in antibiotic tolerance level and biofilm formation comparing to wild-type strain.These findings demonstrated that luxR gene in E.amylovora is involved in polyene macrolide biosynthesis,growth,and anti-oxidative stress and plays an important role in virulence.In addition,our results provid molecular evidence for in-depth understanding of the quorum sensing system of E.amylovora.