ISHS Acta Horticulturae 411: VII International Workshop on Fire Blight
FURTHER STUDIES ON PLANT EXTRACTS WITH A RESISTANCE INDUCTION EFFECT AGAINST ERWINIA AMYLOVORA |
| Authors: | J. Mosch, W. Zeller, M. Rieck, W. Ullrich |
| Abstract:
After testing of several plant extracts (PE) on their resistance induction effect against fire blight (Erwinia amylovora), two from mistletoe (Viscum album) and ivy (Hedera helix) showed the most remarkable effect. As criteria for induced resistance besides pathogenesis related parameters (bacterial development, symptom expression) in the host plant, different physiological changes were determined, which are involved in the resistance reaction of fire blight. Both plant extracts showed an inhibitory effect on the bacterial infection in the host plant. Considering the physiological parameters as in earlier studies, phenol metabolism was stimulated together with an induction of enzymatic activities of peroxidase (PO), polyphenoloxidase (PPO) and phenylalanine ammonia lyase (PAL). Moreover, changes in the content of PR-proteins (pathogenesis related proteins), as for instance  -1, 3 glucanase and chitinase, gave an indication for a resistance induction effect in the host plant after PE treatment.
The most effective extract of Hedera helix was tested under artificial infection conditions in the field, where 46.7% control could be observed compared with 38.1% of streptomycin treatment.
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