A GLOBAL REGULATORY GENE CONTROLS SECONDARY METABOLITES, MOTILITY, AND PATHOGENICITY FACTORS IN ERWINIA AMYLOVORA

We previously reported that a low copy plasmid carrying Erwinia carotovora rsmA suppressed the production of extracellular polysaccharide and protease, motility, the ability to cause hypersensitive reaction in tobacco leaves and the production of fire blight symptoms in apple shoots by E. amylovora strain E9. We document here that rsmA and flanking sequences have been conserved in E. amylovora strains.
Northern analysis using the rsmA DNA of E. carotovora as the probe also revealed that E. amylovora wild-type strains produced rsmA transcripts of ca. 310 bases.
By screening a library of E9 chromosomal DNA, we have isolated several plasmids that carry sequences homologous to the rsmA DNA of E. carotovora subsp. carotovora strain 71. One such plasmid suppresses the synthesis of the cell density (quorum) sensing signal, N-(3-oxohexanoyl)-L-homoserine lactone, production of extracellular enzymes, motility and pathogenicity of E. carotovora subsp. carotovora strains.
We conclude that (i) rsmA is present in E. amylovora; (ii) the gene is expressed in this bacterium under normal cultural conditions; and (iii) rsmA controls the production of various secondary metabolites as well as pathogenicity factors.

VII International Workshop on Fire Blight

A. Mukherjee, Y. Cui, Y. Liu, C. Korsi Dumenyo, A.K. Chatterjee

https://doi.org/10.17660/ActaHortic.1996.411.48