Cloning And Function Analysis Of Crp And Tatc Gene From Erwinia Amylovora Strain Ncppb1665

Erwinia amylovora causes fire blight of pear, apple and many of the Rosaceae family. To control this disease, lots of researches have been focused on the mechanisms of the virulence in Erwinia amylovora.In this study, the homolog of crp gene, designated Eacrp, was identified and cloned in Erwinia amylovora for the first time. A crp disruption mutant EaAcrp was successfully generated by homologous recombination. Complement strain EaAcrp(pME-crp) was also constructed. Then crp gene was characterized to many phenotypes of the phytopathogens Erwinia amylovora. The results showed that, the crp mutant EaAcrp displayed the reduced virulence which observed in pear leaves and Kuerle fragrant pear. Furthermore, the mutants grew more slowly than the wild type strain NCPPB1665 in vitro, and EaAcrp impaired clearly in motility in soft agar medium. It was also obersved that the EaAcrp exhibited reductive production of extracellular polysaccharide (EPS). But EaAcrp was not affected the induction of hypersensitive response(HR) in nonhost tobacco,peroxide resistance,sedimentation,biofilm synthesis and AI-2 production compared to the wild type strain NCPPB1665.The homolog of tatC gene, designated Eatat, was identified and cloned too. A tatC disruption mutant EaAtat and the complement strain were constructed. Then tatC gene was characterized to virulence,HR,EPS production,motility and growth of Erwinia amylovora. Remarkably, tatC gene can influence the virulence,growth,EPS production and motility, but there were no differences in HR between the wild type and the mutants.