ISHS Acta Horticulturae 273: V International Workshop on Fireblight
VIRULENCE FACTORS OF ERWINIA AMYLOVORA |
| Authors: | K. Geider, H. Falkenstein, P. Bellemann, N. Jahn, T. Schwartz, R. Theiler, F. Bernhard |
| Abstract:
Mutations of the Erwinia amylovora genome affecting EPS-synthesis or growth properties of the bacterium often result in avirulence of the fireblight pathogen. Symptom development was attenuated by curing strains from a 29 kb plasmid, common to E. amylovora. Transposon mutagenesis of the recA gene results in UV-deficient slow-growing avirulent strains. A few strains produce dihydrophenylalanine, which is a toxin for plant cells. Its absence in many virulent strains points to a helper function rather than to a general virulence factor. Genomic DNA of E. amylovora has no homology to DNA fragments with cellulase and pectate lyase genes from Erwinia carotovora subsp. atroseptica. After expression of these genes in E. amylovora the enzymes are released by bacterial cell lysis. Pectate lyase supports prolonged propagation of E. amylovora on pear cells. | |
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