ISHS Acta Horticulturae 151: III International Workshop on Fire Blight
BIOCHEMICAL ASPECTS OF THE EPS OF ERWINIA AMYLOVORA II. THE EFFECT OF THE EPS ON OXIDATIVE ENZYMES AND BACTERIAL DEVELOPMENT IN LEAVES OF CYDONIA VULGARIS |
| Author: | W. Zeller |
| Abstract:
Based on the effect of the EPS in the reduction in respiration described previously, its effect on the activity of the enzymes in oxygen metabolism, such as peroxidase, phenoloxidase and  -glucosidase, was studied.
Crude EPS was collected as the ooze produced by inoculated slices from unripe pears, purified with DOWEX 50 and 1, and infiltrated under pressure into young leaves of Cydonia vulgaris.
As expected, the phenoloxidase exhibited a reduced rate of activity during the entire experimental period compared with the untreated control.
In comparison, the activity of peroxidase and -glucosidase exhibited an increase in their activity in the treated leaves, which was particularly evident towards the end of the experiment.
This increase in activity was probably associated with the disease symptoms, seen as small brown spots, which developed at this stage in the experiment.
In a further experiment, bacterial development in the initial stage of infection was inhibited in EPS-pretreated leaves compared with leaves only inoculated with bacteria. Thus, EPS appears to have a stabilizing effect on host cell structure in the initial development of the disease and to counteract an early tissue destruction like a hypersensitivity reaction. The full results of the above experiments will be published elsewhere. | |
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